GLIB-GENMARSHAL(1) User Commands GLIB-GENMARSHAL(1)

NAME

glib-genmarshal - C code marshaller generation utility for GLib
closures

SYNOPSIS

glib-genmarshal [OPTION...] [FILE...]

DESCRIPTION

glib-genmarshal is a small utility that generates C code marshallers
for callback functions of the GClosure mechanism in the GObject
sublibrary of GLib. The marshaller functions have a standard
signature, they get passed in the invoking closure, an array of value
structures holding the callback function parameters and a value
structure for the return value of the callback. The marshaller is
then responsible to call the respective C code function of the
closure with all the parameters on the stack and to collect its
return value.

glib-genmarshal takes a list of marshallers to generate as input. The
marshaller list is either read from files passed as additional
arguments on the command line; or from standard input, by using - as
the input file.

Marshaller list format

The marshaller lists are processed line by line, a line can contain a
comment in the form of

or a marshaller specification of the form

RTYPE:PTYPE
RTYPE:PTYPE,PTYPE
RTYPE:PTYPE,PTYPE,PTYPE

The RTYPE part specifies the callback's return type and the PTYPEs
right to the colon specify the callback's parameter list, except for
the first and the last arguments which are always pointers.

Parameter types

Currently, the following types are supported:

VOID
indicates no return type, or no extra parameters. If VOID is used
as the parameter list, no additional parameters may be present.

BOOLEAN
for boolean types (gboolean)

CHAR
for signed char types (gchar)

UCHAR
for unsigned char types (guchar)

INT
for signed integer types (gint)

UINT
for unsigned integer types (guint)

LONG
for signed long integer types (glong)

ULONG
for unsigned long integer types (gulong)

INT64
for signed 64bit integer types (gint64)

UINT64
for unsigned 64bit integer types (guint64)

ENUM
for enumeration types (gint)

FLAGS
for flag enumeration types (guint)

FLOAT
for single-precision float types (gfloat)

DOUBLE
for double-precision float types (gdouble)

STRING
for string types (gchar*)

BOXED
for boxed (anonymous but reference counted) types (GBoxed*)

PARAM
for GParamSpec or derived types (GParamSpec*)

POINTER
for anonymous pointer types (gpointer)

OBJECT
for GObject or derived types (GObject*)

VARIANT
for GVariant types (GVariant*)

NONE
deprecated alias for VOID

BOOL
deprecated alias for BOOLEAN

OPTIONS

--header
Generate header file contents of the marshallers. This option is
mutually exclusive with the --body option.

--body
Generate C code file contents of the marshallers. This option is
mutually exclusive with the --header option.

--prefix=PREFIX
Specify marshaller prefix. The default prefix is
`g_cclosure_user_marshal'.

--skip-source
Skip source location remarks in generated comments.

--stdinc
Use the standard marshallers of the GObject library, and include
glib-object.h in generated header files. This option is mutually
exclusive with the --nostdinc option.

--nostdinc
Do not use the standard marshallers of the GObject library, and
skip glib-object.h include directive in generated header files.
This option is mutually exclusive with the --stdinc option.

--internal
Mark generated functions as internal, using G_GNUC_INTERNAL.

--valist-marshallers
Generate valist marshallers, for use with
g_signal_set_va_marshaller().

-v, --version
Print version information.

--g-fatal-warnings
Make warnings fatal, that is, exit immediately once a warning
occurs.

-h, --help
Print brief help and exit.

-v, --version
Print version and exit.

--output=FILE
Write output to FILE instead of the standard output.

--prototypes
Generate function prototypes before the function definition in
the C source file, in order to avoid a missing-prototypes
compiler warning. This option is only useful when using the
--body option.

--pragma-once
Use the once pragma instead of an old style header guard when
generating the C header file. This option is only useful when
using the --header option.

--include-header=HEADER
Adds a #include directive for the given file in the C source
file. This option is only useful when using the --body option.

-D SYMBOL[=VALUE]
Adds a #define C pre-processor directive for SYMBOL and its given
VALUE, or "1" if the value is unset. You can use this option
multiple times; if you do, all the symbols will be defined in the
same order given on the command line, before the symbols
undefined using the -U option. This option is only useful when
using the --body option.

-U SYMBOL
Adds a #undef C pre-processor directive to undefine the given
SYMBOL. You can use this option multiple times; if you do, all
the symbols will be undefined in the same order given on the
command line, after the symbols defined using the -D option. This
option is only useful when using the --body option.

