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 .ads or .adb, Emacs will automatically load and activate Ada mode.
Ada mode works without any customization, if you are using the GNAT compiler (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; See Other compiler, See Non-standard file names.
In addition, you may want to customize the indentation, capitalization, and other things; See Other customization.
Finally, for large Ada projects, you will want to set up an Emacs Ada mode project file for each project; See 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.
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 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 README file in the distribution.
To see what version of Ada mode you have installed, do <M-x ada-mode-version>.
The following files are provided with the Ada mode distribution:
Here we assume you are familiar with setting variables in Emacs, either thru 'customize' or in elisp (in your .emacs file). For a basic introduction to customize, elisp, and Emacs in general, see the tutorial in The GNU Emacs Manual.
These global Emacs settings are strongly recommended (put them in your .emacs):
(global-font-lock-mode t)
(transient-mark-mode t)
`(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).
`(transient-mark-mode t)' highlights selected text.
See the Emacs help for each of these variables for more information.
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 `.ads' and `.adb', respectively.
Ada mode uses the file extentions 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 unit_s.ada and unit_b.ada, respectively, you can add the following to your .emacs file:
(ada-add-extensions "_s.ada" "_b.ada")
You can define additional extensions:
(ada-add-extensions ".ads" "_b.ada")
(ada-add-extensions ".ads" ".body")
This means that whenever Ada mode looks for the body for a file whose extension is .ads, it will take the first available file that ends with either .adb, _b.ada or .body.
Simililarly, if Ada mode is looking for a spec, it will look for .ads or _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 ada-make-filename-from-adaname. Doing that
is beyond the scope of this manual; see the current definitions in
ada-mode.el and ada-xref.el for examples.
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 Project file variables for the list of project variables, and the corresponding lisp variables.
All user-settable Ada mode variables can be set via the menu `Ada | Customize'. Click on the `Help' button there for help on using customize.
To modify a specific variable, you can directly call the function
customize-variable; just type M-x customize-variable
<RET> variable-name <RET>).
Alternately, you can specify variable settings in the Emacs configuration file, .emacs. This file is coded in Emacs lisp, and the syntax to set a variable is the following:
(setq variable-name value)
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 (see 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 <Ada | Project | Edit>) shows the settings of the various project file variables referenced here.
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 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.
Check filecheck_cmd defined in the current project file. This typically
runs faster than full compile mode, speeding up finding and fixing
compilation errors.
This sets main only if it has not been set yet.
Compile filecomp_cmd from the current
project file.
This does not set main.
Set main and Buildmain to the current file, then executes the Build
command.
Show mainmain in the message buffer.
Buildmain, and links
main, by running make_cmd from the current project.
This sets main only if it has not been set yet.
Runrun_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 <C-u> before invoking the command.
This command is not available for a cross-compilation toolchain.
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 <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, <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 main:
main to
the current file.
main and
main, and click <[save]>
main
The Check file, Compile file, and Build commands
all place compilation errors in a separate buffer named
*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 <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 C-x ` key (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 <RET>.
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 `*.adp' are different than GNAT compiler project files `*.gpr'. However, Emacs Ada mode can use a GNAT project 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.
Project files have a simple syntax; they may be edited directly. Each line specifies a project variable name and its value, separated by “=”:
src_dir=/Projects/my_project/src_1
src_dir=/Projects/my_project/src_2
Some variables (like src_dir) are lists; multiple occurances
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 (see 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
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:
ada-prj-default-project-file is set, use that.
ada-prj-file-extension (default ".adp").
This algorithm always sets 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 <Ada | Project | Load ...>.
Or, in lisp, evaluate (ada-set-default-project-file "/path/file.adp").
This sets ada-prj-default-project-file, and reads the project file.
You can also specify a GNAT project file to <Ada | Project | Load
...> or ada-set-default-project-file. Emacs Ada mode checks the
file extension; if it is .gpr, the file is treated as a GNAT
project file. Any other extension is treated as an Emacs Ada mode
project file.
The project file editor is invoked with the menu `Ada | Projects | Edit'.
