[Tutor] dynamically creating files

[Daniel Ehrenberg]

--- bob wrote:
> I am creating a program and have come to a problem. 
> I wish to write a class that handles file objects,
> ie opening, writing to,
> and closing a file. I wish to dynamically create the
> file name, as each
> instance would have its own file too use for
> processing. I am not sure on
> what syntax is required to derive a filename from
> the 'self' instance. 
> Any tips/ TIA

I think what you want to do is subclass the file type.
Here's a simple subtype of the file class that has
input from one file and output to another class. It
will act similarly to a file in rU+ mode.

class newfile(file):
    def __init__(self, inputfile, outputfile):
        self.inputfile = file(inputfile, 'rU')
        self.outputfile = file(outputfile, 'w')
    def read(self, *args):
        return self.inputfile.read(*args)
    def write(self, *args):
        return self.outputfile.write(*args)

This code is untested and there may be errors in it.

Daniel Ehrenberg

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