print doesn't respect file inheritance?

[Terry Reedy]

bukzor wrote:
> I was trying to change the behaviour of print (tee all output to a
> temp file) by inheriting from file and overwriting sys.stdout, but it
> looks like print uses C-level stuff  to do its writes which bypasses
> the python object/inhertiance system. It looks like I need to use
> composition instead of inheritance, but thought this was strange
> enough to note.
> 
> $python -V
> Python 2.5
> 
> """A short demo script"""
> class notafile(file):
>     def __init__(self, *args, **kwargs):
>         readonly = ['closed', '__class__', 'encoding', 'mode', 'name',
> 'newlines', 'softspace']
>         file.__init__(self, *args, **kwargs)
>         for attr in dir(file):
>             if attr in readonly: continue
>             setattr(self, attr, None)

Drop the __init__ and give notafile a .write method.
Composition version inheritance is not the the real issue.

 >>> class nf(object):
     def write(s):
         print(s)
         print(s)

 >>> print >>nf(), 'testing'
testing
testing

Now change nf.write to put the copy where you want it.

tjr