Re: Data access from multiple code modules

simon.hibbs@xxxxxxxxx wrote:
Jeremy Jones wrote:


What does main.py do? Are you creating an instance of the gui thingy?
If so, you could just pass DataObject into your gui thingy either into
the constructor or to a setter once you create an instance of it.


It's a wxPython app. I created the GUI initialy using wxGlade which
gave me a small myapp.py script, a file containing the main application
frame (containing a listbook controll) and several files containing
panel classes. Each panel class contains controlls for performing
various operations on the data set (adding records, deleting them,
running various transformations).

Do you mean the code effectively doing these operations is in the gui ?
If yes, it would be better to factor it out IMHO.

I can't say I understand how it all
works at a deep level,
although I've been hacking it about quite
successfuly so far.

Presumably if I pass DataObject through to the Frame object, and from
there through to the Panel objects then presumably this will solve the
probelm?

Presumably !-)

I guess it would be passed by reference so all the panels
would be working on the same data object?

Python doesn't really have a "pass by value" semantic, since "variables"
are really just names bound to (ie : refering to) objects. So when it
comes to arguments passing, the argument *name* is local to the function
(rebinding the name won't affect the binding in the caller's namespace),
but what's bound to the name is really a reference to the object (so
mutating the object will effectively affect it).

Doh! How simple. Why didn't I think of that? I'm too used to procedural
scripts where you'd just put everything in a global data structure. I
know this is bad,

Well, depends on the size of the script. But it sure doesn't scale !-)

And FWIW, even with procedural, it's possible (and usually better) to
pass arguments around instead of having a big global datastructure.
Classes are handy when many functions needs to share state (work on a
same dataset), but there's no way to have one call the other and pass it
the dataset.

but it's hard to get out of that mentality.

Seems you're on the right way !-)

--
bruno desthuilliers
python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in 'onurb@xxxxxxxxxxx'.split('@')])"
.

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