P
Pierre Rouleau
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
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