On Jul 16, 2008, at 4:43 PM, Tamas wrote:
> > Hi, > > I am not a professional coder; hobby-like thing. > I would like to encapsulate my table definitions in a new class: > > class MyTable( Table): > def __init__( self, metadata): > Table.__init__( self, my_table_name, metadata, col1, col2...) > > metadata = MetaData() > table = MyTable( metadata) > > Traceback (most recent call last): > File "create_tables.py", line 11, in <module> > table = MyTable( metadata) > TypeError: __call__() takes at least 3 arguments (2 given) > > ******* > I tested different things and I have the feeling that it is not > possible to subclass the Table class. > Is this true? > > If no: what is the mistake I make? > > If yes: why? does Table class have some special decoration or > something like that? > How do you avoid to define your table in every script you write to > use that table with its corresponding class? its possible, but tricky since the creation of a Table is routed through a metaclass which ensures that only one instance of Table for a particular name within the MetaData exists, i.e.: -> t1 = Table('t1', metadata, ...) -> t2 = Table('t1', metadata, ...) -> t1 is t2 True So true subclassing here would require that you also subclass the metaclass to do what you want here, which is probably not a good idea since thats not public API stuff. If its just a creational pattern you're looking for, I'd suggest using a def instead of a class: def MyTable(metadata): return Table('myname', metadata, ...) If there's other behavior you're looking for, let us know what it is and we'll see if we can accomodate you. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---