New submission from Gregory P. Smith: The Py_SIZE() macro is not documented. It should be. It is very useful along with PyList_New(positive_number) after using PyList_SET_ITEM() to fill in up to the first positive_number elements of a list object in the most optimal manner by avoiding numerous redundant array resizes and error checks along the away. The Py_SIZE() macro was introduced (in 2.6 I believe) and is specifically intended for use as an lvalue (see http://bugs.python.org/issue1724 to confirm that). It currently has uses in several places in CPython's core and modules as well as within some third party extension modules and tools such as Cython). ---------- assignee: docs@python components: Documentation keywords: easy messages: 222633 nosy: docs@python, gregory.p.smith priority: normal severity: normal status: open title: Document the Py_SIZE() macro. type: performance versions: Python 2.7, Python 3.4, Python 3.5 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue21949> _______________________________________