emacs/doc/misc/ada-mode.texi

\input texinfo  @c -*-texinfo-*-
@setfilename ../../info/ada-mode.info
@settitle Ada Mode
@include docstyle.texi

@copying
Copyright @copyright{} 1999--2017 Free Software Foundation, Inc.

@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with the Front-Cover Texts being ``A GNU Manual'',
and with the Back-Cover Texts as in (a) below.  A copy of the license
is included in the section entitled ``GNU Free Documentation License''.

(a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
modify this GNU manual.''
@end quotation
@end copying

@dircategory Emacs editing modes
@direntry
* Ada mode: (ada-mode).         Emacs mode for editing and compiling Ada code.
@end direntry

@titlepage
@sp 10
@title Ada Mode
@sp 2
@subtitle An Emacs major mode for programming in Ada
@subtitle Ada Mode Version 4.00
@sp 2
@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage

@contents

@node Top
@top Ada Mode

@ifnottex
@insertcopying
@end ifnottex

@menu
* Overview::
* Installation::                Installing Ada mode on your system
* Customization::               Setting up Ada mode to your taste
* Compiling Executing::         Working with your application within Emacs
* Project files::               Describing the organization of your project
* Compiling Examples::          A small tutorial
* Moving Through Ada Code::     Moving easily through Ada sources
* Identifier completion::       Finishing words automatically
* Automatic Smart Indentation::  Indenting your code automatically as you type
* Formatting Parameter Lists::  Formatting subprograms' parameter lists
                                     automatically
* Automatic Casing::            Adjusting the case of words automatically
* Statement Templates::         Inserting code templates
* Comment Handling::            Reformatting comments easily
* GNU Free Documentation License::  The license for this documentation.
* Index::
@end menu


@node Overview
@chapter Overview

The Emacs mode for programming in Ada helps the user in understanding
existing code and facilitates writing new code.

When the Gnu Ada compiler GNAT is used, the cross-reference
information output by the compiler is used to provide powerful code
navigation (jump to definition, find all uses, etc.).

When you open a file with a file extension of @file{.ads} or
@file{.adb}, Emacs will automatically load and activate Ada mode.

Ada mode works without any customization, if you are using the GNAT
compiler (@url{https://libre2.adacore.com/}) and the GNAT default
naming convention.

You must customize a few things if you are using a different compiler
or file naming convention; @xref{Other compiler}, @xref{Non-standard
file names}.

In addition, you may want to customize the indentation,
capitalization, and other things; @xref{Other customization}.

Finally, for large Ada projects, you will want to set up an Emacs
Ada mode project file for each project; @xref{Project files}. Note
that these are different from the GNAT project files used by gnatmake
and other GNAT commands.

See the Emacs info manual, section 'Running Debuggers Under Emacs',
for general information on debugging.

@node Installation
@chapter Installation

Ada mode is part of the standard Emacs distribution; if you use that,
no files need to be installed.

Ada mode is also available as a separate distribution, from the Emacs
Ada mode website
@uref{http://stephe-leake.org/emacs/ada-mode/emacs-ada-mode.html}. The
separate distribution may be more recent.

For installing the separate distribution, see the @file{README} file
in the distribution.

To see what version of Ada mode you have installed, do @kbd{M-x
ada-mode-version}.

The following files are provided with the Ada mode distribution:

@itemize @bullet

@item
@file{ada-mode.el}: The main file for Ada mode, providing indentation,
formatting of parameter lists, moving through code, comment handling
and automatic casing.

@item
@file{ada-prj.el}: GUI editing of Ada mode project files, using Emacs
widgets.

@item
@file{ada-stmt.el}: Ada statement templates.

@item
@file{ada-xref.el}: GNAT cross-references, completion of identifiers,
and compilation. Also provides project files (which are not
GNAT-specific).

@end itemize

@node Customization
@chapter Customizing Ada mode

Here we assume you are familiar with setting variables in Emacs,
either thru 'customize' or in elisp (in your @file{.emacs} file). For
a basic introduction to customize, elisp, and Emacs in general, see
the tutorial in
@iftex
@cite{The GNU Emacs Manual}.
@end iftex
@ifhtml
@cite{The GNU Emacs Manual}.
@end ifhtml
@ifinfo
@ref{Top, , The GNU Emacs Manual, emacs, The GNU Emacs Manual}.
@end ifinfo

These global Emacs settings are strongly recommended (put them in your
.emacs):

@example
(global-font-lock-mode t)
(transient-mark-mode t)
@end example

@samp{(global-font-lock-mode t)} turns on syntax
highlighting for all buffers (it is off by default because it may be
too slow for some machines).

@samp{(transient-mark-mode t)} highlights selected text.

See the Emacs help for each of these variables for more information.

@menu
* Non-standard file names::
* Other compiler::
* Other customization::
@end menu

@node Non-standard file names
@section Non-standard file names

By default, Ada mode is configured to use the GNAT file naming
convention, where file names are a simple modification of the Ada
names, and the extension for specs and bodies are
@samp{.ads} and @samp{.adb}, respectively.

Ada mode uses the file extensions to allow moving from a package body
to the corresponding spec and back.

Ada mode supports a list of alternative file extensions for specs and bodies.

For instance, if your spec and bodies files are called
@file{@var{unit}_s.ada} and @file{@var{unit}_b.ada}, respectively, you
can add the following to your @file{.emacs} file:

@example
(ada-add-extensions "_s.ada" "_b.ada")
@end example

You can define additional extensions:

@example
(ada-add-extensions ".ads" "_b.ada")
(ada-add-extensions ".ads" ".body")
@end example

This means that whenever Ada mode looks for the body for a file
whose extension is @file{.ads}, it will take the first available file
that ends with either @file{.adb}, @file{_b.ada} or
@file{.body}.

Similarly, if Ada mode is looking for a spec, it will look for
@file{.ads} or @file{_s.ada}.

