Plugin API documentation

You can generate documentation for the plugin API using the doxygen tool:

• Pass the --enable-api-docs option to configure.
• Run make from the doc/ subdirectory.

The documentation will be output to doc/reference/index.html. Alternatively you can view the API documentation online at https://www.geany.org/manual/reference/.

Keeping the plugin ABI stable

In general the ABI changes as little as we can manage. The ABI number must match exactly between Geany and plugins, so an ABI change breaks all plugins until they are re-compiled. But sometimes it is absolutely necessary. Removing a feature or significantly changing the semantics of an existing feature require an ABI change since existing plugins may no longer work with the modified version of Geany.

The API identifying number is increased whenever anything is added to the API so plugins can test if the feature is available. The API number required by a plugin needs only to be lower than the API Geany provides, so an increase in API number without a change in ABI will not stop plugins that need a lower number from working.

If you're reordering or changing existing elements of structs that are used as part of the plugin API, you must increment GEANY_ABI_VERSION in plugindata.h. This is usually not needed if you're just appending fields to structs. The GEANY_API_VERSION value should be incremented for any changes to the plugin API, including appending elements.

If you're in any doubt when making changes to plugin API code, just ask us.

Plugin API/ABI design

You should not make plugins rely on the size of a struct. This means:

• Don't let plugins allocate any structs (stack or heap).
• Don't let plugins index any arrays of structs.
• Don't add any array fields to structs in case we want to change the array size later.

Doc-comments

• The @file tag can go in the source .c file, but use the .h header name so it appears normally in the generated documentation. See ui_utils.c for an example.
• Function doc-comments should always go in the source file, not the header, so they can be updated if/when the implementation changes.

Compiler options & warnings

Use CFLAGS='-Wfoo' ./configure or CFLAGS='-Wfoo' ./autogen.sh to set warning options (as well as anything else e.g. -g -O2).

• Enable warnings - for gcc use '-Wall -Wextra' (and optionally -Wno-unused-parameter to avoid unused parameter warnings in Glade callbacks). Alternatively you can use the Glib macro G_GNUC_UNUSED to suppress warnings on single parameters, e.g. void examplefunction(G_GNUC_UNUSED gchar *foo). Also see https://developer.gnome.org/glib/stable/glib-Miscellaneous-Macros.html.
• You should try to write ISO C99 code for portability, so always use C /* */ comments and function_name(void) instead of function_name(). This is for compatibility with various Unix-like compilers. You should use -std=c99 to help check this.

Style

• We use a tab width of 4 and indent completely with tabs not spaces. Note the documentation files use (4) spaces instead, so you may want to use the 'Detect from file' indent pref.
• Do not add whitespace at the end of lines, this adds to commit noise. When editing with Geany set preference files->Strip trailing spaces and tabs.
• Use the multiline comment /* */ to comment small blocks of code, functions descriptions or longer explanations of code, etc. The more comments are in your code the better. (See also scripts/fix-cxx-comments.pl in Git).
• Lines should not be longer than about 100 characters and after 100 characters the lines should be wrapped and indented once more to show that the line is continued.
• We don't put spaces between function names and the opening brace for argument lists.
• Variable declarations come first after an opening brace, then one newline to separate declarations and code.
• 2-operand operators should have a space each side.
• Function bodies should have 2 blank newlines after them.
• Align braces together on separate lines.
• Don't put assignments in 'if/while/etc' expressions except for loops, for example for (int i = 0; i < some_limit; i++).
• if statements without brace bodies should have the code on a separate line, then a blank line afterwards.
• Use braces after if/while statements if the body uses another if/while statement.
• Try to fit in with the existing code style.

Example:

struct Bar;

typedef struct Foo  /* struct names normally are the same as typedef names */
{
    gint    foo;    /* names are somewhat aligned visually */
    gint    bar;    /* fields don't share the same line */
    SomeLongTypeName baz; /* alignment is not strict */
    gchar   *ptr;   /* pointer symbol must go next to variable name, not type */
    Bar     public; /**< only plugin API fields have a doc-comment */
}
Foo;


gint some_func(void);

gint some_other_func(void);


/* optional function comment explains something important */
gint function_long_name(gchar arg1, <too many args to fit on this line>,
        gchar argN)
{
    /* variable declarations always go before code in each scope */
    /* variable names should NOT be aligned at all */
    gint foo, bar;  /* variables can go on the same line */
    gint baz;       /* but often don't */
    gchar *ptr;     /* pointer symbol must go next to variable name, not type */
    gchar *another; /* pointers should normally go on separate lines */

    /* Some long comment block
     * taking several different
     * lines to explain */
    if (foo)
    {
        /* variables only used in one scope should normally be declared there */
        gint dir = -1;

        bar = foo;
        if ((bar & (guint)dir) != 7)
            some_code(arg1, <too many args to fit on this line>,
                argN - 1, argN);

        some_func();
    }
}


/** Explains using doc-comments for plugin API functions.
 * First line should be short and use the third person tense - 'explains',
 * not 'explain'.
 *
 * @return Some number.
 * @since 1.22. */
gint another_function(void)
{
    ...

