[Python-Dev] file(file) (original) (raw)

Georg Brandl g.brandl at gmx.net
Sat Jan 13 14:25:09 CET 2007

Terry Reedy schrieb:

| > We should also consider the semantics in more detail. Should the seek | > position be shared between the two objects? What about buffering? | | That's definitely the hard part. But it's somewhat similar to | "normal" mutable objects which are (I think always, right?) shallow | copied when used in a constructor.

But why, in the normal case, do you want a copy? It seems to me that is thefile is a file rather than a string, then that is what you want, and you are asking for 'thefile = file(thefile)' to work just as the iter statement does.

Consider the use case presented before:

def foo(thefile): if type(thefile) == str: thefile = open(thefile)

Now, if thefile is already a file object, you won't have to close it because it came from somewhere else. If thefile is a string, you'll have to close it at the end.

Now, if file(fileobject) would return another file object created by something like os.dup(), you can do

def foo(thefile): try: thefile = file(thefile)

     (...)
 finally:
     thefile.close()

Georg

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