3 .\" (C) 1999 George Lebl <jirka@5z.com>
5 .\" This manual page is covered by the terms of the GNU General
8 .TH GOB 1 "GOB @VERSION@"
10 GOB \- The GTK+ Object Builder
18 GTK+ Object Builder is a simple preprocessor for easily creating
19 GTK+ objects. It does not parse any C code and ignores any C errors. It
20 is in spirit similar to things like lex or yacc.
26 Display a simple help screen.
29 Display version information (note, --version was not added until 0.92.0)
32 Exit with an error code even when you encounter a warning.
35 Exit with an error only on errors, not on warnings, this is the default.
41 Never add the extern "C" to the header.
44 Never generate any code with GNU C extensions. However all the GNU C
45 extensions are always wrapped in #ifdef __GNUC__, so code using them compiles
46 correctly even on non-GNU compilers. This option is for purists only.
47 (using GNU extensions some warnings are eliminated, some ugly hacks and there
48 is better argument type safety, so it's good to use them)
51 Don't touch the generated header file unless it really changed, this avoids
52 spurious rebuilds, but can confuse some make systems (automake in particular),
53 so it is not enabled by default. Private header is still touched even if
56 .B --always-private-header
57 Always create a \fB<basename>-private.h\fR file, even if it would be empty.
58 Otherwise, it is only created when there are private data members in the class.
59 This option implicitly negates --no-private-header
61 .B --no-private-header
62 Never create a private header file. If we use any private data members,
63 define the private data structure at the point in the .c source where
64 the class definition begins. This option implicitly negates
65 --always-private-header
68 Do not write any output files, just check syntax of the input file.
71 Do not print out the '#line' statements into the output. Useful for debugging
72 the auto-generated generated code.
75 Do not create the Self and SelfClass type aliases and the SELF, IS_SELF
76 and SELF_CLASS macros.
78 .B --no-kill-underscores
79 Do not remove the initial underscore from method names.
81 .B --always-private-struct
82 Always include the private pointer in the public header file. This is useful for
83 files which are part of a library and you want to reserve the right to add some
84 private data members without breaking binary compatibility.
88 Because we need to parse out different parts of the typename, sometimes you
89 need to specify the typename with some special syntax. Types are specified in
90 capitalized form and words are separated by ':'. The first word of the type
91 (which can be empty) is the "namespace". This fact is for example used for the
92 type checking macro and the type macro. For "Gtk:New:Button", the macros will
93 be GTK_IS_NEW_BUTTON and GTK_TYPE_NEW_BUTTON. This colon separated format of
94 typenames is used in the class declaration header and for method argument
99 The filenames are created from the typename. The words are
100 separated by '-' and all in lower case. For example for an object named
101 "Gtk:New:Button", the files are \fBgtk-new-button.c\fR and
102 \fBgtk-new-button.h\fR.
103 If you are using C++ mode, the output .c file will in fact be a .cc file.
104 If you have any private data members, a private header file will also
105 be created, called \fB<basename>-private.h\fR (for the example above it
106 would be gtk-new-button-private.h).
107 The public header file is created to be human readable and to be used as a
108 reference to the object. The .c source file is not created as a human
109 readable source and is littered with #line statements, which make the
110 compiler attempt to point you to the right line in your .gob file in
111 case of parsing errors. The output should not be edited by hand, and
112 you should only edit the .gob file.
114 .SH INCLUDING NORMAL C CODE IN THE OUTPUT FILES
116 To include some code directly in the output C file begin with '%{'
117 on an empty line and end the code with a '%}' on an empty line. These
118 sections will appear in the output files in the order they are given.
119 There are several other \fIsections\fR to which you can put code. You can
120 put it in the 'header' section (which can be abbreviated 'h') and it will
121 go into the public header file. You can also put it in the 'privateheader'
122 section (abbreviated 'ph') which will make the code go into the private
123 header file. Sometimes you want some code (other includes) to appear before
124 the extern "C" and the protecting define. To do this you can put them
125 into the 'headertop' (or 'ht') section. You may wish to include code or
126 comments in all the files, which you can do by putting them into the 'all'
127 (or 'a') section. Similarly, code you wish to appear at the top of all
128 files go in the 'alltop' (or 'at') section. For example:
132 /* this will be on top of all output files */
136 /* this will be on top of the public header */
140 /* this will go into the private header file */
144 /* will be included in the header */
145 void somefunc(int i);
149 /* will be included in all files */
153 /* will be included in the C file */
164 Gob will automatically include the class header file at the top of the .c
165 source file. If you wish to include it somewhere else, put the include
166 into some %{ %} section above the class definition, and gob will not include
167 it automatically. This way you can avoid circular includes and control
168 where in the file do you want to include the header.
