Hi all!
I'm trying to extend the functionality of the file object by creating a class that derives from file. MyFile class re-implements __init__(), write(), writelines() and close() to augment the capabilities of file.
All works fine, except for one thing: 'print >> myfile' does not execute Myfile.write(), it executes the file.write(). If I execute myfile.write() explicitly, then Myfile.write() is called as expected.
I was not expecting that behaviour. I though that 'print >> afileobject ' would execute the afileobject.write() as you can easily obtain by defining a simple file-like class that implements write() and writeline().
I am running Python 2.3.4. Can't move to 2.4 yet.
Is it the expected behavior?
# M y F i l e -- Testing inheritance from file --
# ^^^^^^^^^^^
#
class MyFile(file):
""" Testing new-style class inheritance from file""" #
def __init__(self, name, mode="r", buffering=-1, verbose=False):
"""Constructor"""self.was_modified = False
self.verbose = verbose
super(MyFile, self).__init__(name, mode, buffering)
if self.verbose:
print "MyFile %s is opened. The mode is: %s" % (self.name, self.mode)
#
def write(self, a_string):
""" Write a string to the file.""" super(MyFile, self).write(a_string)
self.was_modified = True #
def writelines(self, sequence):
""" Write a sequence of strings to the file. """ super(MyFile, self).writelines(sequence)
self.was_modified = True #
def close(self) :
"""Close the file.""" if self.verbose:
print "Closing file %s" % self.name super(MyFile, self).close()
self.was_modified = False
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