PyMaemo/Accessing APIs without Python bindings - Revision history

213.150.1.132: /* Accessing Items in a GList */

213.150.1.132 — Sun, 12 Sep 2010 11:02:14 GMT

Accessing Items in a GList

← Older revision		Revision as of 11:02, 12 September 2010
Line 133:		Line 133:

	Once you are done with the <code>GList</code> manipulation, you should free its memory:		Once you are done with the <code>GList</code> manipulation, you should free its memory:
		+
		+	With some functions (NOT this one, see docs), you should also unref the list items first:
		+	<source lang="python">
		+	for i in glist(stuffs):
		+	gobject.g_object_unref(i)
		+	</source>
		+
		+	Then free the list itself:
	<source lang="python">		<source lang="python">
	glib.g_list_free(contacts)		glib.g_list_free(contacts)
	</source>		</source>
		+
	== Final Words ==		== Final Words ==

amigadave: use and


amigadave — Tue, 22 Jun 2010 12:10:14 GMT
use <source> and <code>
Show changes



frals: Undo revision 33973 --- unrelated link by spambot
frals — Tue, 25 May 2010 08:32:49 GMT
Undo revision 33973 --- unrelated link by spambot

		
		
		
		
		
		
		← Older revision
		Revision as of 08:32, 25 May 2010
		
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 This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.  This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.
-  
- ==Related Links:==  
-  
- [http://www.bodybuildingrevealed.com/'''body building''']  
  
 See also more usage examples [[/More examples|here]].  See also more usage examples [[/More examples|here]].
  
 [[Category:Python]]  [[Category:Python]]




203.177.74.138 at 00:29, 7 May 2010
203.177.74.138 — Fri, 07 May 2010 00:29:27 GMT


		
		
		
		
		
		
		← Older revision
		Revision as of 00:29, 7 May 2010
		
		Line 139:
Line 139:
  
 This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.  This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.
  + 
  + ==Related Links:==
  + 
  + [http://www.bodybuildingrevealed.com/'''body building''']
  
 See also more usage examples [[/More examples|here]].  See also more usage examples [[/More examples|here]].
  
 [[Category:Python]]  [[Category:Python]]




lizardo: /* Accessing Items in a GList */
lizardo — Mon, 12 Apr 2010 14:09:36 GMT
Accessing Items in a GList

		
		
		
		
		
		
		← Older revision
		Revision as of 14:09, 12 April 2010
		
		Line 113:
Line 113:
  
   glib = ctypes.CDLL('libglib-2.0.so.0')    glib = ctypes.CDLL('libglib-2.0.so.0')
-   
   def glist(addr):    def glist(addr):
-      size = glib.g_list_length(addr)  
       class _GList(ctypes.Structure):        class _GList(ctypes.Structure):
-           _fields_ = [('data', ctypes.c_void_p)] +           _fields_ = [('data', ctypes.c_void_p),
-      for i in xrange(0, size): +                      ('next', ctypes.c_void_p)]
-           item = glib.g_list_nth(addr, i) +      l = addr
-           yield _GList.from_address(item).data +      while l:
  +           l = _GList.from_address(l)
  +           yield l.data
  +          l = l.next
  
 This function uses the yield statement to construct a so called [http://docs.python.org/tutorial/classes.html#generators generator]. The actual GList manipulation is made using functions from libglib library. This generator makes it very easy to iterate over the items:  This function uses the yield statement to construct a so called [http://docs.python.org/tutorial/classes.html#generators generator]. The actual GList manipulation is made using functions from libglib library. This generator makes it very easy to iterate over the items:




lizardo: /* Final Words */
lizardo — Sat, 10 Apr 2010 18:02:20 GMT
Final Words

		
		
		
		
		
		
		← Older revision
		Revision as of 18:02, 10 April 2010
		
		Line 138:
Line 138:
  
 This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.  This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.
  + 
  + See also more usage examples [[/More examples|here]].
  
 [[Category:Python]]  [[Category:Python]]




lizardo: /* Calling a Function Which Returns a GObject (i.e. a Constructor) */
lizardo — Sat, 10 Apr 2010 17:34:51 GMT
Calling a Function Which Returns a GObject (i.e. a Constructor)

		
		
		
		
		
		
		← Older revision
		Revision as of 17:34, 10 April 2010
		
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 The byref() function returns a pointer to the given data. The hash() function returns the memory address of the argument.  The byref() function returns a pointer to the given data. The hash() function returns the memory address of the argument.
  
