module Crystal::Repl::Multidispatch

Overview

Non-interpreted Crystal does multidispatch by essentially inlining is_a? calls and performing the appropriate casting and calling.

For the interpreter this is a bit hard to do because it's a stack-based VM, so it's hard to get access to stack values that are not at the top of the stack.

So, for interpreted mode, when there's a dispatch, we actually create a method that will do the dispatch, and we call that method. For example, if we have this code:

def foo(x : Int32)
end

def foo(x : Char)
end

a = 1 || 'a'
foo(a)

The call to foo is actually delegated to another foo method that will do the dispatch, created in this file:

def foo(x)
  if x.is_a?(Int32)
    foo(x)
  elsif x.is_a?(Char)
    foo(x)
  else
    unreachable
  end
end

Defined in:

compiler/crystal/interpreter/multidispatch.cr

Class Method Summary

• .create_def(context : Context, node : Call, target_defs : Array(Def))

Class Method Detail