On Mon, Oct 6, 2008 at 2:48 PM, Mark Volkmann <mark@ociweb.com> wrote:

On Oct 5, 2008, at 8:38 PM, Michael van der Gulik wrote:

What are you using enums for? I've never found I've needed them, often because the need for them can be refactored away and you end up with cleaner code.

Often I just use symbols (i.e. #red, #blue, #green). These are generic descriptive names for thingies.

I haven't used them yet in Smalltalk, but I'm thinking I'll have a need to verify that a value passed to a method is a member of a confined set. Maybe I should just test a symbol passed as an argument to a method to see if it's in an array of allowed symbols.

Well, there are simpler ways of doing that such as:

isMemberOfConfinedSet: anArg
    (ValidValues includes: anArg) ifFalse: [self error: 'foo'].
    ...

Where ValidValues is a class variable and a Collection of valid values.

Alternatively, a more Smalltalkish way that I don't like:

isMemberOfConfinedSet: anArg
    (anArg isSomething) ifFalse: [self error: 'foo'].

Where >>isSomething is implemented to return true on all objects that could be a member. This method I find rather intrusive, especially if implemented on core classes like Object and String, but does run very fast because a simple method that just returns true has special optimisations in the VM.

Gulik.

--
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