Professional IronPython

Missing CPython Libraries
 
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The maximum recursion limit is unlimited in IronPython by default. You can call
sys.setrecursionlimit()
to set an appropriate value. As an alternative to coding the 
recursion change, you can use the 
–X:MaxRecursion 1000
command line switch to give 
IronPython behavior similar to that of CPython.
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IronPython tends to be more lenient about the use of keyword arguments in many cases. For 
example, IronPython will accept 
[].append.__call__(item=’abc’)
as usable code, but 
CPython will raise an error. In fact, IronPython is less restrictive in a number of ways. The 
following code raises an error in CPython but works fine in IronPython.
x = ‘’
x.center(1, fillchar=’*‘)
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The address returned by the 
socket.socket()
method differs between IronPython and 
CPython. Given an address of 0.0.0.0, IronPython returns 0.0.0.0 and CPython returns 0.
There are many other differences between IronPython and CPython that you can read about at 
http://ironpython.codeplex.com/wikipage?title=Differences
. Make sure you check the dif-
ferences for each IronPython version because the Web site doesn’t relist differences. In addition, some 
of the difference entries aren’t complete. The version 2.0.x page at 
http://ironpython.codeplex 
.com/wikipage?title=IPy2.0.xCPyDifferences&referringTitle=Differences
is an example.
mISSINg cPyTHoN lIBrArIES
IronPython isn’t a full implementation of CPython. Yes, it has most of the pieces, but some pieces are 
missing. A few of these pieces are written in C. IronPython relies heavily on pure Python modules, 
so the C modules don’t appear in IronPython unless someone has written an alternative for them. 
In some cases, the IronPython team simply hasn’t written the required module yet, but will in the 
future. Table A-1 provides a list of the missing CPython libraries and what they do for you.
The IronPython team is constantly adding new functionality to IronPython. 
This section lists the missing CPython libraries at the time of this writing (using 
IronPython version 2.6.10920.0), but the IronPython team will add at least 
some of these modules in the future.