170 If you made any data members private, gob will also create a source file
171 that will be called \fB<basename>-private.h\fR. Same rule as above applies
172 for this just as it does for the regular header file. If you do explicitly
173 include the regular header file, you should always include this private
174 header file below it. That is, if you use any private data members. If you
175 don't, the private header file automatically includes the public header file,
176 and thus the public header file will be indirectly included at the very top
179 .SH MAKING A NEW CLASS
183 There can be only one class per input file. Defining a class
184 is sort of like in Java, you define the class and write inline code
185 directly into the class definition. To define a class you need to specify
186 the new object name and the name of the object from which it is derived
187 from, such as this "class <new type> from <parent type> { <class code> }".
191 class Gtk:New:Button from Gtk:Button {
199 There are five types of data members. Three of them are normal data numbers,
200 one is class wide (global) in scope and one is a virtual one, usually linked to
201 a normal data member or a class wide data member. The three normal data
202 members are public, protected and private. Public and protected are basically
203 just entries in the object structure, while private has it's own dynamically
204 allocated private structure. Protected members are always put after the public
205 one in the structure and are marked protected in the header file. There is
206 only one identifier allowed per typename unlike in normal C. Example:
210 private GtkWidget *h;
215 Public and protected data members are accessed normally as members of
216 the object struct. Example where 'i' is as above a public data member:
223 The private data members are defined in a structure which is only available
224 inside the .c file, or by including a private header file. You must access
225 them using the structure _priv. Example
226 where 'h' is the private data member (as in the above example):
229 object->_priv->h = NULL;
232 The _priv structure is defined in the \fB<basename>-private.h\fR.
233 This file is automatically included if you don't include it yourself. You
234 should always explicitly include it in your .gob file if you explicitly also
235 include the main header file. The reason it is a separate header file is
236 that you can also include it in other places that need to access this objects
237 private data, such as if you have the majority of functionality of an object
238 in a separate .c file. Or if a derived object needs to access the protected
241 In case you use the \fB--no-private-header\fR option, no
242 private header file is created and you can only access the _priv pointer
243 below the class definition in the .gob file.
245 Also note that this structure is dynamically allocated, and is freed in the
246 finalize handler. If you override the finalized handler, your code will be
247 run first and only then will the _priv structure be freed.
249 Classwide data members:
251 Sometimes you want a datamember to be shared by all objects. You then need
252 the "classwide" scope keyword. So for example the following adds a global
259 To access the member you do the standard voodoo of getting the class from the
260 object and casting it to your class pointer. Thus the following would work:
263 SELF_CLASS(GTK_OBJECT(object)->klass)->foo = 20;
267 Automatic Initialization (0.93.0 and higher only):
269 You can automatically initialize the public private and protected data members
270 without having to add an init method. The advantage here is that
271 initialization is kept close to the definition of the data member and thus
272 it's easier to check. To do this, just add a '=' followed by a number or
273 a token. It is also possible to include arbitrary C code for more elaborate
274 initializations by putting it all in curly braces. Note that the curly braces
275 will not be printed into the output, but since gob does not C parsing it needs
276 them to figure out where the C code ends. The code will be inserted into the
277 init method, above the user defined body. So for example the following
278 will initialize an integer to -1 and a string with a newly allocated string
283 private char *bar = {g_strdup("hello")};
287 Automatic Destruction (0.93.0 and higher only):
289 Most data stored as pointers needs to have a function called when the object
290 is destroyed, to either free it or give up a reference. Gob will let you
291 define a function to be called on the data the object is destroyed. This is
292 achieved by putting 'destroywith' followed by a function name after the
293 variable definition. It is only called if the data you defined this on
294 is not NULL, so you cans specify functions which do not handle NULL. It
295 is very much like the GDestroyNotify function used in GTK+ and glib in many
296 places. Unlike many other places, gob will not enforce any kind of type
297 safety here so be a little bit more careful. Any function you give it will
298 be called as a "void function(void *)". It will in fact be cast into such
299 a form before called. This is to avoid spurious warnings for gtk calls to
300 subclass methods. The function needs not be of that form exactly, it just has
301 to take one argument which is the pointer to the data. You should also not
302 define this on any non-pointer data as the results may be undefined.
