OOP Question - adding methods to core classes

I'm talking to Ruby via XMLRPC using the XMLRPC package from SqS.

The library has this heinous case statement:
        val caseOf: {
                [True] -> [^ self wrapVal: '1' type: 'boolean'].
                [true] -> [^ self wrapVal: '1' type: 'boolean'].
                [False] -> [^ self wrapVal: '0' type: 'boolean'].
                [false] -> [^ self wrapVal: '0' type: 'boolean'].
        } otherwise: [
                (val class) caseOf: {
                        [SmallInteger] -> [^ self wrapVal: val asString type: 'i4'].
                        [Float] -> [^ self wrapVal: val asString type: 'double'].
                        [String] -> [^ self
                                wrapVal: (self normalize: val)].
                        [ByteString] -> [^ self
                                wrapVal: (self normalize: val)].
                        [XMLRPCDateTime] -> [^ self wrapVal: val encodeISO8601 type: 'dateTime.iso8601'].
                        [Array] -> [^ self
                                wrapVal: (self encodeArray: val)
                                type: 'array'].
                        [Dictionary] -> [^ self
                                wrapVal: (self encodeStruct: val)
                                type: 'struct'].
                } otherwise: [
                        val isStream
                                ifTrue: [^ self wrapVal: (Base64MimeConverter mimeEncode: val) contents type: 'base64']
                                ifFalse:
                                        "Unhandled type."
                                        [XMLRPCException signal: 'Unhandled type:  ' , val className].
                        ]]

I was thinking how beautiful this code could be if each class had it's own encode method, like:
    In method protocol *xmlrpc
        Symbol>>encodeForXmlRpc
        String>>encodeForXmlRpc
        etc.

BONUS: if this was the case, extending for new types would be ridiculously trivial - just add the method to the type instead of trying to hook into large control structures, e.g.
* so that a Symbol on the ST end is recognized as a Symbol on the Ruby side (ends up as a string right now)
*so that I can talk to remote Ruby objects

OTOH, I was concerned about cluttering the core classes.  I've been going back and forth with this kind of thing since I came to Smalltalk, never got it resolved.

What do you think?

Thanks.
Sean

On Sat, 30 Oct 2010, Sean P. DeNigris wrote:

snip

I agree with you. :) Core classes won't be cluttered, because you'll add
only 1-2 methods to a separate method category. Btw XML-RPC is so simple
that it could be reimplemented in an hour.


Levente
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Ralph Johnson wrote

Yes, this is the Smalltalk way.

Thanks.  It was actually a lot of fun to chop away large sections of the method.

Ralph Johnson wrote

When you add a method to existing classes, you want to try to avoid name
clashes.  Pick a name that nobody else is likely to use.   encodeForXmlRpc
is a good name for that reason.

Yeah, I went down that little path, where I kept the "encode" name and then thought, "hmm... not a good name for a method on a core class"

Sean