Private Headers

If there is some data that needs to be shared between various parts of the core code, put them in a "private header", that is, if the public header is called foo.h, then make a fooprivate.h header that contains the non-public functions, types, globals, etc that are needed. Other core source files can then just include the foo.h and/or fooprivate.h depending what they need, without exposing that stuff to plugins.

Order of Includes

Inside a source file the includes section should be ordered like this:

1. Always include the config.h file at the start of every source file, for example:

   #ifdef HAVE_CONFIG_H
   # include "config.h"
   #endif
   

   This allows the Autotools and other build systems use the ./configure time settings. If you don't do this, there's likely to be a number of macros that you'll have to define in the build system or custom headers.

   Warning: Never include config.h in headers, and especially in "public" headers that plugins might include.

2. Then include the header that has the same name as the source file (if applicable). For example, for a source file named foo.c, include the foo.h below the config.h include. If there is a fooprivate.h, foo.c will most likely want to include that too, put it in with includes in #3.

3. At this point, it should be safe to include all the headers that declare whatever is needed. If everything generally "includes what it uses" and all files included contain the appropriate multiple-declaration guards then the order of includes is fairly arbitrary. Prefer to use English alphabetic order if possible.

4. By now it doesn't really matter about the order, nothing below here is "our problem". Semi-arbitrarily, you should use an include order like this:

   1. Standard C headers
   2. Non-standard system headers (eg. windows.h or unistd.h)
   3. GLib/GTK+ or related headers

5. Everything else that should not influence 1-4.

Including in Header Files

Headers should also include what they use. All of the types should defined in order to allow the header to be included stand-alone. For example, if a header uses a GtkWidget*, it should #include <gtk/gtk.h>. Or, if a headers uses a GPtrArray*, it should #include <glib.h> to ensure that all of the types are declared, whether by pointers/opaquely or fully, as required. Since all headers will use a G_BEGIN_DECLS and G_END_DECLS guard for C++, the bare minimum for a header is to include glib.h or <gtk/gtk.h> or gtkcompat.h or some other header that makes those macros available.

Commit messages

Follow the standard Git formatting:

• No line should use more than about 80 characters (around 72 is best).

• The first line is the commit's summary and is followed by an empty line. This summary should be one line and one line only, thus less than 80 characters. This summary should not include any punctuation unless really needed. See it as the subject of an email: keep it concise and as precise as you can, but not tool long.

• Following lines are optional detailed commit information, with paragraphs separated by blank lines. This part should be as long as needed to describe the commit in depth, should use proper punctuation and should include any useful information, like the motivation for the patch and/or any valuable details the diff itself don't provide or don't make clear. Make it as complete as you think it makes sense, but don't include an information that is better explained by the commit's diff.

  It is OK to use ASCII formatting like bullet list using "*" or "-", etc. if useful, but emphasis (bold, italic, underline) should be avoided.

Example:

Ask the user if spawn fails in utils_open_browser()

Ask the user to configure a valid browser command if spawning it
fails rather than falling back to some arbitrary hardcoded defaults.

This avoid spawning an unexpected browser when the configured one is
wrong, and gives the user a chance to correctly fix the preference.

filetypes.* configuration file

All languages need a data/filetypes.foo configuration file. See the "Filetype definition files" section in the manual and/or data/filetypes.c for an example.

Programming languages should have:

• [keywords] if the lexer supports it.
• [settings] mostly for comment settings.
• [build-menu] (or [build_settings]) for commands to run.

For languages with a Scintilla lexer, there should be a [styling] section, to correspond to the styles used in highlighting_styles_FOO[] in highlightingmappings.h - see below.

Don't forget to add the newly created filetype file to data/Makefile.am.

Syntax highlighting

It may be possible to use an existing Scintilla lexer in the scintilla/ subdirectory - if not, you will need to find (or write) one, LexFoo.cxx. Try the official Scintilla project first.