Once in the buffer for editing the project file, you can save your modification using the `[save]' button at the bottom of the buffer, or the C-x C-s binding. To cancel your modifications, kill the buffer or click on the `[cancel]' button.
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
comp_cmd contains ${comp_opt}, the value of the
comp_opt variable will be substituted when comp_cmd is
used.
In addition, process environment variables can be referenced using the
same syntax, or the normal $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 ${build_dir}.
Here is the list of variables. In the default values, the current
directory "." is the project file directory.
ada_project_path_sep [default: ":" or ";"]ADA_PROJECT_PATH. It defaults to the correct
value for a native implementation of GNAT for the current operating
system. The user must override this when using Windows native GNAT
with Cygwin Emacs, and perhaps in other cases.
Lisp variable: ada-prj-ada-project-path-sep.
ada_project_path [default: ""]If set, the ADA_PROJECT_PATH process environment variable is
set to this value in the Emacs process when the Emacs Ada mode project
is selected via menu `Ada | Project | Load'.
For ada_project_path, relative file paths are expanded to
absolute when the Emacs Ada project file is read, rather than when the
project file is selected.
For example if the project file is in the directory
/home/myproject, the environment variable GDS_ROOT is
set to /home/shared, and the project file contains:
ada_project_path_sep=:
ada_project_path=$GDS_ROOT/makerules
ada_project_path=../opentoken
the environment variable ADA_PROJECT_PATH will be set to
"/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.
bind_opt [default: ""]Lisp variable: ada-prj-default-bind-opt.
build_dir [default: "."]casing [default: ("~/.emacs_case_exceptions")ada-case-exception-file for more info.
Lisp variable: ada-case-exception-file.
check_cmd [default: "${cross_prefix}gnatmake -u -c -gnatc ${gnatmake_opt} ${full_current} -cargs ${comp_opt}"]full_current.
Lisp variable: ada-prj-default-check-cmd
comp_cmd [default: "${cross_prefix}gnatmake -u -c ${gnatmake_opt} ${full_current} -cargs ${comp_opt}"]full_current.
Lisp variable: ada-prj-default-comp-cmd.
comp_opt [default: "-gnatq -gnatQ"]If source code for the project is in multiple directories, the appropriate compiler options must be added here. Set source search path for examples of this. Alternately, GNAT project files may be used; Use GNAT project file.
Lisp variable: ada-prj-default-comp-opt.
cross_prefix [default: ""]debug_cmd [default: "${cross_prefix}gdb ${main}"]Lisp variable: ada-prj-default-debugger.
debug_post_cmd [default: ""]debug_cmd.
debug_pre_cmd [default: "cd ${build_dir}"]debug_cmd.
gnatfind_opt [default: "-rf"]Lisp variable: ada-prj-gnatfind-switches.
gnatmake_opt [default: "-g"]Lisp variable: ada-prj-default-gnatmake-opt.
gpr_file [default: ""]If set, the source and object directories specified in the GNAT
project file are appended to src_dir and obj_dir. This
allows specifying Ada source directories with a GNAT project file, and
other source directories with the Emacs project file.
In addition, -P{gpr_file} is added to the project variable
gnatmake_opt whenever it is referenced. With the default
project variables, this passes the project file to all gnatmake
commands.
Lisp variable: ada-prj-default-gpr-file.
link_opt [default: ""]Lisp variable: ada-prj-default-link-opt.
main [default: current file]make_cmd [default: "${cross_prefix}gnatmake -o ${main} ${main} ${gnatmake_opt} -cargs ${comp_opt} -bargs ${bind_opt} -largs ${link_opt}"]Lisp variable: ada-prj-default-make-cmd.
obj_dir [default: "."]The compiler commands must place the `.ali' files in one of these
directories; the default commands do that.
remote_machine [default: ""]run_cmd [default: "./${main}"]src_dir [default: "."]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 See Installation.
This example uses no project files.
