How can I add methods to a class at runtime in Smalltalk?

Question

I\'m building a Smalltalk API to an XML-based web service. The XML service is so regular that, rather than write the methods by hand, I figured I\'d just override #doe

Answer 1

If you just want the source string to more clearly reflect the method:

SomeObject>>addHello: name
  | methodTemplate methodSource |
  methodTemplate := 'sayHello{1}Times: count
  count timesRepeat: [ Transcript show: ''Hi, {1}!'' ].'.   
  methodSource := methodTemplate format: { name }.
  self class compile: methodSource.

If you want the source to be syntax-checked, you could start with a template method like this:

sayHelloTemplate: count
    count timesRepeat: [ Transcript show: 'Hi, NAME' ].

And then fill the template accordingly, like:

addHello2: name
    | methodTemplate methodSource |
    methodTemplate := (self class compiledMethodAt: #sayHelloTemplate:) decompileWithTemps.
    methodTemplate selector: ('sayHello', name, 'Times:') asSymbol.
    methodSource := methodTemplate sourceText copyReplaceAll: 'NAME' with: name.
    self class compile: methodSource.

Of course, all of this would be clearer if some methods were extracted :)