[Newbies] Check wheater an instance of a class is actually there or not

Randal L. Schwartz merlyn at stonehenge.com
Wed Dec 23 02:15:11 UTC 2009

>>>>> "Hans" == Hans Gruber <rukin at web.de> writes:

Hans> Now to my question:

Hans> How may I check wheater an instance of a class (in my case MyFileLibrary) has been created and exists at the time I check it.

Hans> (MyFileLibrary = nil) is always false.

Hans> I need this, because wenn an Instance of MyFileLibrary exists at the
Hans> checking time, I want to proceed with an other method than I want to
Hans> proceed with when an instance of MyFileLibrary does not exists.

Sounds like you want the singleton pattern.

The easiest way to do that is to not create instances at all,
and just dump all of your methods class side, and all of your "instance"
variables as "class instance" variables.

Then treat MyFileLibrary as if it is the only instance that ever exists,
and has a global name.

If that's not what you want, explain more.

Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<merlyn at stonehenge.com> <URL:http://www.stonehenge.com/merlyn/>
Smalltalk/Perl/Unix consulting, Technical writing, Comedy, etc. etc.
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