306 public Gtk:Widget *window = NULL
307 destroywith gtk_widget_destroy;
308 public char *foo = {g_strdup("bar")}
312 Note that the function name you give must be a real function and not macro.
313 Also note that this is always called in the "destroy" method of GtkObject.
314 It is always called after any user defined body of the destroy handler.
316 Sometimes you may want to run arbitrary code on destruction. While this can
317 be perfectly well done in the destroy handler. Depending on the style you
318 may want to include all destruction/initialization code together with the
319 definition of the data member. Thus you may want to put arbitrary code which
320 will then be inserted into the "destroy" method of GtkObject. This can be
321 done with the "destroy" keyword followed by arbitrary code in curly braces.
322 Inside this code a macro called VAR will be define which refers to your
323 variable. So for example destroying a GString can be either done with
324 a helper routine or the following code:
327 public GString *string = {g_string_new(NULL)}
329 if(VAR) g_string_free(VAR, TRUE);
333 The thing to remember with these is that there are many ways to do this
334 and you'd better be consistent in your code in how you use the above things.
335 Also defining a helper routine that will do the destruction will be a nicer
336 thing to do if that's a possibility. The "destroy" keyword with code does
337 take up more space in the file and it may become more cluttered.
339 The data is zeroed out after being destroyed. This is to make debugging easier
340 in case your code might try to access an already destroyed object. In case
341 you have overridden the destroy method, your code will be run first and
342 only then will the destructors be called. You should not however make any
343 assumptions about the order at which the destructors are called. If you have
344 interdependencies between destructors for different data members, you will
345 have to do this in your own destroy override function.
349 The fourth type of a data member an argument type. It is a named data member
350 which is one of the features of the GTK+ object system. You need to define a
351 get and a set handler. They are fragments of C code that will be used to get
352 the value or set the value of the argument. Inside them you can use the define
353 ARG to which you assign the data or get the data. You can also use the
354 identifier "self" as pointer to the object instance. The type is defined as
355 one of the gtk type enums, but without the GTK_TYPE_ prefix. For example:
359 argument INT height set { self->height = ARG; } get { ARG = self->height; };
363 If you don't define a set or a get handler it will be a read-only
364 or a write-only argument. If you want to add extra argument flags, add
365 them into parenthesis after the argument keyword, separated by '|' and
366 without the GTK_ARG_ prefix. For example:
370 argument (CONSTRUCT) INT height get { ARG = self->height; };
373 This makes the argument settable even before the object is constructed, so
374 that people can pass it to gtk_object_new function. Useful is also
375 CONSTRUCT_ONLY flag which makes the argument only available during
376 construction of the object.
378 Since 0.92.1, gob creates macros which can be used for type safe access to
379 gtk arguments. The macros are called <type>_ARG_<argument name>(x) and
380 <type>_GET_ARG_<argument name>(x). They define both the string and the
381 value part of the argument. So for setting an argument of height, one would
382 use (for object type My:Object):
