Am 10.09.2010 11:23, schrieb Albert-Jan Roskam:
Hi,
I've made a small data entry program where a picture of a hand-written,
scanned form is shown next to several text entries. The design has been
largely 'bottom up', although of course I started with a rough sketch. I
started with the following classes: Menu (responsible for the widget
creation), Autocomplete (a subclass of the tkinter text entry widget
which I've found on the internet, I wanted to keep this intact), Convert
(responsible for the conversion/cropping of the images, which is
somewhat tedious) and Events (here's the pain spot: this has become a
mixed bag). Originally, the Events class was supposed to contain all the
commands behind the widgets, but it has slowly gotten more
responsibilities. Notably, all methods that deal with reading/writing
the data also live here. The program is about 500 lines of code now,
including blanks.
It's difficult to judge from the outside. It sounds to me like a good
idea to create separate classes or modules for reading and writing.
I'd like to rewrite to entire program so that (1) all classes have just
one responsibility (2) classes connect to as little other classes (so it
becomes easy to e.g. change to another widget set). I'd love to hear
some thoughts or advice on the new design from you (I hope my
description wasn't too short). Is there a specific design pattern that
could be used?
One specific, additional question: the program has a title bar that
shows something like "processing file X (1 of 3; 33%)". My colleague
suggested to use the Iterator pattern (gang of four) for this. Is this
(a) overkill (b) a simple opportunity to apply this pattern?
For what exactly do you want to use the pattern?
The iterator pattern is easy to implement in Python. And the usage of
iterators is even more easy (you can use them in loops without calling
the next() method explicitly). Lists among others are iterator types.
You can create your own with generator functions or of course implement
the iterator-protocol. See here:
http://docs.python.org/library/stdtypes.html#iterator-types
Generally iterator types and generators are great features of Python.
For a more concrete advice you'd need to explain a bit further what you
need to do.
HTH
Jan
_______________________________________________
Tutor maillist - Tutor@python.org
To unsubscribe or change subscription options:
http://mail.python.org/mailman/listinfo/tutor
