[Python-Dev] Re: tarfile module (update)

Gustavo Niemeyer niemeyer@conectiva.com
Wed, 27 Nov 2002 10:17:12 -0200

> using factory functions to create objects representing external
> entities is an extremely common pattern.
> in the Pythobn library, this pattern is used in aifc, anydbm, audiodev,
> dbhash, dumbdbm (and all other dbm modules), fileinput, gettext,
> gopherlib, gzip, imghdr, optparse, popen2, shelve, sndhdr, socket,
> sunau, sunaudio, tempfile, tokenize,  just to name a few.

Perhaps I haven't explained it right. I was trying to tell that using a
default constructor would be more obvious than having a methodclass
"constructor" TarFile.open() which will be used 99.9% of the time.

I don't see this pattern in any of the modules you mention above.

> to figure out *why* it's a good idea to use a factory function, think
> as a user.  or as a library maintainer.

That helped a lot. Thank you.

Gustavo Niemeyer

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