Python C API Question.

[Adonis]

This is my first crack at using Python from a C level, and also a long time
since I have even used C, so my wording might be off, when creating a new
list utilizing the PyList_New(...) function, instead of creating a list of a
fixed length, is there a way to create a variabled length instead?

Any help is greatly apprecited.

Adonis

 

[Diez B. Roggisch]

This is my first crack at using Python from a C level, and also a long
time since I have even used C, so my wording might be off, when creating a
new list utilizing the PyList_New(...) function, instead of creating a
list of a fixed length, is there a way to create a variabled length
instead?

AFAIK they are always variable length - they always support appending to
them. The argument is just about the initial capacity, so if you know that
beforehand, you can optimize allocation of list entries.

 

[Jeff Epler]

Please see
http://docs.python.org/api/listObjects.html

C's PyList_Append() is roughly equivalent to Python's list.append().
If you want to construct a list without knowing how many items will
eventually be in it, use PyList_New(0), then PyList_Append for each
item you want to add. This will be as efficient as the similar
Python code
l = [f(x) for x in s]
in terms of the number of resizes the internal array-of-pointers
undergoes.

Jeff

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