If the filename is not derived from the Ada name following the GNAT
convention, things are a little more complicated. You then need to
rewrite the function @code{ada-make-filename-from-adaname}. Doing that
is beyond the scope of this manual; see the current definitions in
@file{ada-mode.el} and @file{ada-xref.el} for examples.

@node Other compiler
@section Other compiler

By default, Ada mode is configured to use the Gnu Ada compiler GNAT.

To use a different Ada compiler, you must specify the command lines
used to run that compiler, either in lisp variables or in Emacs
Ada mode project files. See @ref{Project file variables} for the list
of project variables, and the corresponding lisp variables.

@node Other customization
@section Other customization

All user-settable Ada mode variables can be set via the menu
@samp{Ada | Customize}.  Click on the @samp{Help} button there for help
on using customize.

To modify a specific variable, you can directly call the function
@code{customize-variable}; just type @kbd{M-x customize-variable
@key{RET} @var{variable-name} @key{RET}}).

Alternately, you can specify variable settings in the Emacs
configuration file, @file{.emacs}. This file is coded in Emacs lisp,
and the syntax to set a variable is the following:
@example
(setq variable-name value)
@end example

@node Compiling Executing
@chapter Compiling Executing

Ada projects can be compiled, linked, and executed using commands on
the Ada menu. All of these commands can be customized via a project
file (@pxref{Project files}), but the defaults are sufficient for using
the GNAT compiler for simple projects (single files, or several files
in a single directory).

Even when no project file is used, the GUI project editor (menu
@samp{Ada | Project | Edit}) shows the settings of the various project
file variables referenced here.

@menu
* Compile commands::
* Compiler errors::
@end menu

@node Compile commands
@section Compile commands

Here are the commands for building and using an Ada project, as
listed in the Ada menu.

In multi-file projects, there must be one file that is the main
program. That is given by the @code{main} project file variable;
it defaults to the current file if not yet set, but is also set by the
``set main and build'' command.

@table @code

@item Check file
Compiles the current file in syntax check mode, by running
@code{check_cmd} defined in the current project file. This typically
runs faster than full compile mode, speeding up finding and fixing
compilation errors.

This sets @code{main} only if it has not been set yet.

@item Compile file
Compiles the current file, by running @code{comp_cmd} from the current
project file.

This does not set @code{main}.

@item Set main and Build
Sets @code{main} to the current file, then executes the Build
command.

@item Show main
Display @code{main} in the message buffer.

@item Build
Compiles all obsolete units of the current @code{main}, and links
@code{main}, by running @code{make_cmd} from the current project.

This sets @code{main} only if it has not been set yet.

@item Run
Executes the main program in a shell, displayed in a separate Emacs
buffer. This runs @code{run_cmd} from the current project. The
execution buffer allows for interactive input/output.

To modify the run command, in particular to provide or change the
command line arguments, type @kbd{C-u} before invoking the command.

This command is not available for a cross-compilation toolchain.

@end table
It is important when using these commands to understand how
@code{main} is used and changed.

Build runs 'gnatmake' on the main unit. During a typical edit/compile
session, this is the only command you need to invoke, which is why it
is bound to @kbd{C-c C-c}. It will compile all files needed by the
main unit, and display compilation errors in any of them.

Note that Build can be invoked from any Ada buffer; typically you will
be fixing errors in files other than the main, but you don't have to
switch back to the main to invoke the compiler again.

Novices and students typically work on single-file Ada projects. In
this case, @kbd{C-c C-m} will normally be the only command needed; it
will build the current file, rather than the last-built main.

There are three ways to change @code{main}:

@enumerate
@item
Invoke @samp{Ada | Set main and Build}, which sets @code{main} to
the current file.

@item
Invoke @samp{Ada | Project | Edit}, edit @code{main} and
@code{main}, and click @samp{[save]}

@item
Invoke @samp{Ada | Project | Load}, and load a project file that specifies @code{main}

@end enumerate

@node Compiler errors
@section Compiler errors

The @code{Check file}, @code{Compile file}, and @code{Build} commands
all place compilation errors in a separate buffer named
@file{*compilation*}.

Each line in this buffer will become active: you can simply click on
it with the middle button of the mouse, or move point to it and press
@key{RET}. Emacs will then display the relevant source file and put
point on the line and column where the error was found.

You can also press the @kbd{C-x `} key (@code{next-error}), and Emacs
will jump to the first error. If you press that key again, it will
move you to the second error, and so on.

Some error messages might also include references to other files. These
references are also clickable in the same way, or put point after the
line number and press @key{RET}.

@node Project files
@chapter Project files

An Emacs Ada mode project file specifies what directories hold sources
for your project, and allows you to customize the compilation commands
and other things on a per-project basis.

Note that Ada mode project files @file{*.adp} are different than GNAT
compiler project files @file{*.gpr}. However, Emacs Ada mode can use a
GNAT project file to specify the project directories. If no
other customization is needed, a GNAT project file can be used without
an Emacs Ada mode project file.

@menu
* Project File Overview::
* GUI Editor::
* Project file variables::
@end menu

@node Project File Overview
@section Project File Overview

Project files have a simple syntax; they may be edited directly. Each
line specifies a project variable name and its value, separated by ``='':
@example
src_dir=/Projects/my_project/src_1
src_dir=/Projects/my_project/src_2
@end example

Some variables (like @code{src_dir}) are lists; multiple occurrences
are concatenated.

There must be no space between the variable name and ``='', and no
trailing spaces.

Alternately, a GUI editor for project files is available (@pxref{GUI
Editor}). It uses Emacs widgets, similar to Emacs customize.

The GUI editor also provides a convenient way to view current project
settings, if they have been modified using menu commands rather than
by editing the project file.

After the first Ada mode build command is invoked, there is always a
current project file, given by the lisp variable
@code{ada-prj-default-project-file}. Currently, the only way to show
the current project file is to invoke the GUI editor.

