GOB \- The GTK+ Object Builder
.SH SYNOPSIS
.PP
-.B gob
+.B gob [-?] [-h] [-w] [--exit-on-warn] [--no-exit-on-warn] [--for-cpp]
+[--no-touch-headers] file
.SH DESCRIPTION
.PP
GTK+ Object Builder is a simple preprocessor for easily creating
GTK+ objects. It does not parse any C code and ignores any C errors. It
is in spirit similar to things like lex or yacc.
+.SH OPTIONS
+.PP
+.TP
+.B -?
+.TP
+.B -h
+Display a simple help screen.
+.TP
+.B -w
+.TP
+.B --exit-on-warn
+Exit with an errorcode even when you encounter a warning.
+.TP
+.B --no-exit-on-warn
+Exit with an error only on errors, not on warnings, this is the default.
+.TP
+.B --for-cpp
+Generate C++ code.
+.TP
+.B --no-touch-headers
+Don't touch the generated header file unless it really changed, this avoids
+spurious rebuilds, but can confuse some make systems (automake in particular),
+so it is not enabled by default.
+
+
.SH TYPENAMES
.PP
-Because we need to parse out different parts of the typename,
-sometimes you need to specify the typename with some special syntax.
-Types are specified in capitalized form and words are separated by ':'.
-The first word of the type (which can be empty) is the "namespace". This
-fact is for example used for the type checking macro. For "Gtk:New:Button",
-the macro will be GTK_IS_NEW_BUTTON. This format of typenames is used in
-the class declaration header and for method argument types.
+Because we need to parse out different parts of the typename, sometimes you
+need to specify the typename with some special syntax. Types are specified in
+capitalized form and words are separated by ':'. The first word of the type
+(which can be empty) is the "namespace". This fact is for example used for the
+type checking macro and the type macro. For "Gtk:New:Button", the macros will
+be GTK_IS_NEW_BUTTON and GTK_TYPE_NEW_BUTTON. This colon separated format of
+typenames is used in the class declaration header and for method argument
+types.
-.SH OUTPUT FILE NAMES
+.SH OUTPUT FILES
.PP
The filenames are created from the typename. The words are
separated by '-' and all in lower case. For example for an object named
"Gtk:New:Button", the files are gtk-new-button.c and gtk-new-button.h.
+The header file is created to be human readable and to be used as a
+reference to the object. The .c source file is not created as a human
+readable source and is littered with #line statements, which make the
+compiler attempt to point you to the right line in your .gob file in
+case of parsing errors. The output should not be editted by hand, and
+you should only edit the .gob file.
.SH INCLUDING NORMAL C CODE IN THE OUTPUT FILES
.PP
-To include some code directly in the output C file begin with
-'%{' on an empty line and end the code with a '%{' on an empty line. To
+To include some code directly in the output C file begin with '%{'
+on an empty line and end the code with a '%}' on an empty line. To
put the code in the output header file, start the code with a '%h{'.
For example:
.nf
%h{
+ /* will be included in the header */
void somefunc(int i);
%}
+
%{
+ /* will be included in the C file */
void somefunc(int i)
{
- /* some code */
+ /* some code */
}
%}
.fi
+.SH INCLUDE FILES
+.PP
+Gob will automatically include the class header file at the top of the .c
+source file. If you wish to include it somewhere else, put the include
+into some %{ %} section above the class definition, and gob will not include
+it automatically. This way you can avoid circular includes and control
+where in the file do you want to include the header.
+
.SH MAKING A NEW CLASS
.PP
The class header:
.fi
.PP
-The private members are not currently protected from outside use,
-they are just marked by a comment in the header file, this will most likely
-be somehow solved in some future version.
+Public datamembers are accessed normally as members of the object struct.
+Example where 'i' is as above a public data member:
+.nf
+
+ object->i = 1;
+
+.fi
+.PP
+The private data members are defined in a structure which is only available
+inside the .c file. You must access them using the structure _priv. Example
+where 'h' is the private data member (as in the above example):
+.nf
+
+ object->_priv->h = NULL;
+
+.fi
+Note that the _priv structure is only accessible to C code blocks below or
+inside the class definition in the .gob file. If you use it above, you will
+get a 'dereferencing incomplete pointer type' error from the C compiler.
.PP
The third type is an argument type. It is a named datamember which
is one of the features of the GTK+ object system. You need to define a get
and a set handler. They are fragments of C code that will be used to
get the value or set the value of the argument. Inside them you can use the
define ARG to which you assign the data or get the data. You can also use
-the identifier "this" as pointer to the object instance. The type is
+the identifier "self" as pointer to the object instance. The type is
defined as one of the gtk type enums, but without the GTK_TYPE_ prefix.
For example:
.nf
public int height;
- argument INT height set { this->height = ARG; } get { ARG = this->height; };
+ argument INT height set { self->height = ARG; } get { ARG = self->height; };
.fi
.PP
.nf
public int height;
- argument (CONSTRUCT) INT height get { ARG = this->height; };
+ argument (CONSTRUCT) INT height get { ARG = self->height; };
.fi
.PP
Argument lists:
.PP
For all but the init and init_class methods, you use the
-following syntax for arguments. The first argument can be just "this",
+following syntax for arguments. The first argument can be just "self",
which gob will translate into a pointer to the object instance. The rest
of the arguments are very similar to normal C arguments. If the
typename is an object pointer you should use the syntax defined above
!= or ==. Example:
.nf
- public int foo(this, int h (check > 0 < 11), Gtk:Widget *w (check null type))
+ public int foo(self, int h (check > 0 < 11), Gtk:Widget *w (check null type))
.fi
.PP
-This will be the prototype of a function which has a this pointer
+This will be the prototype of a function which has a self pointer
as the first argument, an integer argument which will be checked and has
to be more then 0 and less then 11, and a pointer to a GtkWidget object
instance and it is checked for being null and the type will also be
output, they just delimit the string. For example
.nf
- public void * get_something(this, int i (check >= 0)) onerror NULL {
+ public void * get_something(self, int i (check >= 0)) onerror NULL {
...
