[IronPython] Named Tuple and IronPython 2

[Dino Viehland]

Not too long ago I prototyped a frames implementation including making _getframe work - but it doesn't include locals in the frames.  I guess in this case it would work just fine.

The downside is it results in a 50% perf degrade on Pybench when calling recursive functions.   But we're already really fast calling functions so maybe that's acceptable.  Anyway it's something we can consider for a post-2.0 release (maybe w/ a command line option to control its presence) but I came up with the prototype too late to go adding it to 2.0.

-----Original Message-----
From: users-bounces at lists.ironpython.com [mailto:users-bounces at lists.ironpython.com] On Behalf Of Michael Foord
Sent: Friday, September 19, 2008 5:27 AM
To: Discussion of IronPython
Subject: [IronPython] Named Tuple and IronPython 2

Hello all,

At PyCon UK Raymond Hettinger showed off the Named Tuple; a very useful recipe for creating tuples with named fields. It is becoming part of the standard library in Python 2.6.

http://code.activestate.com/recipes/500261/

 >>> from namedtuple import namedtuple
 >>> thing = namedtuple('thing', ('whizz', 'pop'))  >>> thing <class '__builtin__.thing'>  >>> i = thing(1, 2)  >>> i.whizz
1
 >>> i.pop
2
 >>> w, p = i
 >>> w, p
(1, 2)
 >>> i
thing(whizz=1, pop=2)
 >>>

I've attached a modified version that works with IronPython 2 B5 (it doesn't work with 2B4 due to a very odd bug that is now fixed).

The only change needed was to comment out the use of 'sys._getframe'
which is there for pickle support.

It is only conditionally used, because Jython didn't support this either
- but on Jython _getframe wasn't defined at all so the conditional check fails on IronPython:

    # Bypass this step in enviroments where
    # sys._getframe is not defined (Jython for example).
    if hasattr(_sys, '_getframe'):
        result.__module__ = _sys._getframe(1).f_globals['__name__']

I'll suggest a modification to the recipe that works with IronPython. A better solution would be to implement '_getframe' of course... :-)

Michael Foord

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