Mailman 3 November 2012 - capi-sig

Getting doc strings into Py_ErrFormat
by Robert Steckroth 22 Nov '12

22 Nov '12

Is it possible to get a attribute doc/info string into a PyErr_Format(). I have the following error message and it seems like a good thing to print the help message for the align attribute. How would this be accomplished? Do any of you think this is foolish or a non-nonsensical? return PyErr_Format(PyExc_TypeError, "align=[%s] is not a valid option.", PyString_AsString(align)); -- Bust0ut, Surgemcgee: Systems Engineer --- surgemcgee.com Django_Teamplate3d

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Re: [capi-sig] Tips for developing application using python capi
by Francis Bolduc 21 Nov '12

21 Nov '12

The CPython API documentation is extensive, but it is geared towards very simple use-cases. When you do more advanced stuff, you're on your own. I usually end-up having to read the CPython code itself to find out what does what and how things work. Having a debugger to step in the code is essential. Following the call graph will give you more understanding than reading any documentation or examples. So, my tip is to build CPython yourself and get first-hand experience working with it's code. On Wed, Nov 21, 2012 at 2:00 PM, nirmoy das <nirmoy.aiemd(a)gmail.com> wrote: > Hey guys, > > I developing a application in c but i need python to support > Cassandra Database. I wrote Few API but felt bit complex while coding > python C-API. > Give some tips to for developing application using python capi. > _______________________________________________ > capi-sig mailing list > capi-sig(a)python.org > http://mail.python.org/mailman/listinfo/capi-sig -- Francis Bolduc, B.Sc. CM-Labs Simulation Inc.

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Tips for developing application using python capi
by nirmoy das 21 Nov '12

21 Nov '12

Hey guys, I developing a application in c but i need python to support Cassandra Database. I wrote Few API but felt bit complex while coding python C-API. Give some tips to for developing application using python capi.

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Re: [capi-sig] expression as argument of a object
by nirmoy das 21 Nov '12

21 Nov '12

can any one give a example .It gonna help me a lot On Wed, Nov 21, 2012 at 5:08 PM, nirmoy das <nirmoy.aiemd(a)gmail.com> wrote: > Can anyone tell me how to use expression in PyObject_CallObject() > as argument of object > > ex:column_family('keyspace', 'CF', comparator_type=comparator) > > >

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expression as argument of a object
by nirmoy das 21 Nov '12

21 Nov '12

Can anyone tell me how to use expression in PyObject_CallObject() as argument of object ex:column_family('keyspace', 'CF', comparator_type=comparator)

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Re: [capi-sig] Dynamically add members to a object at runtime
by M.-A. Lemburg 21 Nov '12

21 Nov '12

On 20.11.2012 16:23, Robert Steckroth wrote: > Hello Gang, I have come across the need to dynamically add members to an > object at runtime. I would like to attach many objects of a > single separate type into a object for processing. > Is there a way to dynamically create object members while maintaining the > (de)allocation structure? > It would be nice to create an array of objects in a single PyObject but > then a Py_DECREF() > would not work on all of the objects in the array. Has anyone > come across the need for this? It would make the module I am creating very > easy to use. If not, a short "no" will not hurt my feelings ,') > > > E.g. > w = DateTime() > x = DateTime() > my_object.add(w) > my_object.add(x) > > And then have some internal stuff possess those objects, E.g. > my_object.combine_dates() Dynamically adding members is possible, but requires extra work. I'd simply stick all the extra objects into a dictionary, have the object reference (and hold the reference to) the dictionary and release it when the object is deallocated. If you want garbage collection to work on your object, you will also have to implement the traversal API, so that cyclic references can be dealt with by the Python GC. -- Marc-Andre Lemburg eGenix.com Professional Python Services directly from the Source (#1, Nov 21 2012) >>> Python Projects, Consulting and Support ... http://www.egenix.com/ >>> mxODBC.Zope/Plone.Database.Adapter ... http://zope.egenix.com/ >>> mxODBC, mxDateTime, mxTextTools ... http://python.egenix.com/ ________________________________________________________________________ ::: Try our new mxODBC.Connect Python Database Interface for free ! :::: eGenix.com Software, Skills and Services GmbH Pastor-Loeh-Str.48 D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg Registered at Amtsgericht Duesseldorf: HRB 46611 http://www.egenix.com/company/contact/

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Re: [capi-sig] Dynamically add members to a object at runtime
by Campbell Barton 20 Nov '12

