YAS to the "Reading line-by-line" Problem

[Jesse D. Sightler]

Ack is raising an exception for a normally occuring event really a
_good_ idea?  Generally exceptions are only used for things that
actually are error conditions, and it would seem to me that using them
as nothing more than a fancy flow-control construct is a sure path to
nasty spaghetti code.

I really do not like this idea.  :)

Moshe Zadka wrote:
> 
> (YAS == Yet Another Solution)
> 
> This solution introduces file-like objects which do the Right Thing(TM) at
> EOF: raise EOFError (instead of returning an empty string)
> 
> ----------------- cut here ------------------
> class File:
>         '''\
>         File-like objects which throw EOFError on End-of-File.
> 
>         Initialize with a file-like object.
>         '''
>         def __init__(self, file):
>                 self.__file=file
> 
>         def __getattr__(self, name):
>                 if name[:4]!='read':
>                         return getattr(self.__file, name)
>                 return _Wrap(getattr(self.__file, name))
> 
> class _Wrap:
>         def __init__(self, function):
>                 self.function=function
> 
>         def __call__(self, *args, **kw):
>                 ret=apply(self.function, args, kw)
>                 if ret=='': raise EOFError, 'no more data in file'
>                 return ret
> 
> def open(file, mode='r'):
>         '''\
>         return a file like object open to /file/ with mode /mode/,
>         which throws an EOFError on EOF
>         '''
>         import __builtin__
>         return File(__builtin__.open(file, mode))
> 
> def _test():
>         import sys
>         file=open('/etc/passwd')
>         try:
>                 while 1:
>                         sys.stdout.write(file.readline())
>         except EOFError: pass
> 
> if __name__=='__main__':
>         _test()
> ---------------------------- cut here ---------------------------
> 
> --
> Moshe Zadka <mzadka at geocities.com>.
> #!/usr/bin/tail -1
> Just another tail hacker.

-- 
---------------
Jesse D. Sightler
http://www3.pair.com/jsight/

"Do not use a hatchet to remove a fly from your friend's forehead." 
      - Chinese Proverb