To find the project file the first time, Ada mode uses the following
search algorithm:

@itemize @bullet
@item
If @code{ada-prj-default-project-file} is set, use that.

@item
Otherwise, search for a file in the current directory with
the same base name as the Ada file, but extension given by
@code{ada-prj-file-extension} (default @code{".adp"}).

@item
If not found, search for @file{*.adp} in the current directory; if
several are found, prompt the user to select one.

@item
If none are found, use @file{default.adp} in the current directory (even
if it does not exist).

@end itemize

This algorithm always sets @code{ada-prj-default-project-file}, even
when the file does not actually exist.

To change the project file before or after the first one is found,
invoke @samp{Ada | Project | Load ...}.

Or, in lisp, evaluate @code{(ada-set-default-project-file "/path/file.adp")}.
This sets @code{ada-prj-default-project-file}, and reads the project file.

You can also specify a GNAT project file to @samp{Ada | Project | Load
...} or @code{ada-set-default-project-file}. Emacs Ada mode checks the
file extension; if it is @code{.gpr}, the file is treated as a GNAT
project file. Any other extension is treated as an Emacs Ada mode
project file.

@node GUI Editor
@section GUI Editor

The project file editor is invoked with the menu @samp{Ada | Projects
| Edit}.

Once in the buffer for editing the project file, you can save your
modification using the @samp{[save]} button at the bottom of the
buffer, or the @kbd{C-x C-s} binding. To cancel your modifications,
kill the buffer or click on the @samp{[cancel]} button.

@node Project file variables
@section Project file variables

The following variables can be defined in a project file; some can
also be defined in lisp variables.

To set a project variable that is a list, specify each element of the
list on a separate line in the project file.

Any project variable can be referenced in other project variables,
using a shell-like notation. For instance, if the variable
@code{comp_cmd} contains @code{$@{comp_opt@}}, the value of the
@code{comp_opt} variable will be substituted when @code{comp_cmd} is
used.

In addition, process environment variables can be referenced using the
same syntax, or the normal @code{$var} syntax.

Most project variables have defaults that can be changed by setting
lisp variables; the table below identifies the lisp variable for each
project variable. Lisp variables corresponding to project variables
that are lists are lisp lists.

In general, project variables are evaluated when referenced in
Emacs Ada mode commands. Relative file paths are expanded to
absolute relative to @code{$@{build_dir@}}.

Here is the list of variables. In the default values, the current
directory @code{"."} is the project file directory.

@table @asis
@c defined in ada-default-prj-properties; alphabetical order

@item @code{ada_project_path_sep}   [default: @code{":" or ";"}]
Path separator for @code{ADA_PROJECT_PATH}. It defaults to the correct
value for a native implementation of GNAT for the current operating
system. The user must override this when using Windows native GNAT
with Cygwin Emacs, and perhaps in other cases.

Lisp variable: @code{ada-prj-ada-project-path-sep}.

@item @code{ada_project_path}   [default: @code{""}]
A list of directories to search for GNAT project files.

If set, the @code{ADA_PROJECT_PATH} process environment variable is
set to this value in the Emacs process when the Emacs Ada mode project
is selected via menu @samp{Ada | Project | Load}.

For @code{ada_project_path}, relative file paths are expanded to
absolute when the Emacs Ada project file is read, rather than when the
project file is selected.

For example if the project file is in the directory
@file{/home/myproject}, the environment variable @code{GDS_ROOT} is
set to @code{/home/shared}, and the project file contains:
@example
ada_project_path_sep=:
ada_project_path=$GDS_ROOT/makerules
ada_project_path=../opentoken
@end example
then as a result the environment variable @code{ADA_PROJECT_PATH} will
be set to @code{"/home/shared/makerules:/home/opentoken/"}.

The default value is not the current value of this environment
variable, because that will typically have been set by another
project, and will therefore be incorrect for this project.

If you have the environment variable set correctly for all of your
projects, you do not need to set this project variable.

@item @code{bind_opt}       [default: @code{""}]
Holds user binder options; used in the default build commands.

Lisp variable: @code{ada-prj-default-bind-opt}.

@item @code{build_dir}      [default: @code{"."}]
The compile commands will be issued in this directory.

@item @code{casing}         [default: @code{("~/.emacs_case_exceptions")}]
List of files containing casing exceptions. See the help on
@code{ada-case-exception-file} for more info.
@c FIXME: section on case exceptions

Lisp variable: @code{ada-case-exception-file}.

@item @code{check_cmd}      [default: @code{"$@{cross_prefix@}gnatmake -u -c -gnatc $@{gnatmake_opt@} $@{full_current@} -cargs $@{comp_opt@}"}]
Command used to syntax check a single file.
The name of the file is substituted for @code{full_current}.

Lisp variable: @code{ada-prj-default-check-cmd}

@item @code{comp_cmd}       [default: @code{"$@{cross_prefix@}gnatmake -u -c $@{gnatmake_opt@} $@{full_current@} -cargs $@{comp_opt@}"}]
Command used to compile a single file.
The name of the file is substituted for @code{full_current}.

Lisp variable: @code{ada-prj-default-comp-cmd}.

@item @code{comp_opt}       [default: @code{"-gnatq -gnatQ"}]
Holds user compiler options; used in the default compile commands. The
default value tells gnatmake to generate library files for
cross-referencing even when there are errors.

If source code for the project is in multiple directories, the
appropriate compiler options must be added here. @ref{Set source
search path} for examples of this. Alternately, GNAT project files may
be used; @ref{Use GNAT project file}.

Lisp variable: @code{ada-prj-default-comp-opt}.

@item @code{cross_prefix}   [default: @code{""}]
Name of target machine in a cross-compilation environment. Used in
default compile and build commands.

@item @code{debug_cmd}      [default: @code{"$@{cross_prefix@}gdb $@{main@}"}]
Command used to debug the application

Lisp variable: @code{ada-prj-default-debugger}.

