Did I miss a smiley?
Returning a string makes no sense at all given the OP.
And that new meme of senselessly adding #copy to every literal string is a bad one. Stop it.
- Bert -
On Mar 2, 2007, at 15:23 , Ron Teitelbaum wrote:
codeThatMeansSomething ^'16r1F' copy
Is better!
Ron
From: David Mitchell
Another alternative is to create a class with a bunch of methods that represent the constants. The methods are simple:
codeThatMeansSomething ^'16r1F'
The neat thing is that it is dynamic and all the rules of late binding and message lookup come into play, you can build object structures with proxies, decorators, composites, and so on.
I actually did this on a large system (for money). It started out as a bunch of tables and we ended up with 3 instances that had rather insane interfaces (thousands of methods*). We thought it would be really slow, but it turned out to be measurably faster than dictionary lookups. Even better, we had revision history for our "dictionaries" because it was all methods.
- Oh, wait, I forgot I was in Squeak. Thousands of methods is no
big deal.
Bert Freudenberg wrote:
On Feb 27, 2007, at 10:08 , Mispunt wrote:
Hi all,
For programming my Lego Mindstorms NXT I have to use codes like 16r1F. But I actually want to be able to use "readable" codes. In a language like Java I will do that with a static const, but as far as I know I have to do it with symbols in Smalltalk.
No, there is a better way.
If you are inside one class (or its subclasses), you would use "class variables", one per constant. You add them in the class template:
Object subclass: #Bla instanceVariableNames: '' classVariableNames: 'Const1 Const2' poolDictionaries: '' category: 'Bert-Bla'
and the initialization code is in a class-side #initialize method:
initialize "self initialize" Const1 := 16r1F. Const2 := 12345.
You need to execute the "self initialize" in the browser to do the initialization. It will be executed automatically when loaded into another image.
Class variables are capitalized because they are sort-of "global", they can be used in the defining class, its metaclass, and all their subclasses. If you need to give access to these variables across the class hierarchies, then you would do the same, but as a subclass of SharedPool:
SharedPool subclass: #BlaConstants instanceVariableNames: '' classVariableNames: 'Const1 Const2' poolDictionaries: '' category: 'Bert-Bla'.
To use this "pool" of variables in another class, list it as a "pool dictionary":
Object subclass: #Bla instanceVariableNames: '' classVariableNames: '' poolDictionaries: 'BlaConstants' category: 'Bert-Bla'
This makes all class variables of BlaConstants available to Bla as if they were class variables.
There are quite a few other ways to allow "global" variables in Smalltalk, but this one is the "clean" way to do it which works nicely with tools like Monticello.
- Bert -