First, create a directory Example_1, containing:
hello.adb:
with Ada.Text_IO;
procedure Hello
is begin
Put_Line("Hello from hello.adb");
end Hello;
Yes, this is missing “use Ada.Text_IO;” - we want to demonstrate compiler error handling.
hello_2.adb:
with Hello_Pkg;
procedure Hello_2
is begin
Hello_Pkg.Say_Hello;
end Hello_2;
This file has no errors.
hello_pkg.ads:
package Hello_Pkg is
procedure Say_Hello;
end Hello_Pkg;
This file has no errors.
hello_pkg.adb:
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;
Yes, this is missing the keyword body; another compiler error
example.
In buffer hello.adb, invoke <Ada | Check file>. You should
get a *compilation* buffer containing something like (the
directory paths will be different):
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
If you have enabled font-lock, the lines with actual errors (starting with hello.adb) are highlighted, with the file name in red.
Now type <C-x `> (on a PC keyboard, <`> is next to <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 hello.adb buffer.
To fix the error, change the line to be
Ada.Text_IO.Put_Line ("hello from hello.adb"):
Now invoke <Ada | Show main>; this displays Ada mode main: hello.
Now (in buffer hello.adb), invoke <Ada | Build>. You are prompted to save the file (if you haven't already). Then the compilation buffer is displayed again, containing:
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
The compilation has succeeded without errors; hello.exe now exists in the same directory as hello.adb.
Now invoke <Ada | Run>. A *run* buffer is displayed, containing
Hello from hello.adb
Process run finished
That completes the first part of this example.
Now we will compile a multi-file project. Open the file hello_2.adb, and invoke <Ada | Set main and Build>. This finds an error in hello_pkg.adb:
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
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; See Set source search path, or a GNAT project file; Use GNAT project file.
Invoke <Ada | Show main>; this displays Ada mode main: hello_2.
Move to the error with <C-x `>, and fix the error by adding body:
package body Hello_Pkg is
Now, while still in hello_pkg.adb, invoke <Ada | Build>.
gnatmake successfully builds hello_2. This demonstrates that
Emacs has remembered the main file, in the project variable
main, and used it for the Build command.
Finally, again while in hello_pkg.adb, invoke <Ada | Run>.
The *run* buffer displays Hello from hello_pkg.adb.
One final point. If you switch back to buffer hello.adb, and
invoke <Ada | Run>, hello_2.exe will be run. That is
because main is still set to hello_2, as you can
see when you invoke <Ada | Project | Edit>.
There are three ways to change main:
main to
the current file.
main and
main, and click <[save]>
main
This example illustrates using an Emacs Ada mode project file to set a compiler option.
If you have files from Example_1 open in Emacs, you should close them so you don't get confused. Use menu <File | Close (current buffer)>.
In directory Example_2, create these files:
hello.adb:
with Ada.Text_IO;
procedure Hello
is begin
Put_Line("Hello from hello.adb");
end Hello;
This is the same as hello.adb from Example_1. It has two
errors; missing “use Ada.Text_IO;”, and no space between
Put_Line and its argument list.
hello.adp:
comp_opt=-gnatyt
This tells the GNAT compiler to check for token spacing; in particular, there must be a space preceding a parenthesis.
In buffer hello.adb, invoke <Ada | Project | Load...>, and select Example_2/hello.adp.
Then, again in buffer hello.adb, invoke <Ada | Set main and
Build>. You should get a *compilation* buffer containing
something like (the directory paths will be different):
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
Compare this to the compiler output in No project files; the
gnatmake option -cargs -gnatq -gnatQ has been replaced by
-cargs -gnaty, and an additional error is reported in
hello.adb on line 4. This shows that hello.adp is being
used to set the compiler options.
Fixing the error, linking and running the code proceed as in No project files.
In this example, we show how to deal with files in more than one directory. We start with the same code as in No project files; create those files (with the errors present)
Create the directory Example_3, containing:
hello_pkg.ads:
package Hello_Pkg is
procedure Say_Hello;
end Hello_Pkg;
hello_pkg.adb:
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;
These are the same files from example 1; hello_pkg.adb has an error on line 2.
In addition, create a directory Example_3/Other, containing these files:
Other/hello_3.adb:
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;
There are no errors in this file.