@item @code{debug_post_cmd} [default: @code{""}]
Command executed after @code{debug_cmd}.

@item @code{debug_pre_cmd}  [default: @code{"cd $@{build_dir@}"}]
Command executed before @code{debug_cmd}.

@item @code{gnatfind_opt}   [default: @code{"-rf"}]
Holds user gnatfind options; used in the default find commands.

Lisp variable: @code{ada-prj-gnatfind-switches}.

@item @code{gnatmake_opt}   [default: @code{"-g"}]
Holds user gnatmake options; used in the default build commands.

Lisp variable: @code{ada-prj-default-gnatmake-opt}.

@item @code{gpr_file}   [default: @code{""}]
Specify GNAT project file.

If set, the source and object directories specified in the GNAT
project file are appended to @code{src_dir} and @code{obj_dir}. This
allows specifying Ada source directories with a GNAT project file, and
other source directories with the Emacs project file.

In addition, @code{-P@{gpr_file@}} is added to the project variable
@code{gnatmake_opt} whenever it is referenced. With the default
project variables, this passes the project file to all gnatmake
commands.

Lisp variable: @code{ada-prj-default-gpr-file}.

@c FIXME: add gnatstub-opts

@item @code{link_opt}       [default: @code{""}]
Holds user linker options; used in the default build commands.

Lisp variable: @code{ada-prj-default-link-opt}.

@item @code{main}           [default: current file]
Specifies the name of the executable file for the project; used in the
default build commands.

@item @code{make_cmd}       [default: @code{"$@{cross_prefix@}gnatmake -o $@{main@} $@{main@} $@{gnatmake_opt@} -cargs $@{comp_opt@} -bargs $@{bind_opt@} -largs $@{link_opt@}"}]
Command used to build the application.

Lisp variable: @code{ada-prj-default-make-cmd}.

@item @code{obj_dir}        [default: @code{"."}]
A list of directories to search for library files. Ada mode searches
this list for the @samp{.ali} files generated by GNAT that contain
cross-reference information.

The compiler commands must place the @samp{.ali} files in one of these
directories; the default commands do that.

@item @code{remote_machine} [default: @code{""}]
Name of the machine to log into before issuing the compile and build
commands. If this variable is empty, the command will be run on the
local machine.

@item @code{run_cmd}        [default: @code{"./$@{main@}"}]
Command used to run the application.

@item @code{src_dir}        [default: @code{"."}]
A list of directories to search for source files, both for compile
commands and source navigation.

@end table

@node Compiling Examples
@chapter Compiling Examples

We present several small projects, and walk thru the process of
compiling, linking, and running them.

The first example illustrates more Ada mode features than the others;
you should work thru that example before doing the others.

All of these examples assume you are using GNAT.

The source for these examples is available on the Emacs Ada mode
website mentioned in @xref{Installation}.

@menu
* No project files::            Just menus
* Set compiler options::        A basic Ada mode project file
* Set source search path::      Source in multiple directories
* Use GNAT project file::
* Use multiple GNAT project files::
@end menu

@node No project files
@section No project files
This example uses no project files.

First, create a directory @file{Example_1}, containing:

@file{hello.adb}:

@example
with Ada.Text_IO;
procedure Hello
is begin
   Put_Line("Hello from hello.adb");
end Hello;
@end example

Yes, this is missing ``use Ada.Text_IO;'' - we want to demonstrate
compiler error handling.

@file{hello_2.adb}:

@example
with Hello_Pkg;
procedure Hello_2
is begin
   Hello_Pkg.Say_Hello;
end Hello_2;
@end example

This file has no errors.

@file{hello_pkg.ads}:

@example
package Hello_Pkg is
   procedure Say_Hello;
end Hello_Pkg;
@end example

This file has no errors.

@file{hello_pkg.adb}:

@example
with Ada.Text_IO;
package Hello_Pkg is
   procedure Say_Hello
   is begin
      Ada.Text_IO.Put_Line ("Hello from hello_pkg.adb");
   end Say_Hello;
end Hello_Pkg;
@end example

Yes, this is missing the keyword @code{body}; another compiler error
example.

In buffer @file{hello.adb}, invoke @samp{Ada | Check file}. You should
get a @file{*compilation*} buffer containing something like (the
directory paths will be different):

@smallexample
cd c:/Examples/Example_1/
gnatmake -u -c -gnatc -g c:/Examples/Example_1/hello.adb -cargs -gnatq -gnatQ
gcc -c -Ic:/Examples/Example_1/ -gnatc -g -gnatq -gnatQ -I- c:/Examples/Example_1/hello.adb
hello.adb:4:04: "Put_Line" is not visible
hello.adb:4:04: non-visible declaration at a-textio.ads:264
hello.adb:4:04: non-visible declaration at a-textio.ads:260
gnatmake: "c:/Examples/Example_1/hello.adb" compilation error
@end smallexample

If you have enabled font-lock, the lines with actual errors (starting
with @file{hello.adb}) are highlighted, with the file name in red.

Now type @kbd{C-x `} (on a PC keyboard, @key{`} is next to @key{1}).
Or you can click the middle mouse button on the first error line. The
compilation buffer scrolls to put the first error on the top line, and
point is put at the place of the error in the @file{hello.adb} buffer.

To fix the error, change the line to be

@example
    Ada.Text_IO.Put_Line ("hello from hello.adb");
@end example

Now invoke @samp{Ada | Show main}; this displays @samp{Ada mode main: hello}.

Now (in buffer @file{hello.adb}), invoke @samp{Ada | Build}. You are
prompted to save the file (if you haven't already). Then the
compilation buffer is displayed again, containing:

@example
cd c:/Examples/Example_1/
gnatmake -o hello hello -g -cargs -gnatq -gnatQ -bargs  -largs
gcc -c -g -gnatq -gnatQ hello.adb
gnatbind -x hello.ali
gnatlink hello.ali -o hello.exe -g
@end example

The compilation has succeeded without errors; @file{hello.exe} now
exists in the same directory as @file{hello.adb}.

