When you index an iterable the __index__ method is used, so Sage integers
will work in many contexts.
On Tuesday, 14 May 2013 12:06:35 UTC-7, John H Palmieri wrote:
>
> Why does Python handle Sage Integers well in some cases but not in others?
> For example:
>
> $ sage --python
> Python 2.7.4 (default, May 8 2013, 16:25:06)
> [GCC 4.7.3] on darwin
> Type "help", "copyright", "credits" or "license" for more information.
> >>> from sage.all import Integer
> >>> L = range(5)
> >>> L[Integer(2)] # works!
> 2
>
> >>> import re
> >>> matches = re.match("(?:foo)?(bar)?(sws)?", "foobarsws")
> >>> matches.group(0)
> 'foobarsws'
> >>> matches.group(Integer(0)) # doesn't work!
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> IndexError: no such group
>
> What would we need to do to make matches.group(Integer(0)) work? Note that
> when using Sage, rather than Python, if you evaluate "matches.group(0)", it
> gets preparsed to "matches.group(Integer(0))". I forget to use "int(0)" as
> the argument, and then I get annoyed by the "no such group" error. (See
> http://ask.sagemath.org/question/1520/python-thing-that-doesnt-work-in-sage-works-infor
> a similar question.)
>
> --
> John
>
>
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