Simon wrote:
Okay I will fix my code and include "self" and see what happens. I
know I tried that before and got another error which I suspect was
another newbie error.
The idea behind the init_Pre is that I can put custom code here to
customize the __init__ instead of creating a new subclass. This kind
of hook pattern allows you to flatten your inheritance hierarchy. I
can choose in the init_Pre method to execute code before the init_exec
(which contains the default __init__ code) and still execute the
init_Exec method or I can completely customize the entire __init__ by
returning False from init_Pre and prevent the init_Exec from being
called. I use this type of pattern with almost all my methods. In
this way I can create a less complicated inheritance chain but still
have have custom code when needed without sub-classing.
I am use to Visual FoxPro which where you can do
=is.init_Pre().And.This.init_Exec() and the result is discarded so
that is why it looks the way it does. In this form init_Exec has to
return a value. However, If self.init_Pre(): self.init_Exec() would
work the same and then I could avoid returning a value.
Thanks,
Simon
On Aug 1, 5:52 am, Dave Angel <da...@ieee.org> wrote:
Nat Williams wrote:
As MRAB described, ALL instance methods need to accept 'self' as a first
parameter, as that will be passed to them implicitly when they are called.
This includes __init__. The name 'self' is just a commonly accepted
convention for the name of the instance object passed to methods. You don't
have to call it that, but you really should.
Take a look athttp://docs.python.org/tutorial/classes.html#class-objects
It might help shed some light on how methods and instances work.
One other thing. I'm a little confused by the first line of
dcObject.__init__:
self.init_Pre() and self.init_Exec()
I suspect this does not do what you think it does. init_Pre and init_Exec
will both be called by this expression (unless init_Pre throws an exception,
of course). You're not getting anything here that you wouldn't by just
calling each method on a separate line, except just making it harder to
read.
Read the doc-string for init_Pre() and for init_Exec(). The final
version of init_Pre() will return False in some circumstances, and in
those circumstances Simon doesn't want init_Exec() to be called. He's
deliberately using the short-circuit evaluation of 'and' to accomplish
that.
On Fri, Jul 31, 2009 at 8:53 PM, Simon <dciphercomput...@gmail.com> wrote:
Hi
So should the dcObject class include the "self" as well since I have
not defined an __init__ method in dcCursor?
Simon
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Every one of those methods in both of those classes need a "self" first
argument. As others have said, all instance methods need a 'self.'
(Please don't top-post. You should put new responses at the end of
quoted text, or sometimes inline if that's clearer.)
I don't understand your comparison to Foxpro. read on.
As your code was last posted, you don't need a return value from
init_Exec() Every function that doesn't have an explicit return will
return None. And None is interpreted as False in an "and" expression.
If you had an "if" around the whole thing, then you'd care.
DaveA
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