}
which makes calling the methods he same as public methods. This type of
method is just a little bit "slower" then normal functions, but not as
slow as signals. You define them by using "virtual" keyword before the
-prototype.
+prototype. If you put the keyword "private" right after the "virtual"
+keyword, the wrapper will not be a public method, but a private one.
.PP
Signals:
.PP
first or last. You specify that by "first" or "last" right after the
"signal" keyword. Then you need to define the gtk enum types (again
without the GTK_TYPE_ prefix). For that you define the return types
-and the types of arguments after the "this" pointer (not including the
-"this" pointer). You put it in the following syntax "<return type> (<list
+and the types of arguments after the "self" pointer (not including the
+"self" pointer). You put it in the following syntax "<return type> (<list
of arguments>)". If the return type is void, the type should be "NONE",
the same should be for the argument list. The rest of the prototype is
the same as for other method types. The body can also be empty, and
.nf
signal first INT(POINTER,INT)
- int do_something(this, Gtk:Widget *w (check null type), int length)
+ int do_something(self, Gtk:Widget *w (check null type), int length)
{
...
}
or
- signal last NONE(NONE) void foo(this);
+ signal last NONE(NONE) void foo(self);
.fi
.PP
+If you don't want the wrapper that emits the signal to be public, you can
+include the keyword "private" after the "signal" keyword. This will make
+the wrapper a normal private method.
+.PP
+If you don't define a "first" or a "last", the default will be taken as
+"last".
+.PP
Override methods:
.PP
If you need to override some method (a signal or a virtual method
of some class in the parent tree of the new object), you can define and
override method. After the "override" keyword, you should put the
typename of the class you are overriding a method from. Other then that
-it is the same as for other methods. The "this" pointer in this case
+it is the same as for other methods. The "self" pointer in this case
should be the type of the method you are overriding so that you don't
-get warnings during compilation. Example:
+get warnings during compilation. Also to call the method of the parent
+class, you can use the PARENT_HANDLER macro with your arguments. Example:
.nf
override (Gtk:Container) void
- add (Gtk:Container *this (check null type), Gtk:Widget *wid (check null type))
+ add (Gtk:Container *self (check null type), Gtk:Widget *wid (check null type))
{
- ...
+ /* some code here */
+ PARENT_HANDLER(self, wid);
}
+
.fi
.PP
Calling methods:
.PP
-Inside the code, defines are set for the methods, so that you don't
-have to type the class name before each call. Example:
+Inside the code, pointers are set for the methods, so that you don't
+have to type the class name before each call, just the name of the method.
+Example:
.nf
private int
- foo(this)
+ foo(self)
{
- return this->len;
+ return self->len;
}
private int
- bar(this,int i)
+ bar(self,int i)
{
- return foo(this) + i;
+ return foo(self) + i;
}
.fi
will fetch a new object, so a fairly standard new method would look like:
.nf
- public GtkWidget *
+ public GtkObject *
new(void) {
GtkObject *ret;
ret = GTK_OBJECT (GET_NEW);
.fi
+.SH C++ MODE
+.PP
+There is a C++ mode so that gob creates C++ compiler friendly files. You need
+to use the --for-cpp argument to gob. This will make the generated file have
+a .cc instead of a .c extention, and several things will be adjusted to
+make it all work for a C++ compiler. One thing that will be missing is an
+alias to the new method, as that clashes with C++, so instead you'll have to
+use the full name of the method inside your code. Also note that gob does
+not use any C++ features, this option will just make the generated code
+compile with a C++ compiler.
+
.SH BUGS
.PP
-The generated header file is included as the first file in the .c file, no
-matter what. This means that you will have to put things that need to be included
-before that, into an %h{ } section.
+Also the lexer does not actually parse the C code, so I'm sure that some corner
+cases or maybe even some not so corner cases of C syntax might confuse gob
+completely. If you find any, send me the source that makes it go gaga and I'll
+try to make the lexer try to handle it properly, but no promises.
+.PP
+Another thing is that gob ignores preprocessor macros. Since gob counts
+braces, the following code won't work:
+.nf
+
+ #ifdef SOME_DEFINE
+ if(foo) {
+ #else
+ if(bar) {
+ #endif
+ blah();
+ }
+
+.fi
+To make this work, you'd have to do this:
+.nf
+
+ #ifdef SOME_DEFINE
+ if(foo)
+ #else
+ if(bar)
+ #endif
+ {
+ blah();
+ }
+
+.fi
+There is no real good way we can handle this without parsing C code, so we
+probably never will. In the future, I might add #if 0 as a comment but
+that's about as far as I can really take it and even that is problematic.
+Basically, if you use gob, just don't use the C preprocessor too extensively.
.SH AUTHOR
.PP
projects / gob-dx.git / blobdiff