2013/3/7 Stefan Behnel <stefan...@behnel.de> > Yury V. Zaytsev, 07.03.2013 12:16: > > Is there any syntax that I can use to do something like this in Cython: > > > > py_object_ = PyList_New(123); ? > > Note that Python has an algorithm for shrinking a list on appending, so > this might not be sufficient for your use case. > > > > If not, do you think that this can be added in one way or another? > > > > Unfortunately, I can't think of a non-disruptive way of doing it. For > > instance, if this > > > > [None] * N > > > > is given a completely new meaning, like make an empty list (of NULLs), > > instead of making a real list of Nones, it will certainly break Python > > code. Besides, it would probably be still faster than no pre-allocation, > > but slower than an empty list with pre-allocation... > > > > Maybe > > > > [NULL] * N ? > > What do you need it for? > > Won't list comprehensions work for you? They could potentially be adapted > to presize the list. > > I guess the problem is to construct new (even empty) list with pre-allocated memory exactly for N elements.
N*[NULL] - changes semantics because there can't be list with N elements and filled by NULL. N*[None] - more expansive for further assignments because of Py_DECREFs. I suppose that N*[] could do the trick. It could be optimized so that N*[] is equal to an empty list but with preallocated memory exactly for N elements. Could it be? Zaur Shibzukhov
_______________________________________________ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
