bug with isinstance() ?
sjmachin at lexicon.net
Thu Jun 2 01:28:23 CEST 2005
> I guess the problem is I'm thinking of "classes"
> as these abstract concepts, sort of like Platonian "forms", whereas I
> should be thinking of classes as "class objects", object instances,
> each coming from some module's namespace... is this sort of the idea?
> Someone help me wrap my head around this, please. :)
Yes, you're getting it; Python is a dynamic language. Even classes can
be created on the fly.
I have a kit for reading/writing boring old legacy mainframe-style files
containg multiple record types with fixed-length fields. The record
definitions are stored as data, not as code. A skeleton class's source
is actually *local* to the class-making function. This means the class
statement is executed each time the function is called. The function
takes the current class instance like a shopping trolley and fills it up
with more methods and attributes, before parking it in a dictionary
keyed on the record name.
Taxpayer = file_dict['TXPYR']
taxpayer = Taxpayer()
taxpayer.name = 'John Q Doe'
taxpayer.date_of_birth = datetime.date(1970, 12, 31)
taxpayer.reportable_income = 1234.56
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