Now invoke @samp{Ada | Run}. A @file{*run*} buffer is displayed,
containing

@example
Hello from hello.adb

Process run finished
@end example

That completes the first part of this example.

Now we will compile a multi-file project. Open the file
@file{hello_2.adb}, and invoke @samp{Ada | Set main and Build}. This
finds an error in @file{hello_pkg.adb}:

@example
cd c:/Examples/Example_1/
gnatmake -o hello_2 hello_2 -g -cargs -gnatq -gnatQ -bargs  -largs
gcc -c -g -gnatq -gnatQ hello_pkg.adb
hello_pkg.adb:2:08: keyword "body" expected here [see file name]
gnatmake: "hello_pkg.adb" compilation error
@end example

This demonstrates that gnatmake finds the files needed by the main
program. However, it cannot find files in a different directory,
unless you use an Emacs Ada mode project file to specify the other directories;
@xref{Set source search path}, or a GNAT project file; @ref{Use GNAT
project file}.

Invoke @samp{Ada | Show main}; this displays @file{Ada mode main: hello_2}.

Move to the error with @kbd{C-x `}, and fix the error by adding @code{body}:

@example
package body Hello_Pkg is
@end example

Now, while still in @file{hello_pkg.adb}, invoke @samp{Ada | Build}.
gnatmake successfully builds @file{hello_2}. This demonstrates that
Emacs has remembered the main file, in the project variable
@code{main}, and used it for the Build command.

Finally, again while in @file{hello_pkg.adb}, invoke @samp{Ada | Run}.
The @file{*run*} buffer displays @code{Hello from hello_pkg.adb}.

One final point. If you switch back to buffer @file{hello.adb}, and
invoke @samp{Ada | Run}, @file{hello_2.exe} will be run. That is
because @code{main} is still set to @code{hello_2}, as you can
see when you invoke @samp{Ada | Project | Edit}.

There are three ways to change @code{main}:

@enumerate
@item
Invoke @samp{Ada | Set main and Build}, which sets @code{main} to
the current file.

@item
Invoke @samp{Ada | Project | Edit}, edit @code{main}, and click @samp{[save]}

@item
Invoke @samp{Ada | Project | Load}, and load a project file that specifies @code{main}

@end enumerate

@node Set compiler options
@section Set compiler options

This example illustrates using an Emacs Ada mode project file to set a
compiler option.

If you have files from @file{Example_1} open in Emacs, you should
close them so you don't get confused. Use menu @samp{File | Close
(current buffer)}.

In directory @file{Example_2}, create these files:

@file{hello.adb}:

@example
with Ada.Text_IO;
procedure Hello
is begin
   Put_Line("Hello from hello.adb");
end Hello;
@end example

This is the same as @file{hello.adb} from @file{Example_1}. It has two
errors; missing ``use Ada.Text_IO;'', and no space between
@code{Put_Line} and its argument list.

@file{hello.adp}:

@example
comp_opt=-gnatyt
@end example

This tells the GNAT compiler to check for token spacing; in
particular, there must be a space preceding a parenthesis.

In buffer @file{hello.adb}, invoke @samp{Ada | Project | Load...}, and
select @file{Example_2/hello.adp}.

Then, again in buffer @file{hello.adb}, invoke @samp{Ada | Set main and
Build}. You should get a @file{*compilation*} buffer containing
something like (the directory paths will be different):

@example
cd c:/Examples/Example_2/
gnatmake -o hello hello -g -cargs -gnatyt  -bargs  -largs
gcc -c -g -gnatyt hello.adb
hello.adb:4:04: "Put_Line" is not visible
hello.adb:4:04: non-visible declaration at a-textio.ads:264
hello.adb:4:04: non-visible declaration at a-textio.ads:260
hello.adb:4:12: (style) space required
gnatmake: "hello.adb" compilation error
@end example

Compare this to the compiler output in @ref{No project files}; the
gnatmake option @code{-cargs -gnatq -gnatQ} has been replaced by
@code{-cargs -gnaty}, and an additional error is reported in
@file{hello.adb} on line 4. This shows that @file{hello.adp} is being
used to set the compiler options.

Fixing the error, linking and running the code proceed as in @ref{No
project files}.

@node Set source search path
@section Set source search path

In this example, we show how to deal with files in more than one
directory. We start with the same code as in @ref{No project files};
create those files (with the errors present)

Create the directory @file{Example_3}, containing:

@file{hello_pkg.ads}:

@example
package Hello_Pkg is
   procedure Say_Hello;
end Hello_Pkg;
@end example

@file{hello_pkg.adb}:

@example
with Ada.Text_IO;
package Hello_Pkg is
   procedure Say_Hello
   is begin
      Ada.Text_IO.Put_Line ("Hello from hello_pkg.adb");
   end Say_Hello;
end Hello_Pkg;
@end example

These are the same files from example 1; @file{hello_pkg.adb} has an
error on line 2.

In addition, create a directory @file{Example_3/Other}, containing these files:

@file{Other/hello_3.adb}:

@example
with Hello_Pkg;
with Ada.Text_IO; use Ada.Text_IO;
procedure Hello_3
is begin
   Hello_Pkg.Say_Hello;
   Put_Line ("From hello_3");
end Hello_3;
@end example

There are no errors in this file.

@file{Other/other.adp}:

@example
src_dir=..
comp_opt=-I..
@end example

Note that there must be no trailing spaces.

In buffer @file{hello_3.adb}, invoke @samp{Ada | Project | Load...}, and
select @file{Example_3/Other/other.adp}.