When adding a lexer:

• add LexFoo.cxx to scintilla/lexilla/lexers
• add &lmFoo to scintilla/lexilla/src/Lexilla.cxx and scintilla/scintilla_changes.patch
• update scintilla/Makefile.am and meson.build

For syntax highlighting, you will need to edit highlighting.c and highlightingmappings.h and add the following things:

1. In highlightingmappings.h:

   1. define highlighting_lexer_FOO to the Scintilla lexer ID for this filtype, e.g. SCLEX_CPP.
   2. define the highlighting_styles_FOO array that maps Scintilla style states to style names in the configuration file.
   3. define highlighting_keywords_FOO to EMPTY_KEYWORDS if the filtype has no keywords, or as an HLKeyword array mapping the Scintilla keyword IDs to names in the configuration file.
   4. define highlighting_properties_FOO to EMPTY_PROPERTIES, or as an array of HLProperty if the filetype requires some lexer properties to be set. However, note that properties should normally be set in the [lexer_properties] section of the configuration file instead.

   You may look at other filtype's definitions for some examples (Ada, CSS or Diff being good examples).

2. In highlighting.c:

   1. Add init_styleset_case(FOO); in highlighting_init_styles().
   2. Add styleset_case(FOO); in highlighting_set_styles().

3. Write data/filetypes.foo configuration file [styling] section. See the manual and see data/filetypes.d for a named style example.

Error message parsing

New-style error message parsing is done with an extended GNU-style regex stored in the filetypes.foo file - see the [build_settings] information in the manual for details.

Old-style error message parsing is done in msgwin_parse_compiler_error_line() of msgwindow.c - see the ParseData typedef for more information.

Other features

If the lexer has comment styles, you should add them in highlighting_is_comment_style(). You should also update highlighting_is_string_style() for string/character styles. For now, this prevents calltips and autocompletion when typing in a comment (but it can still be forced by the user).

For brace indentation, update lexer_has_braces() in editor.c; indentation after ':' is done from on_new_line_added().

If the Scintilla lexer supports user type keyword highlighting (e.g. SCLEX_CPP), update document_update_tags() in document.c.

Adding a CTags parser

This assumes the filetype for Geany already exists.

First write or find a CTags compatible parser, foo.c. Check this fork: https://github.com/universal-ctags/ctags

$ geany -g tmp.ext.tags tests/ctags/mytest.ext
$ scripts/print-tags.py < tmp.ext.tags > tests/ctags/mytest.ext.tags

Stop on warnings

When a GLib or GTK warning is printed, often you want to get a backtrace to find out what code caused them. You can do that with the --g-fatal-warnings argument, which will abort Geany on the first warning it receives.

But for ordinary testing, you don't always want your editor to abort just because of a warning - use:

(gdb) b handler_log if level <= G_LOG_LEVEL_WARNING

Running with batch commands

Use:

$ gdb src/geany -x gdb-commands

Where gdb-commands is a file with the following lines:

set pagination off
b handler_log if level <= G_LOG_LEVEL_WARNING
r -v

Loading a plugin

This is useful so you can load plugins without installing them first. Alternatively you can use a symlink in ~/.config/geany/plugins or $prefix/lib/geany (where $prefix is /usr/local by default).

The gdb session below was run from the toplevel Geany source directory. Start normally with e.g. "gdb src/geany". Type 'r' to run. Press Ctrl-C from the gdb window to interrupt program execution.

Example:

Program received signal SIGINT, Interrupt.
0x00d16402 in __kernel_vsyscall ()
(gdb) call plugin_new("./plugins/.libs/demoplugin.so")
** INFO: Loaded:   ./plugins/.libs/demoplugin.so (Demo)
$1 = (Plugin *) 0x905a890
(gdb) c
Continuing.

Program received signal SIGINT, Interrupt.
0x00d16402 in __kernel_vsyscall ()
(gdb) call plugin_free(0x905a890)
** INFO: Unloaded: ./plugins/.libs/demoplugin.so
(gdb) c
Continuing.

Building Plugins

The geany-plugins autotools script automatically detects the installed system Geany and builds the plugins against that.

To use plugins with a development version of Geany built with a different prefix, the plugins will need to be compiled against that version if the ABI has changed.

To do this you need to specify both --prefix and --with-geany-libdir to the plugin configure. Normally the plugin prefix is the same as the Geany prefix to keep plugins with the version of Geany that they are compiled against, and with-geany-libdir is the Geany prefix/lib.

Whilst it is possible for the plugin prefix to be different to the prefix of the libdir (which is why there are two settings), it is probably better to keep the version of Geany and its plugins together.