Other/other.adp:
src_dir=..
comp_opt=-I..
Note that there must be no trailing spaces.
In buffer hello_3.adb, invoke <Ada | Project | Load...>, and select Example_3/Other/other.adp.
Then, again in hello_3.adb, invoke <Ada | Set main and
Build>. You should get a *compilation* buffer containing
something like (the directory paths will be different):
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
Compare the -cargs option to the compiler output in Set compiler options; this shows that other.adp is being used to
set the compiler options.
Move to the error with <C-x `>. Ada mode searches the list of
directories given by src_dir for the file mentioned in the
compiler error message.
Fixing the error, linking and running the code proceed as in No project files.
In this example, we show how to use a GNAT project file, with no Ada mode project file.
Create the directory Example_4, containing:
hello_pkg.ads:
package Hello_Pkg is
procedure Say_Hello;
end Hello_Pkg;
hello_pkg.adb:
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;
These are the same files from example 1; hello_pkg.adb has an error on line 2.
In addition, create a directory Example_4/Gnat_Project, containing these files:
Gnat_Project/hello_4.adb:
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;
There are no errors in this file.
Gnat_Project/hello_4.gpr:
Project Hello_4 is
for Source_Dirs use (".", "..");
end Hello_4;
In buffer hello_4.adb, invoke <Ada | Project | Load...>, and select Example_4/Gnat_Project/hello_4.gpr.
Then, again in hello_4.adb, invoke <Ada | Set main and
Build>. You should get a *compilation* buffer containing
something like (the directory paths will be different):
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
Compare the gcc options to the compiler output in Set compiler options; this shows that hello_4.gpr is being used to
set the compiler options.
Fixing the error, linking and running the code proceed as in No 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 Example_4 as specified in Use GNAT project file.
Create the directory Example_5, containing:
hello_5.adb:
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;
There are no errors in this file.
hello_5.adp:
ada_project_path=../Example_4/Gnat_Project
gpr_file=hello_5.gpr
hello_5.gpr:
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;
In buffer hello_5.adb, invoke <Ada | Project | Load...>, and select Example_5/hello_5.adp.
Then, again in hello_5.adb, invoke <Ada | Set main and
Build>. You should get a *compilation* buffer containing
something like (the directory paths will be different):
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
Now type <C-x `>. Example_4/hello_pkg.adb is shown, demonstrating that hello_5.gpr and hello_4.gpr are being used to set the compilation search path.
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.
ada-next-procedure).
ada-previous-procedure).
end (ada-move-to-start). If
point is at the end of a subprogram, this command jumps to the
corresponding begin if the user option
ada-move-to-declaration is nil (default), otherwise it jumps to
the subprogram declaration.
ada-move-to-end).
ff-find-other-file). If point is in a subprogram, position
point on the corresponding declaration or body in the other file.
ada-find-references). Use
C-x ` (next-error) to visit each reference (as for
compilation errors).
If the ada-xref-create-ali variable is non-nil, Emacs
will try to run GNAT for you whenever cross-reference information is
needed, and is older than the current source file.
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 `my_identifier', `my_subprogram' are the only words starting with `my' in any of the opened files, then you will have this scenario:
You type: my<M-/>
Emacs inserts: `my_identifier'
If you press <M-/> once again, Emacs replaces `my_identifier' with
`my_subprogram'.
Pressing <M-/> once more will bring you back to `my_identifier'.
This is a very fast way to do completion, and the casing of words will also be respected.
The second method (<C-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.
Ada mode comes with a full set of rules for automatic indentation. You can also configure the indentation, via the following variables:
ada-broken-indent (default value: 2)ada-indent (default value: 3)ada-indent-record-rel-type (default value: 3)record relative to type or use.
ada-indent-return (default value: 0)return relative to function (if
ada-indent-return is greater than 0), or the open parenthesis
(if 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 function with the value of ada-broken-indent.
ada-label-indent (default value: -4)ada-stmt-end-indent (default value: 0)end keyword on a separate line.
ada-when-indent (default value: 3)when relative to exception or case.
ada-indent-is-separate (default value: t)nil means indent is separate or is abstract if on a single line.
ada-indent-to-open-paren (default value: t)nil means indent according to the innermost open parenthesis.
ada-indent-after-return (default value: t)nil means that the current line will also be re-indented
before inserting a newline, when you press <RET>.
