En Tue, 15 May 2007 20:38:14 -0300, MisterPete <[EMAIL PROTECTED]>
escribió:
> I could make wrappers around all of the file methods but that kind
> of defeats the purpose of inheriting from file. It's kind of odd to
> inherit from file but then keep a file object (although then it would
> at least pass any isinstance(object, file) tests at least) and
> overwrite every single method. I'd prefer that I inherit from file
> and just get flush and next and everything for free (and any new
> methods if they were added).
Instead of inheriting from file, you can delegate to a file instance.
Python makes it rather easy:
py> import sys
py>
py> class Output:
... file = None
... verbosity = 1
... def __init__(self, file=None, verbosity=1):
... if file is None: file = sys.stdout
... self.file = file
... self.verbosity = verbosity
... def write(self, string, messageVerbosity=1):
... if messageVerbosity <= self.verbosity:
... self.file.write(string)
... def __getattr__(self, name):
... return getattr(self.file, name)
... def __setattr__(self, name, value):
... if name in dir(self): self.__dict__[name] = value
... else: setattr(self.file, name, value)
...
py> f1 = Output(verbosity=100)
py> f1.write("Console output\n")
Console output
py> f1.flush()
py> print f1.isatty()
True
py> print f1.verbosity
100
py> f1.verbosity = 5
py> print f1.verbosity
5
py>
py> f2 = Output(open("aaa.txt","w"))
py> f2.write("Goes to another file\n")
py> f2.flush()
py> print f2.isatty()
False
py> print f2.tell()
22
py> f2.close()
As you can see, I'm using file methods and attributes that I didn't
redefine explicitely. See the section "Customizing attribute access" on
the Python Reference Manual about __getattr__ and __setattr__
--
Gabriel Genellina
--
http://mail.python.org/mailman/listinfo/python-list
