Method_added macro without method parameter

Help & Support
1

Hi everyone, macro newbie here.

I was trying to use the method_added macro (as mentioned in the guides) but I kept running into an issue. I don’t seem to get the method name as a parameter in the macro call. Example:

class Example < ExampleBase
  def example_method
    # Whatever logic happens here
  end
end

abstract class ExampleBase
  macro inherited
    macro method_added(method)
      {% puts "Method added:", method.name.stringify %}
    end
  end
end

I would expect to get example_method as parameter but instead I get Error: undefined macro variable 'method'

I can’t seem to access the method names even with the following example:

abstract class ExampleBase
  macro inherited
    {% puts @type.methods %}
  end
end

All I see is an empty array in the console (no methods available?).

I also attempted to wrap the call with finished but didn’t get the subclass methods either (still empty arrays) with this:

abstract class ExampleBase
  macro inherited
    macro finished
      {% puts @type.methods %}
    end
  end
end

Does this mean I can’t access those subclass method names within the inherited macro hook? Did I overlook something (i.e. only works for modules and not classes) or is there another way to access these methods from the subclass on a macro hook?

FYI tested this with version 1.7.3

2

The main cause is that the macro expression evaluates in the scope of macro inherited. To move it to expand later in macro method_added (or macro finished), you can escape it:

abstract class ExampleBase
  macro inherited
    macro method_added(method)
      \{% puts "Method added:", method.name.stringify %}
    end
  end
end

This should give you the expected behaviour, I presume.

2 Likes
3

This did the trick. Thank you @straight-shoota