--quiet
Minimizes the output of glib-genmarshal, by printing only
warnings and errors. This option is mutually exclusive with the
--verbose option.

--verbose
Increases the verbosity of glib-genmarshal, by printing debugging
information. This option is mutually exclusive with the --quiet
option.

USING GLIB-GENMARSHAL WITH MESON
Meson supports generating closure marshallers using glib-genmarshal
out of the box in its "gnome" module.

In your meson.build file you will typically call the
gnome.genmarshal() method with the source list of marshallers to
generate:

gnome = import('gnome')
marshal_files = gnome.genmarshal('marshal',
sources: 'marshal.list',
internal: true,
)

The marshal_files variable will contain an array of two elements in
the following order:

+o a build target for the source file

+o a build target for the header file

You should use the returned objects to provide a dependency on every
other build target that references the source or header file; for
instance, if you are using the source to build a library:

mainlib = library('project',
sources: project_sources + marshal_files,
...
)

Additionally, if you are including the generated header file inside a
build target that depends on the library you just built, you must
ensure that the internal dependency includes the generated header as
a required source file:

mainlib_dep = declare_dependency(sources: marshal_files[1], link_with: mainlib)

You should not include the generated source file as well, otherwise
it will be built separately for every target that depends on it,
causing build failures. To know more about why all this is required,
please refer to the corresponding Meson FAQ entry[1].

For more information on how to use the method, see the Meson
documentation for gnome.genmarshal()[2].

USING GLIB-GENMARSHAL WITH AUTOTOOLS
In order to use glib-genmarshal in your project when using Autotools
as the build system, you will first need to modify your configure.ac
file to ensure you find the appropriate command using pkg-config,
similarly as to how you discover the compiler and linker flags for
GLib.

PKG_PROG_PKG_CONFIG([0.28])

PKG_CHECK_VAR([GLIB_GENMARSHAL], [glib-2.0], [glib_genmarshal])

In your Makefile.am file you will typically need very simple rules to
generate the C files needed for the build.

marshal.h: marshal.list
$(AM_V_GEN)$(GLIB_GENMARSHAL) \
--header \
--output=$@ \
$<

marshal.c: marshal.list marshal.h
$(AM_V_GEN)$(GLIB_GENMARSHAL) \
--include-header=marshal.h \
--body \
--output=$@ \
$<

BUILT_SOURCES += marshal.h marshal.c
CLEANFILES += marshal.h marshal.c
EXTRA_DIST += marshal.list

In the example above, the first rule generates the header file and
depends on a marshal.list file in order to regenerate the result in
case the marshallers list is updated. The second rule generates the
source file for the same marshal.list, and includes the file
generated by the header rule.

EXAMPLE

To generate marshallers for the following callback functions:

void foo (gpointer data1,
gpointer data2);
void bar (gpointer data1,
gint param1,
gpointer data2);
gfloat baz (gpointer data1,
gboolean param1,
guchar param2,
gpointer data2);

The marshaller.list file has to look like this:

VOID:VOID
VOID:INT
FLOAT:BOOLEAN,UCHAR

and you call glib-genmarshal like this:

glib-genmarshal --header marshaller.list > marshaller.h
glib-genmarshal --body marshaller.list > marshaller.c

The generated marshallers have the arguments encoded in their
function name. For this particular list, they are

g_cclosure_user_marshal_VOID__VOID(...),
g_cclosure_user_marshal_VOID__INT(...),
g_cclosure_user_marshal_FLOAT__BOOLEAN_UCHAR(...).

They can be used directly for GClosures or be passed in as the
GSignalCMarshaller c_marshaller; argument upon creation of signals:

GClosure *cc_foo, *cc_bar, *cc_baz;

cc_foo = g_cclosure_new (NULL, foo, NULL);
g_closure_set_marshal (cc_foo, g_cclosure_user_marshal_VOID__VOID);
cc_bar = g_cclosure_new (NULL, bar, NULL);
g_closure_set_marshal (cc_bar, g_cclosure_user_marshal_VOID__INT);
cc_baz = g_cclosure_new (NULL, baz, NULL);
g_closure_set_marshal (cc_baz, g_cclosure_user_marshal_FLOAT__BOOLEAN_UCHAR);

SEE ALSO

glib-mkenums(1)

NOTES

1. corresponding Meson FAQ entry
https://mesonbuild.com/FAQ.html#how-do-i-tell-meson-that-my-
sources-use-generated-headers

2. Meson documentation for gnome.genmarshal()
https://mesonbuild.com/Gnome-module.html#gnomegenmarshal

GObject GLIB-GENMARSHAL(1)