Skip Montanaro wrote:
    les> suppose I am reading lines from a file or stdin.  I want to just
    les> "peek" in to the next line, and if it starts with a special
    les> character I want to break out of a for loop, other wise I want to
    les> do readline().

Create a wrapper around the file object:

[snip]

Of course, this could be tested (which my example hasn't been)

If you'd like something that works similarly and has been tested a bit, try one of my recipes for peeking into an iterator:


http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/304373

You also might consider writing an iterator wrapper for a file object:

>>> class strangefileiter(object):
...     def __init__(self, file):
...         self.itr = iter(file)
...     def __iter__(self):
...         while True:
...             next = self.itr.next()
...             if not next or next.rstrip('\n') == "|":
...                 break
...             yield next
...
>>> file('temp.txt', 'w').write("""\
... some text
... some more
... |
... not really text""")
>>> for line in strangefileiter(file('temp.txt')):
...     print repr(line)
...
'some text\n'
'some more\n'
>>> file('temp.txt', 'w').write("""\
... some text
... some more
...
... really text""")
>>> for line in strangefileiter(file('temp.txt')):
...     print repr(line)
...
'some text\n'
'some more\n'
'\n'
'really text'


Steve -- http://mail.python.org/mailman/listinfo/python-list

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