Then, again in @file{hello_3.adb}, invoke @samp{Ada | Set main and
Build}. You should get a @file{*compilation*} buffer containing
something like (the directory paths will be different):

@example
cd c:/Examples/Example_3/Other/
gnatmake -o hello_3 hello_3 -g -cargs -I.. -bargs  -largs
gcc -c -g -I.. hello_3.adb
gcc -c -I./ -g -I.. -I- C:\Examples\Example_3\hello_pkg.adb
hello_pkg.adb:2:08: keyword "body" expected here [see file name]
gnatmake: "C:\Examples\Example_3\hello_pkg.adb" compilation error
@end example

Compare the @code{-cargs} option to the compiler output in @ref{Set
compiler options}; this shows that @file{other.adp} is being used to
set the compiler options.

Move to the error with @kbd{C-x `}. Ada mode searches the list of
directories given by @code{src_dir} for the file mentioned in the
compiler error message.

Fixing the error, linking and running the code proceed as in @ref{No
project files}.

@node Use GNAT project file
@section Use GNAT project file

In this example, we show how to use a GNAT project file, with no Ada
mode project file.

Create the directory @file{Example_4}, containing:

@file{hello_pkg.ads}:

@example
package Hello_Pkg is
   procedure Say_Hello;
end Hello_Pkg;
@end example

@file{hello_pkg.adb}:

@example
with Ada.Text_IO;
package Hello_Pkg is
   procedure Say_Hello
   is begin
      Ada.Text_IO.Put_Line ("Hello from hello_pkg.adb");
   end Say_Hello;
end Hello_Pkg;
@end example

These are the same files from example 1; @file{hello_pkg.adb} has an
error on line 2.

In addition, create a directory @file{Example_4/Gnat_Project},
containing these files:

@file{Gnat_Project/hello_4.adb}:

@example
with Hello_Pkg;
with Ada.Text_IO; use Ada.Text_IO;
procedure Hello_4
is begin
   Hello_Pkg.Say_Hello;
   Put_Line ("From hello_4");
end Hello_4;
@end example

There are no errors in this file.

@file{Gnat_Project/hello_4.gpr}:

@example
Project Hello_4 is
   for Source_Dirs use (".", "..");
end Hello_4;
@end example

In buffer @file{hello_4.adb}, invoke @samp{Ada | Project | Load...}, and
select @file{Example_4/Gnat_Project/hello_4.gpr}.

Then, again in @file{hello_4.adb}, invoke @samp{Ada | Set main and
Build}. You should get a @file{*compilation*} buffer containing
something like (the directory paths will be different):

@smallexample
cd c:/Examples/Example_4/Gnat_Project/
gnatmake -o hello_4 hello_4 -Phello_4.gpr -cargs -gnatq -gnatQ -bargs  -largs
gcc -c -g -gnatyt -gnatq -gnatQ -I- -gnatA c:\Examples\Example_4\Gnat_Project\hello_4.adb
gcc -c -g -gnatyt -gnatq -gnatQ -I- -gnatA c:\Examples\Example_4\hello_pkg.adb
hello_pkg.adb:2:08: keyword "body" expected here [see file name]
gnatmake: "c:\examples\example_4\hello_pkg.adb" compilation error
@end smallexample

Compare the @code{gcc} options to the compiler output in @ref{Set
compiler options}; this shows that @file{hello_4.gpr} is being used to
set the compiler options.

Fixing the error, linking and running the code proceed as in @ref{No
project files}.

@node Use multiple GNAT project files
@section Use multiple GNAT project files

In this example, we show how to use multiple GNAT project files,
specifying the GNAT project search path in an Ada mode project file.

Create the directory @file{Example_4} as specified in @ref{Use GNAT
project file}.

Create the directory @file{Example_5}, containing:

@file{hello_5.adb}:

@example
with Hello_Pkg;
with Ada.Text_IO; use Ada.Text_IO;
procedure Hello_5
is begin
   Hello_Pkg.Say_Hello;
   Put_Line ("From hello_5");
end Hello_5;
@end example

There are no errors in this file.

@file{hello_5.adp}:

@example
ada_project_path=../Example_4/Gnat_Project
gpr_file=hello_5.gpr
@end example

@file{hello_5.gpr}:

@example
with "hello_4";
Project Hello_5 is
   for Source_Dirs use (".");
   package Compiler is
      for Default_Switches ("Ada") use ("-g", "-gnatyt");
   end Compiler;
end Hello_5;
@end example

In buffer @file{hello_5.adb}, invoke @samp{Ada | Project | Load...}, and
select @file{Example_5/hello_5.adp}.

Then, again in @file{hello_5.adb}, invoke @samp{Ada | Set main and
Build}. You should get a @file{*compilation*} buffer containing
something like (the directory paths will be different):

@smallexample
cd c:/Examples/Example_5/
gnatmake -o hello_5 hello_5 -Phello_5.gpr -g -cargs -gnatq -gnatQ -bargs  -largs
gcc -c -g -gnatyt -g -gnatq -gnatQ -I- -gnatA c:\Examples\Example_5\hello_5.adb
gcc -c -g -gnatyt -g -gnatq -gnatQ -I- -gnatA c:\Examples\Example_4\hello_pkg.adb
hello_pkg.adb:2:08: keyword "body" expected here [see file name]
gnatmake: "c:\examples\example_4\hello_pkg.adb" compilation error
@end smallexample

Now type @kbd{C-x `}. @file{Example_4/hello_pkg.adb} is shown,
demonstrating that @file{hello_5.gpr} and @file{hello_4.gpr} are being
used to set the compilation search path.

@node Moving Through Ada Code
@chapter Moving Through Ada Code

There are several easy to use commands to navigate through Ada code. All
these functions are available through the Ada menu, and you can also
use the following key bindings or the command names. Some of these
menu entries are available only if the GNAT compiler is used, since
the implementation relies on the GNAT cross-referencing information.

