Comments on: Infinitely nested lists in Python http://asmeurersympy.wordpress.com/2012/09/19/infinitely-nested-lists-in-python/ My blog on my work on SymPy and other fun stuff. Sat, 11 May 2013 17:46:45 +0000 hourly 1 http://wordpress.com/ By: Aaron Meurer http://asmeurersympy.wordpress.com/2012/09/19/infinitely-nested-lists-in-python/#comment-669 Wed, 19 Sep 2012 14:53:29 +0000 http://asmeurersympy.wordpress.com/?p=1160#comment-669 Nice. Before it segfaults, it prints a bunch of (. And it seems that it has been fixed in Python 3 (print(a) gives the same thing as repr(a)).

]]> By: Bradley Froehle http://asmeurersympy.wordpress.com/2012/09/19/infinitely-nested-lists-in-python/#comment-667 Wed, 19 Sep 2012 05:38:08 +0000 http://asmeurersympy.wordpress.com/?p=1160#comment-667 You can certainly do it for tuples using the CPython API. For example:

from ctypes import pythonapi, c_void_p, c_ssize_t, c_int
from _ctypes import PyObj_FromPtr

pythonapi.PyTuple_New.argtypes = (c_ssize_t,)
pythonapi.PyTuple_New.restype = c_void_p
pythonapi.PyTuple_SetItem.argtypes = (c_void_p, c_ssize_t, c_void_p)
pythonapi.PyTuple_SetItem.restype = c_int

a = pythonapi.PyTuple_New(1)
pythonapi.PyTuple_SetItem(a, 0, a)
a = PyObj_FromPtr(a)

assert type(a) is tuple
assert a[0] is a

repr(a) # ‘((…),)’
print(a) # segfault

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