Let method_missing also generate a def #3610

asterite · 2016-11-30T13:35:55Z

With this, the code generated by method_missing can also be a def, so one can control whether it captures a block, the block type, uses forall, etc. Example like this one:

class Bla
  def add(method, &block : -> U) forall U
    puts "added #{method} #{block}"
  end

  macro method_missing(call)
    def {{call.name}}(&block : -> U) forall U
      add({{call.name.stringify}}, &block)
    end
  end
end

bla = Bla.new

bla.some1 { 1 }
bla.some2 { 2 }

Output:

added some1 #<Proc(Int32):0x1063173a0>
added some2 #<Proc(Int32):0x1063173b0>

kostya · 2016-11-30T14:57:43Z

this is little strange because this is generate def and no call for it, it called by default?

asterite · 2016-11-30T16:00:31Z

The way method_missing works (and this is how it always worked) is that, when triggered (method not found), the body of method_missing is expanded and then a method that matches that call is created and added to the object. In that way only a few expansions are needed. For example:

# This will trigger method_missing, a `some_method` will be generated and added
foo.some_method

# Now the method already exists in the object, and it's also typed, so it's fast.
# No need to re-expand method_missing and to type check again
foo.some_method
foo.some_method
foo.some_method

So this PR makes it a bit more clear that what is actually going on is that method_missing generated a method, it's not a call replacement.

I'll add all of this to the docs. In any case I'll need to update them after this is merged :-)

Let method_missing also generate a def

2326cf2

asterite mentioned this pull request Nov 30, 2016

using block with method_missing #3602

Closed

asterite added topic:compiler kind:feature labels Dec 1, 2016

asterite added this to the 0.20.1 milestone Dec 1, 2016

asterite merged commit 6b098eb into master Dec 1, 2016

asterite deleted the feature/method_missing_def branch December 13, 2016 13:53

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Let method_missing also generate a def #3610

Let method_missing also generate a def #3610

asterite commented Nov 30, 2016

kostya commented Nov 30, 2016

asterite commented Nov 30, 2016

Let method_missing also generate a def #3610

Let method_missing also generate a def #3610

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asterite commented Nov 30, 2016

kostya commented Nov 30, 2016

asterite commented Nov 30, 2016