@table @kbd
@item M-C-e
@findex ada-next-procedure
Move to the next function/procedure/task, which ever comes next
(@code{ada-next-procedure}).
@item M-C-a
@findex ada-previous-procedure
Move to previous function/procedure/task
(@code{ada-previous-procedure}).
@item M-x ada-next-package
@findex ada-next-package
Move to next package.
@item M-x ada-previous-package
@findex ada-previous-package
Move to previous package.
@item C-c C-a
@findex ada-move-to-start
Move to matching start of @code{end} (@code{ada-move-to-start}).  If
point is at the end of a subprogram, this command jumps to the
corresponding @code{begin} if the user option
@code{ada-move-to-declaration} is @code{nil} (default), otherwise it jumps to
the subprogram declaration.
@item C-c C-e
@findex ada-move-to-end
Move point to end of current block (@code{ada-move-to-end}).
@item C-c o
Switch between corresponding spec and body file
(@code{ff-find-other-file}).  If point is in a subprogram, position
point on the corresponding declaration or body in the other file.
@item C-c c-d
@findex ada-goto-declaration
Move from any reference to its declaration, for from a declaration to
its body (for procedures, tasks, private and incomplete types).
@item C-c C-r
@findex ada-find-references
Runs the @file{gnatfind} command to search for all references to the
identifier surrounding point (@code{ada-find-references}). Use
@kbd{C-x `} (@code{next-error}) to visit each reference (as for
compilation errors).
@end table

If the @code{ada-xref-create-ali} variable is non-@code{nil}, Emacs
will try to run GNAT for you whenever cross-reference information is
needed, and is older than the current source file.

@node Identifier completion
@chapter Identifier completion

Emacs and Ada mode provide two general ways for the completion of
identifiers. This is an easy way to type faster: you just have to type
the first few letters of an identifiers, and then loop through all the
possible completions.

The first method is general for Emacs. It works by parsing all open
files for possible completions.

For instance, if the words @samp{my_identifier}, @samp{my_subprogram}
are the only words starting with @samp{my} in any of the opened files,
then you will have this scenario:

@example
You type:  my@kbd{M-/}
Emacs inserts:  @samp{my_identifier}
If you press @kbd{M-/} once again, Emacs replaces @samp{my_identifier} with
@samp{my_subprogram}.
Pressing @kbd{M-/} once more will bring you back to @samp{my_identifier}.
@end example

This is a very fast way to do completion, and the casing of words will
also be respected.

The second method (@kbd{C-@key{TAB}}) is specific to Ada mode and the GNAT
compiler. Emacs will search the cross-information for possible
completions.

The main advantage is that this completion is more accurate: only
existing identifier will be suggested.

On the other hand, this completion is a little bit slower and requires
that you have compiled your file at least once since you created that
identifier.

@table @kbd
@item C-@key{TAB}
@findex ada-complete-identifier
Complete current identifier using cross-reference information.
@item M-/
Complete identifier using buffer information (not Ada-specific).
@end table

@node Automatic Smart Indentation
@chapter Automatic Smart Indentation

Ada mode comes with a full set of rules for automatic indentation. You
can also configure the indentation, via the following variables:

@table @asis
@item @code{ada-broken-indent}           (default value: 2)
Number of columns to indent the continuation of a broken line.

@item @code{ada-indent}                  (default value: 3)
Number of columns for default indentation.

@item @code{ada-indent-record-rel-type}  (default value: 3)
Indentation for @code{record} relative to @code{type} or @code{use}.

@item @code{ada-indent-return}           (default value: 0)
Indentation for @code{return} relative to @code{function} (if
@code{ada-indent-return} is greater than 0), or the open parenthesis
(if @code{ada-indent-return} is negative or 0).  Note that in the second
case, when there is no open parenthesis, the indentation is done
relative to @code{function} with the value of @code{ada-broken-indent}.

@item @code{ada-label-indent}            (default value: -4)
Number of columns to indent a label.

@item @code{ada-stmt-end-indent}         (default value: 0)
Number of columns to indent a statement @code{end} keyword on a separate line.

@item @code{ada-when-indent}             (default value: 3)
Indentation for @code{when} relative to @code{exception} or @code{case}.

@item @code{ada-indent-is-separate}      (default value: t)
Non-@code{nil} means indent @code{is separate} or @code{is abstract} if on a single line.

@item @code{ada-indent-to-open-paren}    (default value: t)
Non-@code{nil} means indent according to the innermost open parenthesis.

@item @code{ada-indent-after-return}     (default value: t)
Non-@code{nil} means that the current line will also be re-indented
before inserting a newline, when you press @key{RET}.
@end table

Most of the time, the indentation will be automatic, i.e., when you
press @key{RET}, the cursor will move to the correct column on the
next line.

You can also indent single lines, or the current region, with @key{TAB}.

Another mode of indentation exists that helps you to set up your
indentation scheme. If you press @kbd{C-c @key{TAB}}, Ada mode will do
the following:

@itemize @bullet
@item
Reindent the current line, as @key{TAB} would do.
@item
Temporarily move the cursor to a reference line, i.e., the line that
was used to calculate the current indentation.
@item
Display in the message window the name of the variable that provided
the offset for the indentation.
@end itemize

The exact indentation of the current line is the same as the one for the
reference line, plus an offset given by the variable.

@table @kbd
@item @key{TAB}
Indent the current line or the current region.
@item C-M-\
Indent lines in the current region.
@item C-c @key{TAB}
Indent the current line and display the name of the variable used for
indentation.
@end table

@node Formatting Parameter Lists
@chapter Formatting Parameter Lists

@table @kbd
@item C-c C-f
@findex ada-format-paramlist
Format the parameter list (@code{ada-format-paramlist}).
@end table

This aligns the declarations on the colon (@samp{:}) separating
argument names and argument types, and aligns the @code{in},
@code{out} and @code{in out} keywords.

@node Automatic Casing
@chapter Automatic Casing

Casing of identifiers, attributes and keywords is automatically
performed while typing when the variable @code{ada-auto-case} is set.
Every time you press a word separator, the previous word is
automatically cased.