- == Calling a Function Which Returns a GObject (i.e. a Constructor) == + == Calling a Function Which Returns a GObject ==
  
 Every GObject instance created by a C library must have a corresponding Python object, so that it can be manipulated on Python code. This object, which acts like a "wrapper" around the C pointer, is created using the pygobject_new() C function. Unfortunately, pygobject_new() is not a plain function, but a macro which points to a function pointer in a struct (see /usr/include/pygtk-2.0/pygobject.h on the "#define pygobject_new ..." line), making it a little more complex to be called from Python. The snippet of code below, borrowed from [http://faq.pygtk.org/index.py?req=show&file=faq23.041.htp PyGTK FAQ], will take care of this:  Every GObject instance created by a C library must have a corresponding Python object, so that it can be manipulated on Python code. This object, which acts like a "wrapper" around the C pointer, is created using the pygobject_new() C function. Unfortunately, pygobject_new() is not a plain function, but a macro which points to a function pointer in a struct (see /usr/include/pygtk-2.0/pygobject.h on the "#define pygobject_new ..." line), making it a little more complex to be called from Python. The snippet of code below, borrowed from [http://faq.pygtk.org/index.py?req=show&file=faq23.041.htp PyGTK FAQ], will take care of this:




amigadave: Category:Python
amigadave — Thu, 11 Feb 2010 15:46:25 GMT
Category:Python

		
		
		
		
		
		
		← Older revision
		Revision as of 15:46, 11 February 2010
		
		Line 138:
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 This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.  This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.
  + 
  + [[Category:Python]]




lizardo: /* Calling a Function Which Returns a GObject (i.e. a Constructor) */
lizardo — Tue, 02 Feb 2010 13:14:33 GMT
Calling a Function Which Returns a GObject (i.e. a Constructor)

		
		
		
		
		
		
		← Older revision
		Revision as of 13:14, 2 February 2010
		
		Line 75:
Line 75:
   class PyGObjectCPAI(object):    class PyGObjectCPAI(object):
       def __init__(self):        def __init__(self):
  +          import gobject
           py_obj = ctypes.py_object(gobject._PyGObject_API)            py_obj = ctypes.py_object(gobject._PyGObject_API)
           addr = ctypes.pythonapi.PyCObject_AsVoidPtr(py_obj)            addr = ctypes.pythonapi.PyCObject_AsVoidPtr(py_obj)




lizardo: /* Initializing libosso-abook */
lizardo — Tue, 02 Feb 2010 13:14:11 GMT
Initializing libosso-abook

		
		
		
		
		
		
		← Older revision
		Revision as of 13:14, 2 February 2010
		
		Line 40:
Line 40:
  
   import sys    import sys
  +  import ctypes
  +  # be sure to import gtk before calling osso_abook_init()
  +  import gtk
         
   osso_abook = ctypes.CDLL('libosso-abook-1.0.so.0')    osso_abook = ctypes.CDLL('libosso-abook-1.0.so.0')

← Older revision		Revision as of 08:32, 25 May 2010
Line 139:		Line 139:

	This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.		This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.
-
-	~~==Related Links:==~~
-
-	~~[http://www.bodybuildingrevealed.com/'''body building''']~~

	See also more usage examples [[/More examples\|here]].		See also more usage examples [[/More examples\|here]].

	[[Category:Python]]		[[Category:Python]]

← Older revision		Revision as of 00:29, 7 May 2010
Line 139:		Line 139:

	This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.		This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.
		+
		+	==Related Links:==
		+
		+	[http://www.bodybuildingrevealed.com/'''body building''']

	See also more usage examples [[/More examples\|here]].		See also more usage examples [[/More examples\|here]].

