[ python-Bugs-1476356 ] StringIO should implement __str__()

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Bugs item #1476356, was opened at 2006-04-25 15:11
Message generated for change (Comment added) made by rhettinger
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Category: Python Library
Group: None
>Status: Closed
>Resolution: Invalid
Priority: 5
Submitted By: Dom Lachowicz (cinamod)
Assigned to: Nobody/Anonymous (nobody)
Summary: StringIO should implement __str__()

Initial Comment:
I was a bit surprised when I discovered that StringIO
didn't have a __str__() method, equivalent to
getvalue(). Calling str(stringio_object) gives the
following:

>>> import StringIO
>>> s = StringIO.StringIO("hello world")
>>> print "%s" % (str(s))
<StringIO.StringIO instance at 0x401ef08c>

I had some (perhaps dodgy code) code that did:

if isinstance(data, types.FileType):
  return data.read()
else:
  return str(data)

Since StringIO doesn't subclass any file type and
doesn't implement a __str__() method, I was getting
seemingly bogus results. This was trivially worked
around by adding another "isinstance(data,
StringIO.StringIO)" case, but it was surprising
nonetheless. Thanks.

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>Comment By: Raymond Hettinger (rhettinger)
Date: 2006-04-25 17:58

Message:
Logged In: YES 
user_id=80475

This isn't a bug.  The module is correctly emulating the API
for file objects.

I recommend replacing your isintance() test with a try/except:

try:
.... return data.read()
except AttributeError:
.... return str(data)



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