You can customize the automatic casing differently for keywords,
attributes and identifiers. The relevant variables are the following:
@code{ada-case-keyword}, @code{ada-case-attribute} and
@code{ada-case-identifier}.

All these variables can have one of the following values:

@table @code
@item downcase-word
The word will be lowercase. For instance @code{My_vARIable} is
converted to @code{my_variable}.

@item upcase-word
The word will be uppercase. For instance @code{My_vARIable} is
converted to @code{MY_VARIABLE}.

@item ada-capitalize-word
The first letter and each letter following an underscore (@samp{_})
are uppercase, others are lowercase. For instance @code{My_vARIable}
is converted to @code{My_Variable}.

@item ada-loose-case-word
Characters after an underscore @samp{_} character are uppercase,
others are not modified. For instance @code{My_vARIable} is converted
to @code{My_VARIable}.
@end table

Ada mode allows you to define exceptions to these rules, in a file
specified by the variable @code{ada-case-exception-file}
(default @file{~/.emacs_case_exceptions}). Each line in this file
specifies the casing of one word or word fragment. Comments may be
included, separated from the word by a space.

If the word starts with an asterisk (@key{*}), it defines the casing
as a word fragment (or ``substring''); part of a word between two
underscores or word boundary.

For example:

@example
DOD        Department of Defense
*IO
GNAT       The GNAT compiler from Ada Core Technologies
@end example

The word fragment @code{*IO} applies to any word containing ``_io'';
@code{Text_IO}, @code{Hardware_IO}, etc.

@findex ada-create-case-exception
There are two ways to add new items to this file: you can simply edit
it as you would edit any text file. Or you can position point on the
word you want to add, and select menu @samp{Ada | Edit | Create Case
Exception}, or press @kbd{C-c C-y} (@code{ada-create-case-exception}).
The word will automatically be added to the current list of exceptions
and to the file.

To define a word fragment case exception, select the word fragment,
then select menu @samp{Ada | Edit | Create Case Exception Substring}.

It is sometimes useful to have multiple exception files around (for
instance, one could be the standard Ada acronyms, the second some
company specific exceptions, and the last one some project specific
exceptions). If you set up the variable @code{ada-case-exception-file}
as a list of files, each of them will be parsed and used in your emacs
session. However, when you save a new exception through the menu, as
described above, the new exception will be added to the first file in
the list.

@table @kbd
@item C-c C-b
@findex ada-adjust-case-buffer
Adjust case in the whole buffer (@code{ada-adjust-case-buffer}).
@item C-c C-y
Create a new entry in the exception dictionary, with the word under
the cursor (@code{ada-create-case-exception})
@item C-c C-t
@findex ada-case-read-exceptions
Rereads the exception dictionary from the file
@code{ada-case-exception-file} (@code{ada-case-read-exceptions}).
@end table

@node Statement Templates
@chapter Statement Templates

Templates are defined for most Ada statements, using the Emacs
``skeleton'' package. They can be inserted in the buffer using the
following commands:

@table @kbd
@item C-c t b
@findex ada-exception-block
exception Block (@code{ada-exception-block}).
@item C-c t c
@findex ada-case
case (@code{ada-case}).
@item C-c t d
@findex ada-declare-block
declare Block (@code{ada-declare-block}).
@item C-c t e
@findex ada-else
else (@code{ada-else}).
@item C-c t f
@findex ada-for-loop
for Loop (@code{ada-for-loop}).
@item C-c t h
@findex ada-header
Header (@code{ada-header}).
@item C-c t i
@findex ada-if
if (@code{ada-if}).
@item C-c t k
@findex ada-package-body
package Body (@code{ada-package-body}).
@item C-c t l
@findex ada-loop
loop (@code{ada-loop}).
@item C-c p
@findex ada-subprogram-body
subprogram body (@code{ada-subprogram-body}).
@item C-c t t
@findex ada-task-body
task Body (@code{ada-task-body}).
@item C-c t w
@findex ada-while
while Loop (@code{ada-while}).
@item C-c t u
@findex ada-use
use (@code{ada-use}).
@item C-c t x
@findex ada-exit
exit (@code{ada-exit}).
@item C-c t C-a
@findex ada-array
array (@code{ada-array}).
@item C-c t C-e
@findex ada-elsif
elsif (@code{ada-elsif}).
@item C-c t C-f
@findex ada-function-spec
function Spec (@code{ada-function-spec}).
@item C-c t C-k
@findex ada-package-spec
package Spec (@code{ada-package-spec}).
@item C-c t C-p
@findex ada-procedure-spec
procedure Spec (@code{ada-package-spec}.
@item C-c t C-r
@findex ada-record
record (@code{ada-record}).
@item C-c t C-s
@findex ada-subtype
subtype (@code{ada-subtype}).
@item C-c t C-t
@findex ada-task-spec
task Spec (@code{ada-task-spec}).
@item C-c t C-u
@findex ada-with
with (@code{ada-with}).
@item C-c t C-v
@findex ada-private
private (@code{ada-private}).
@item C-c t C-w
@findex ada-when
when (@code{ada-when}).
@item C-c t C-x
@findex ada-exception
exception (@code{ada-exception}).
@item C-c t C-y
@findex ada-type
type (@code{ada-type}).
@end table

@node Comment Handling
@chapter Comment Handling

By default, comment lines get indented like Ada code. There are a few
additional functions to handle comments:

@table @kbd
@item M-;
Start a comment in default column.
@item M-j
Continue comment on next line.
@item C-c ;
Comment the selected region (add @samp{--} at the beginning of lines).
@item C-c :
Uncomment the selected region
@item M-q
autofill the current comment.
@end table

@node GNU Free Documentation License
@appendix GNU Free Documentation License
@include doclicense.texi

@node Index
@unnumbered Index

@printindex fn

@bye