385 gtk_object_set(GTK_OBJECT(object),
386 MY_OBJECT_ARG_HEIGHT(7),
390 And for getting, you would use:
394 gtk_object_set(GTK_OBJECT(object),
395 MY_OBJECT_GET_ARG_HEIGHT(&height),
399 Note however that the type safety only works completely on GNU C compilers.
400 The code will compile on other compilers but with minimal type safety.
402 To get good type safety on POINTER types however, you should specify
403 an optional C type that gob should use. For other then POINTER types
404 this is redundant but possible. To do this, place '(type <c type>)'
405 right after the GTK+ type. Example:
408 argument POINTER (type char *) foo set { /* foo */ } get { /* bar */ };
412 Sometimes it can become tiresome to type in the set and get handlers if
413 they are trivial. So gob since version 0.93.0 provides automatic argument
414 linking to data members. There are three different cases it handles, direct
415 link (keyword 'link'), string linking (keyword 'stringlink') and object
416 linking (keyword 'objectlink'). You just place the keyword after the argument
417 name instead of the get/set handlers. It will link to a data member of the
418 same name that was defined earlier in the input file. Best is to see examples:
422 argument INT foo link;
429 argument INT (type int) foo
430 get { ARG = self->foo; }
431 set { self->foo = ARG; };
438 argument POINTER foo stringlink;
445 argument POINTER (type char *) foo
447 ARG = g_strdup(self->_priv->foo);
449 g_free(self->_priv->foo);
450 self->_priv->foo = g_strdup(ARG);
454 And for the objectlink we would have:
457 public Gtk:Object * foo;
458 argument POINTER foo objectlink;
464 protected Gtk:Object * foo;
465 argument POINTER (type Gtk:Object *) foo
470 gtk_object_unref(self->foo);
473 gtk_object_ref(self->foo);
478 As you see it will handle NULLs correctly (for the string, g_free and g_strdup
479 handle NULLs). And it will also handle private, protected and public members.
480 For objectlink, just a pointer is returned on get, if you wish to keep it around,
481 you should call gtk_object_ref on it. For stringlink, get makes a copy of
482 the string which you should free after use. This is the behaviour since 1.0.2.
486 There is a whole array of possible methods. The three normal,
487 "familiar" method types are private, protected and public. Public are
488 defined as normal functions with a prototype in the header file.
489 Protected methods are defined as normal methods (which you can call from other
490 files), but their prototype is placed in the private header file. Private
492 are defined as static functions with prototypes at the top of the .c
493 file. Then there are signal, virtual and override methods. More on those
495 define init and class_init methods with a special definition if you want
496 to add code to the constructors or you can just leave them out.
497 You can also not define a body for a method, by just using ';' instead of a
498 body. This will define an empty function. You can't do this for non-void
499 regular public, private or protected methods, however it is acceptable for
500 non-void virtual, signal and override methods.
502 Function argument lists:
504 For all but the init and class_init methods, you use the
505 following syntax for arguments. The first argument can be just "self",
506 which gob will translate into a pointer to the object instance. The rest
507 of the arguments are very similar to normal C arguments. If the
508 typename is an object pointer you should use the syntax defined above
509 with the words separated by ':'
513 <type> <argument id> (check <list of checks>)
516 The checks are glib type preconditions, and can be the following:
517 "null", which tests pointers for being NULL, "type" which checks GTK+
518 object pointers for being the right type, "<test> <number>" which tests
519 numeric arguments for being a certain value. The test can be a <,>,<=,>=
523 public int foo(self, int h (check > 0 < 11), Gtk:Widget *w (check null type))
527 This will be the prototype of a function which has a self pointer
528 as the first argument, an integer argument which will be checked and has
529 to be more then 0 and less then 11, and a pointer to a GtkWidget object
530 instance and it is checked for being null and the type will also be
535 Methods which have a return value, there also has to be something
536 returned if there is an error, such as if a precondition is not met. The
537 default is 0, casted to the type of the method. If you need to return
538 something else then you can specify an "onerror" keyword after the
539 prototype and after that a number, a token (an identifier) or a bit of C
540 code enclosed in braces {}. The braces will not be printed into the
541 output, they just delimit the string. For example:
544 public void * get_something(self, int i (check >= 0)) onerror NULL {
549 The onerror value is also used in overrides that have a return value, in
550 case there isn't a parent method, PARENT_HANDLER will return it. More about
555 Some signal and virtual methods have a return type. But what happens if
556 there is no default handler and no one connects to a signal. GOB will
557 normally have the wrappers return whatever you specify with onerror or '0'
558 if you haven't specified anything. But since 0.93.2 you can specify a default
559 return value with the keyword 'defreturn'. It's use is identical to the
560 use of onerror, and you can in fact use both at the same time. Example
563 virtual int get_some_int(self) onerror -1 defreturn 10 ;
566 That is an empty virtual method (in C++ terms a pure virtual). If you never
567 specify any handler for it in the derived children it will just return 10.
571 There are two methods that handle the construction of an object, init and
572 class_init. You define them by just using the init or class_init keyword
573 with an untyped argument in the argument list. The argument will be
574 usable in your function as a pointer to your object or class depending if
575 it's init or class_init.