20 Nov '12

Internally you can use a list in your custom PyObject's struct, (or possibly a tuple if you are sure its kept for internal use - since you'd have to resize it). if you do hold a reference to other PyObject's from a PyTypeObject you define, be sure to fill in PyTypeObject.tp_traverse and include Py_TPFLAGS_HAVE_GC in your tp_flags. for example see: Another option is to attach a PyObject* dict to your struct and define PyTypeObject.tp_dictoffset for example see: https://svn.blender.org/svnroot/bf-blender/trunk/blender/source/blender/pyt… lines, 72, 156 This has the advantage you can add whatever you like into your object and name your members too, without messing with tp_traverse. On Wed, Nov 21, 2012 at 2:23 AM, Robert Steckroth <robertsteckroth(a)gmail.com> wrote: > Hello Gang, I have come across the need to dynamically add members to an > object at runtime. I would like to attach many objects of a > single separate type into a object for processing. > Is there a way to dynamically create object members while maintaining the > (de)allocation structure? > It would be nice to create an array of objects in a single PyObject but > then a Py_DECREF() > would not work on all of the objects in the array. Has anyone > come across the need for this? It would make the module I am creating very > easy to use. If not, a short "no" will not hurt my feelings ,') > > > E.g. > w = DateTime() > x = DateTime() > my_object.add(w) > my_object.add(x) > > And then have some internal stuff possess those objects, E.g. > my_object.combine_dates() > > > > -- > Bust0ut, Surgemcgee: Systems Engineer --- > surgemcgee.com > Django_Teamplate3d > _______________________________________________ > capi-sig mailing list > capi-sig(a)python.org > http://mail.python.org/mailman/listinfo/capi-sig -- - Campbell

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Dynamically add members to a object at runtime
by Robert Steckroth 20 Nov '12

20 Nov '12

Hello Gang, I have come across the need to dynamically add members to an object at runtime. I would like to attach many objects of a single separate type into a object for processing. Is there a way to dynamically create object members while maintaining the (de)allocation structure? It would be nice to create an array of objects in a single PyObject but then a Py_DECREF() would not work on all of the objects in the array. Has anyone come across the need for this? It would make the module I am creating very easy to use. If not, a short "no" will not hurt my feelings ,') E.g. w = DateTime() x = DateTime() my_object.add(w) my_object.add(x) And then have some internal stuff possess those objects, E.g. my_object.combine_dates() -- Bust0ut, Surgemcgee: Systems Engineer --- surgemcgee.com Django_Teamplate3d

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Re: [capi-sig] Keyword creation in a module function
by Stefan Behnel 09 Nov '12

09 Nov '12

Robert Steckroth, 09.11.2012 04:54: > Well, turns out that while the keyword dictionary thing is complex, my > problem was elsewhere. Have you considered using Cython? It would allow you to concentrate on the real problems, i.e. the functionality you want to implement, rather than having to dig into this kind of low-level issues. Stefan

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Re: [capi-sig] Keyword creation in a module function
by Robert Steckroth 09 Nov '12

09 Nov '12

Well, turns out that while the keyword dictionary thing is complex, my problem was elsewhere. Is it possible that the documentation is wrong? The capital "S" in the docs state this -> S (object) [PyObject *] Same as O. here http://docs.python.org/2/c-api/arg.html?highlight=keyword#Py_BuildValue But "S" it has string checking properties as opposed to "O". E.g. "if ( ! PyArg_ParseTupleAndKeywords(args, kwds, "|OSllS"... != "if ( ! PyArg_ParseTupleAndKeywords(args, kwds, "|OOllO"... Anyway, got my thing figured out :) On Thu, Nov 8, 2012 at 6:09 PM, Robert Steckroth <robertsteckroth(a)gmail.com>wrote: > Hey Gang, I have come across the need to pass both keywords and arguments > from one function to another. The keywords are passing just fine with a > PyObjectCall command. However, if the user does not specify any keywords at > the interpretor, the command will seg-fault. > The docs state that keywords argument can be NULL, but this does not work > with NULL set objects. > How do I build a keywords dictionary which can function correctly if there > are none to start with or if the user defined some? I am thinking it can > be done with a PyDict() like command? > > The below snippet is the scenario I am trying to achieve --> > > if ( kwds ) { > self->c_surface = PyObject_Call((PyObject *) &PyMyObject_Type, > object_args, kwds); } > else { self->c_surface = PyObject_Call((PyObject *) &PyMyObject_Type, > object_args, NULL); } > > > > > -- > Bust0ut, Surgemcgee: Systems Engineer --- > surgemcgee.com > Django_Teamplate3d > -- Bust0ut, Surgemcgee: Systems Engineer --- surgemcgee.com Django_Teamplate3d

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