[issue6616] PyList_APPEND (append without incref)
Raymond Hettinger rhettin...@users.sourceforge.net added the comment: I know the API well enough (with manipulating dicts/lists etc) and I still want this function for the sake of convenience. Given that your level of skill is higher than the average user, I recommend adding this to your own standard libraries or headers. No need to muck-up the environment for everyone else. -- assignee: - rhettinger resolution: - rejected status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue6616 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue6616] PyList_APPEND (append without incref)
New submission from Campbell Barton ideasma...@gmail.com: This patch was made on python r74276 Often when writing in C/Python I want to append to a list within a C loop of an unknown length. When this is done for newly created PyObject (which is quite common) - you need to assign each item to a variable and then decref it. eg: PyObject *item= PyFloat_FromDouble(x); PyList_Append(list, item); Py_DECREF(item); I have seen people make mistakes with this (in pygame code and blender3d), and run PyList_Append(list, PyFloat_FromDouble(x)), ofcourse this is not the fault of python/c api that devs do not read docs properly but I think it would be very convenient to have an append that works in a similar way to PyList_SET_ITEM This simple patch allows... PyList_APPEND(list, PyFloat_FromDouble(x)) doc included. -- files: py3_APPEND.diff keywords: patch messages: 91167 nosy: ideasman42 severity: normal status: open title: PyList_APPEND (append without incref) versions: Python 3.2 Added file: http://bugs.python.org/file14619/py3_APPEND.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue6616 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue6616] PyList_APPEND (append without incref)
Raymond Hettinger rhettin...@users.sourceforge.net added the comment: This simple patch allows... PyList_APPEND(list, PyFloat_FromDouble(x)) This isn't a good idea because the error checking for the inner function is lost. The current API encourages keeping one function per line so that the ref counting and error-checking are more obvious. Also, I'm not too keen on adding second-ways-to-do-it. The C API is already somewhat fat, making it harder to learn and remember. The current API has standard patterns of creating and consuming references. Introducing variants that don't follow those patterns makes it harder to review code and determine that it is correct. It is better to learn to use the API as designed than to commingle two different styles. -- nosy: +rhettinger ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue6616 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue6616] PyList_APPEND (append without incref)
Campbell Barton ideasma...@gmail.com added the comment: Hi Raymond, in general I agree with your comments that adding 2 ways to do things is not great. The reason I still think this is an advantage is that I know the API well enough (with manipulating dicts/lists etc) and I still want this function for the sake of convenience. For the same reason that PyList_SET_ITEM is useful, this is useful too. Loosing the error checking is a disadvantage but in many cases API's dont do error checking for every new item allocated. Python's own code does this in a few cases with PyList_SET_ITEM... eg. ./Python/_warnings.c:857: PyList_SET_ITEM(filters, 1, create_filter(PyExc_ImportWarning, ignore)) ./Python/Python-ast.c:2757: PyList_SET_ITEM(value, i, ast2obj_cmpop((cmpop_ty)asdl_seq_GET(o-v.Compare.ops, i))); -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue6616 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