580 /* initialize the object here */
586 /* initialize the class, this is rarely needed */
591 The class_init function is very rarely needed as all standard class
592 initialization is taken care of for you by gob itself. The init function
593 should on the other hand be used whenever you need to construct or initialize
594 anything in the object to put it into a sane state. Sometimes you need
595 some arguments, for this you should either use a construct method and a
596 new function like many GTK+ widgets, and/or a CONSTRUCT or CONSTRUCT_ONLY
601 Virtual methods are basically pointers in the class structure,
602 so that one can override the method in derived methods. They can be empty
603 (if you put ';' instead of the C code). A wrapper will also be defined
604 which makes calling the methods he same as public methods. This type of
605 method is just a little bit "slower" then normal functions, but not as
606 slow as signals. You define them by using "virtual" keyword before the
607 prototype. If you put the keyword "private" right after the "virtual"
608 keyword, the wrapper will not be a public method, but a private one.
609 You can do the same with "protected" to make a protected wrapper.
613 Signals are methods to which the user can bind other handlers
614 and override the default handler. The default handler is basically the
615 method body. This is the most versatile and flexible type of a method
616 and also the slowest. You need to specify a whole bunch of things when
617 you define a signal. One thing is when the default handler will be run,
618 first or last. You specify that by "first" or "last" right after the
619 "signal" keyword. Then you need to define the gtk enum types (again
620 without the GTK_TYPE_ prefix). For that you define the return types
621 and the types of arguments after the "self" pointer (not including the
622 "self" pointer). You put it in the following syntax "<return type> (<list
623 of arguments>)". If the return type is void, the type should be "NONE",
624 the same should be for the argument list. The rest of the prototype is
625 the same as for other method types. The body can also be empty, and
626 also there is a public method wrapper which you can use for calling the
627 signal just like a public method. Example:
630 signal first INT(POINTER,INT)
631 int do_something(self, Gtk:Widget *w (check null type), int length)
640 signal last NONE(NONE) void foo(self);
644 If you don't want the wrapper that emits the signal to be public, you can
645 include the keyword "private" after the "signal" keyword. This will make
646 the wrapper a normal private method. You can also make a protected wrapper
647 by using "protected" instead of "private".
649 If you don't define a "first" or a "last", the default will be taken as
652 You can also add additional flags. You do this just like with the argument
653 flags, although this is probably very rare. These are the GTK_RUN_* flags,
654 and you can add them without the GTK_RUN_ prefix into a parenthesis, just
655 after the "signal" keyword. By default all public signals are GTK_RUN_ACTION.
659 If you need to override some method (a signal or a virtual method
660 of some class in the parent tree of the new object), you can define and
661 override method. After the "override" keyword, you should put the
662 typename of the class you are overriding a method from. Other then that
663 it is the same as for other methods. The "self" pointer in this case
664 should be the type of the method you are overriding so that you don't
665 get warnings during compilation. Also to call the method of the parent
666 class, you can use the PARENT_HANDLER macro with your arguments. Example:
669 override (Gtk:Container) void
670 add (Gtk:Container *self (check null type), Gtk:Widget *wid (check null type))
673 PARENT_HANDLER(self, wid);
677 If the function has a return value, then PARENT_HANDLER is an expression that
678 you can use. It will return whatever the parent handler returned, or the
679 "onerror" expression if there was no parent handler.
683 Inside the code, aliases are set for the methods, so that you don't
684 have to type the class name before each call, just the name of the method.
697 return foo(self) + i;
702 Underscore removal (0.93.5+):
704 Sometimes this causes conflicts with other libraries. For example a library
705 might have already used the identifier foo. You can prepend an underscore to
706 the name in the .gob file. This will make the local short alias have an
707 initial underscore, but it will not change the name of the actual name of the
708 function. For example:
710 class My:Object from Gtk:Object {
717 /* short calling convention */
719 /* long calling convention */
724 Thus you see that the "_foo" method still generates the method "my_object_foo"
725 just as "foo" would generate. You can turn off this behavior if you depend
726 on the old (pre 0.93.5) behavior with the --no-kill-underscores option. This
727 also means that if both "_foo" and "foo" are defined, it is treated as a
730 This does not apply to override methods. Override methods are special beasts
731 and this is not necessary and would make the code behave in weird ways.
735 You should define a new method which should be a normal public method. Inside
736 this method, you can use the GET_NEW macro that is defined for you and that
737 will fetch a new object, so a fairly standard new method would look like:
743 ret = GTK_OBJECT (GET_NEW);
751 There are some standard casts defined for you. Instead of using the full
752 macros inside the .c file, you can use SELF, IS_SELF and SELF_CLASS. Using
753 these makes it easier to for example change class names around.