Most of the time, the indentation will be automatic, i.e when you press <RET>, the cursor will move to the correct column on the next line.
You can also indent single lines, or the current region, with <TAB>.
Another mode of indentation exists that helps you to set up your indentation scheme. If you press C-c <TAB>, Ada mode will do the following:
The exact indentation of the current line is the same as the one for the reference line, plus an offset given by the variable.
ada-format-paramlist).
This aligns the declarations on the colon (`:') separating
argument names and argument types, and aligns the in,
out and in out keywords.
Casing of identifiers, attributes and keywords is automatically
performed while typing when the variable 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:
ada-case-keyword, ada-case-attribute and
ada-case-identifier.
All these variables can have one of the following values:
downcase-wordMy_vARIable is
converted to my_variable.
upcase-wordMy_vARIable is
converted to MY_VARIABLE.
ada-capitalize-wordMy_vARIable
is converted to My_Variable.
ada-loose-case-wordMy_vARIable is converted
to My_VARIable.
Ada mode allows you to define exceptions to these rules, in a file
specified by the variable variable ada-case-exception-file
(default ~/.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 (<*>), it defines the casing af a word fragemnt (or “substring”); part of a word between two underscores or word boundary.
For example:
DOD Department of Defense
*IO
GNAT The GNAT compiler from Ada Core Technologies
The word fragment *IO applies to any word containing “_io”;
Text_IO, Hardware_IO, etc.
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 `Ada | Edit | Create Case
Exception', or press C-c C-y (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 `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 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.
ada-adjust-case-buffer).
ada-create-case-exception)
ada-case-exception-file (ada-case-read-exceptions).
Templates are defined for most Ada statements, using the Emacs “skeleton” package. They can be inserted in the buffer using the following commands:
ada-exception-block).
ada-case).
ada-declare-block).
ada-else).
ada-for-loop).
ada-header).
ada-if).
ada-package-body).
ada-loop).
ada-subprogram-body).
ada-task-body).
ada-while).
ada-use).
ada-exit).
ada-array).
ada-elsif).
ada-function-spec).
ada-package-spec).
ada-package-spec.
ada-record).
ada-subtype).
ada-task-spec).
ada-with).
ada-private).
ada-when).
ada-exception).
ada-type).
By default, comment lines get indented like Ada code. There are a few additional functions to handle comments:
ada-adjust-case-buffer: Automatic Casingada-array: Statement Templatesada-case: Statement Templatesada-case-read-exceptions: Automatic Casingada-complete-identifier: Identifier completionada-create-case-exception: Automatic Casingada-declare-block: Statement Templatesada-else: Statement Templatesada-elsif: Statement Templatesada-exception: Statement Templatesada-exception-block: Statement Templatesada-exit: Statement Templatesada-find-references: Moving Through Ada Codeada-for-loop: Statement Templatesada-format-paramlist: Formatting Parameter Listsada-function-spec: Statement Templatesada-goto-declaration: Moving Through Ada Codeada-header: Statement Templatesada-if: Statement Templatesada-loop: Statement Templatesada-move-to-end: Moving Through Ada Codeada-move-to-start: Moving Through Ada Codeada-next-package: Moving Through Ada Codeada-next-procedure: Moving Through Ada Codeada-package-body: Statement Templatesada-package-spec: Statement Templatesada-previous-package: Moving Through Ada Codeada-previous-procedure: Moving Through Ada Codeada-private: Statement Templatesada-procedure-spec: Statement Templatesada-record: Statement Templatesada-subprogram-body: Statement Templatesada-subtype: Statement Templatesada-task-body: Statement Templatesada-task-spec: Statement Templatesada-type: Statement Templatesada-use: Statement Templatesada-when: Statement Templatesada-while: Statement Templatesada-with: Statement Templates