	[[Category:Python]]		[[Category:Python]]

← Older revision		Revision as of 14:09, 12 April 2010
Line 113:		Line 113:

	glib = ctypes.CDLL('libglib-2.0.so.0')		glib = ctypes.CDLL('libglib-2.0.so.0')
-
	def glist(addr):		def glist(addr):
-	~~size = glib.g_list_length(addr)~~
	class _GList(ctypes.Structure):		class _GList(ctypes.Structure):
-	_fields_ = [('data', ctypes.c_void_p)]	+	_fields_ = [('data', ctypes.c_void_p),
-	~~for i in xrange~~(0, ~~size~~):	+	('next', ctypes.c_void_p)]
-	~~item~~ = ~~glib~~.~~g_list_nth~~(~~addr, i~~)	+	l = addr
-	yield ~~_GList.from_address(item)~~.data	+	while l:
		+	l = _GList.from_address(l)
		+	yield l.data
		+	l = l.next

	This function uses the yield statement to construct a so called [http://docs.python.org/tutorial/classes.html#generators generator]. The actual GList manipulation is made using functions from libglib library. This generator makes it very easy to iterate over the items:		This function uses the yield statement to construct a so called [http://docs.python.org/tutorial/classes.html#generators generator]. The actual GList manipulation is made using functions from libglib library. This generator makes it very easy to iterate over the items:

← Older revision		Revision as of 18:02, 10 April 2010
Line 138:		Line 138:

	This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.		This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.
		+
		+	See also more usage examples [[/More examples\|here]].

	[[Category:Python]]		[[Category:Python]]

← Older revision		Revision as of 17:34, 10 April 2010
Line 52:		Line 52:
	The byref() function returns a pointer to the given data. The hash() function returns the memory address of the argument.		The byref() function returns a pointer to the given data. The hash() function returns the memory address of the argument.

-	== Calling a Function Which Returns a GObject ~~(i.e. a Constructor)~~ ==	+	== Calling a Function Which Returns a GObject ==

	Every GObject instance created by a C library must have a corresponding Python object, so that it can be manipulated on Python code. This object, which acts like a "wrapper" around the C pointer, is created using the pygobject_new() C function. Unfortunately, pygobject_new() is not a plain function, but a macro which points to a function pointer in a struct (see /usr/include/pygtk-2.0/pygobject.h on the "#define pygobject_new ..." line), making it a little more complex to be called from Python. The snippet of code below, borrowed from [http://faq.pygtk.org/index.py?req=show&file=faq23.041.htp PyGTK FAQ], will take care of this:		Every GObject instance created by a C library must have a corresponding Python object, so that it can be manipulated on Python code. This object, which acts like a "wrapper" around the C pointer, is created using the pygobject_new() C function. Unfortunately, pygobject_new() is not a plain function, but a macro which points to a function pointer in a struct (see /usr/include/pygtk-2.0/pygobject.h on the "#define pygobject_new ..." line), making it a little more complex to be called from Python. The snippet of code below, borrowed from [http://faq.pygtk.org/index.py?req=show&file=faq23.041.htp PyGTK FAQ], will take care of this:

← Older revision		Revision as of 15:46, 11 February 2010
Line 138:		Line 138:

	This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.		This document purpose is to give a basic understanding necessary to use ctypes to explore C libraries, specially ones that manipulate GObject. Notably, we do not describe how to define callbacks, but this is left as an exercise for the reader. Again, be sure to read the [http://docs.python.org/library/ctypes.html#callback-functions ctypes documentation] if you are interested in more advanced techniques.
		+
		+	[[Category:Python]]

← Older revision		Revision as of 13:14, 2 February 2010
Line 75:		Line 75:
	class PyGObjectCPAI(object):		class PyGObjectCPAI(object):
	def __init__(self):		def __init__(self):
		+	import gobject
	py_obj = ctypes.py_object(gobject._PyGObject_API)		py_obj = ctypes.py_object(gobject._PyGObject_API)
	addr = ctypes.pythonapi.PyCObject_AsVoidPtr(py_obj)		addr = ctypes.pythonapi.PyCObject_AsVoidPtr(py_obj)

← Older revision		Revision as of 13:14, 2 February 2010
Line 40:		Line 40:

	import sys		import sys
		+	import ctypes
		+	# be sure to import gtk before calling osso_abook_init()
		+	import gtk

	osso_abook = ctypes.CDLL('libosso-abook-1.0.so.0')		osso_abook = ctypes.CDLL('libosso-abook-1.0.so.0')