Adding subclasses at runtime about classy_enum HOT 5 CLOSED

The problem with using anonymous classes (ie Class.new) is that there isn't any way to know the name of the class before it is created, and therefor the inherited hook doesn't have the information it needs to properly create the enum member. Have you considered just using eval to do it?

[0.13, 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30].each do |num|
  num_str = num.to_s.sub(/\./, '_')
  eval "ContaminantDepth::I#{num_str} < ContaminantDepth; end"
end

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Hmm, interesting. That makes sense, thanks.

I tried to avoid eval, since using a string interpolation for this sort of thing inherently seems ugly.

I'm pretty new to Ruby's meta-programming features; are you aware of any way I could do the equivalent to that eval, but using the cleaner block syntax, as I had done before?

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I'm not sure of a way to do it off hand, I would try Stack Overflow and see if anyone has a suggestion.

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So just FYI, the solution I went with was defining the class in an eval, and then using class_eval to nicely define the methods in a block.

Like so:

[0.13, 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30].each do |num|
    num_str = num.to_s.sub(/\./, '_')
    class_name = "In#{num_str}"

    # Must define the class non-anonymously, so superclass' 'inherited' hook gets class name
    eval "class ContaminantDepthIn::#{class_name} <  ContaminantDepthIn; end"

    ContaminantDepthIn.const_get(class_name).class_eval do
        define_method :value do
            num
        end
    end
end

Feels a little dirty, but it's better than just one long eval.

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Awesome, glad you were able to come up with something you're happy with!

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