757 Since 0.93.5, there have also been defined the Self and SelfClass types inside
758 your .c file. These serve the same function as the above, they make it easier
759 to type and easier to change typenames around which can help a lot during
760 prototyping stage. However you should note that the Self type should not be
761 used in function prototypes as one of the arguments or as a return value type.
762 This is because this is a simple C typedef which is only available inside you
763 .c file. You can disable both the self casting macros and the self type
764 aliases by passing --no-self-alias to
766 .SH DEALING WITH DIFFERENT GOB VERSIONS
770 In your generated C file, you can use the defines GOB_VERSION_MAJOR
771 GOB_VERSION_MINOR and GOB_VERSION_PATCHLEVEL if you wish to for example
772 use a feature that is only available in some newer gob version. Note however
773 that you can only use these defines in the C code portions of your .gob file,
774 and #ifdef's cannot span multiple functions. Check the BUGS section
775 for more on using the C preprocessor and gob. Also note that these
776 have only been available since the 0.92.1 version of gob.
778 Minimum version requires:
780 You can also make your .gob file require at least certain version of gob. You
781 do this by putting 'requires x.y.z' (where x.y.z is the version number) outside
782 of any C block, comment or class, usually you should make this the first line
783 in the file or close to the top. If gob finds this and the version of gob used
784 to compile the code is lower then that listed in the require, gob will generate
785 an error and exit. For example to require that gob version 0.92.1 or higher
786 be used to compile a file, put this at the top of that file:
792 It should be noted however that this feature was not added until 0.92.1, and
793 so if the file gets compiled by a lower version, gob would generate a
794 syntax error. Thus by putting in a requires line, you are implicitly
795 requiring at least 0.92.1.
799 There is a C++ mode so that gob creates C++ compiler friendly files. You need
800 to use the --for-cpp argument to gob. This will make the generated file have
801 a .cc instead of a .c extension, and several things will be adjusted to
802 make it all work for a C++ compiler. One thing that will be missing is an
803 alias to the new method, as that clashes with C++, so instead you'll have to
804 use the full name of the method inside your code. Also note that gob does
805 not use any C++ features, this option will just make the generated code
806 compile with a C++ compiler.
808 .SH IDENTIFIER CONFLICTS
810 Gob will need to define some local variables and functions in the generated
811 files, so you need to take some precaution not to conflict with these. The
812 general rule of thumb is that all of these start with three underscores. There
813 is one, "parent_class" which doesn't because it's intended for use in your
814 code. For virtuals or signals, you cannot use the identifier __parent__
815 which is used for the parent of the object. You should actually never access
816 __parent__ either as it not guaranteed that it will stay named this way.
817 Data members cannot be named __parent__ nor _priv. For methods, you cannot
818 use the identifiers "init" or "class_init" unless you mean the constructor
819 methods. You shouldn't generally use 3 underscores even in override method
820 argument lists and virtual and signal method names as it might confuse the
821 PARENT_HANDLER macro. In fact avoiding all names with three underscores is
822 the best policy when working with gob.
824 Also note that starting with version 0.93.5, method names that start with a
825 an underscore are equivalent to the names without the initial underscore. This
826 is done to avoid conflicts with the aliases. Thus you can define the method
827 as "_name", if "name" happens to be some standard library function. This is
828 the same as defining it as "name" except that the local alias will be "_name"
831 There are a couple of defines which you shouldn't be redefining in the code
832 or other headers. These are SELF, IS_SELF, SELF_CLASS, ARG, VAR,
833 PARENT_HANDLER, GET_NEW, GOB_VERSION_MAJOR, GOB_VERSION_MINOR and
834 GOB_VERSION_PATCHLEVEL.
836 As for types, there are Self and SelfClass types which are only defined in your
837 source files. Their generation (just like the generation of the SELF macros)
838 can be turned off, see command line options.
840 .SH USING GTK-DOC STYLE INLINE DOCUMENTATION
842 If you want to use gtk-doc style inline documentation for your objects, you
843 can do one of two things. First, you could include the inline documentation
844 comments in your %{ %} section which will then be put verbatim into the
845 output source file. This is the way you should use for functions you define
846 outside of the class.
848 For class methods, you should use a gtk+ style comment, however it can be
849 indented any number of tabs or spaces and you can use the short method name
850 without the type prefix. Gob will automatically try to extract these and
851 translate to full names and put them in the output source file. An example
855 class Gtk:Button:Example from Gtk:Button {
859 * Makes a new #GtkButtonExample widget
861 * Returns: a new widget
867 return GTK_WIDGET(GET_NEW);
872 If the function you are documenting is a signal or a virtual then it will
873 be documenting the wrapper that starts that virtual function or emits
876 .SH DEALING WITH CIRCULAR HEADERS
878 Sometimes you may need to use an object of type MyObjectA in the MyObjectB
879 class and vice versa. Obviously you can't include headers for both. So you
880 need to just declare the typedef in the header of A for B, and the other way
881 around as well. The headers generated since v0.92.2 include a protecting
882 define before it declares the typedef. This define is the
883 __TYPEDEF_<upper case object name>__. So inside my-object-a.h there will be
887 #ifndef __TYPEDEF_MY_OBJECT_A__
888 #define __TYPEDEF_MY_OBJECT_A__
889 typedef struct _MyObjectA MyObjectA;
893 Now instead of including my-object-a.h in the header section of
894 my-object-b.gob, just copy the above code there and you're set for using
895 MyObjectA as a type in the method parameters and public types.
897 Another way to get out of this problem is if you can use those types only
898 in the private members, in which case they won't be in the generated public
901 .SH BUILDING WITH MAKE
903 If you are using normal makefiles, what you need to do is to add a generic
904 rule for .gob files. So you would include the following in the Makefile
905 and then just use the .c and .h files as usual (make sure the space
906 before the 'gob' is a tab, not spaces):
909 %.c %.h %-private.h: %.gob
914 .SH BUILDING WITH AUTOCONF and AUTOMAKE
916 This is a little bit more involved. Basically the first thing to do is to
917 check for GOB in your configure.in file. You can use the supplied m4 macro
918 which will also check the version of gob. Basically you include this:
924 This will replace @GOB@ in your makefiles with the full path of gob. Thus
925 when adding the generic rule to your Makefile.am file, it should look like:
928 %.c %.h %-private.h: %.gob
933 For Makefile.am you have to set up a couple more things. First you have to
934 include the generated .c and .h files into BUILT_SOURCES variable. You
935 have to include both the .gob and the .c and .h files in the SOURCES for your
940 GOB does several things to make debugging the code easier. First it adds
941 preprocessor commands into the output c file that point to the correct places
942 in your .gob input file. However sometimes there might be some bigger
943 confusion and this is just not helpful. In this case you will probably want
944 to have gcc point you directly at the generated files. For this use
945 the --no-lines command line option. You should also note that these commands
946 are not generated for the public header file at all. If there is an error which
947 points you to the public header file, make sure you fix this error in the .gob
948 file, otherwise your changes will not have any effect after gob recompiles the
951 Sometimes you might want to know which method you are in for some debugging
952 output. GOB will define __GOB_FUNCTION__ macro, which is just a string constant
953 with a pretty name of the method.
957 The lexer does not actually parse the C code, so I'm sure that some corner
958 cases or maybe even some not so corner cases of C syntax might confuse gob
959 completely. If you find any, send me the source that makes it go gaga and I'll
960 try to make the lexer try to handle it properly, but no promises.
962 Another thing is that gob ignores preprocessor macros. Since gob counts
963 braces, the following code won't work:
975 To make this work, you'd have to do this:
988 There is no real good way we can handle this without parsing C code, so we
989 probably never will. In the future, I might add #if 0 as a comment but
990 that's about as far as I can really take it and even that is problematic.
991 Basically, if you use gob, just don't use the C preprocessor too extensively.
993 Comments will not get through to the generated files unless inside C code.
994 This makes using something like gtk-doc harder. However I'm planning to
997 The short name aliases are actually implemented as pointers to functions. Thus
998 if you want to get the pointer of a function using the short name alias you
999 can't use the '&'. Thus:
1002 void (*foo)(Self *);
1004 /* this will NOT work */
1007 /* this will work */
1010 /* Both of these will work */
1011 foo = &my_class_long_name;
1012 foo = my_class_long_name;
1018 George Lebl <jirka@5z.com>
projects / gob-dx.git / blob