How to determine from which module a specific function was imported in elixir

问题

When multiple external modules are included by calling use on some intermediate module, is there an easy way to determine in which module given method is actually defined?

E.g:

defmodule ModuleB do
  def method_b do
  end
end    

defmodule ModuleA do
  # imports ModuleB implicitly
  use SomeModuleImportingModuleB

  def method_a
    # how to determine this is ModuleB.method_b?
    method_b
  end
end

回答1:

I found a solution that works for me, by capturing the function using & and then inspecting it:

def method_a
  IO.inspect &method_b/0 
  # outputs &ModuleB.method_b
  method_b
end

回答2:

Every module defines an __info__ function, you can use it to view functions exported by that module:

IO.inspect ModuleB.__info__(:exports)
# => [method_b: 0, module_info: 0, module_info: 1, __info__: 1]

Please note that when using use the module in question might be injecting code directly into the module being defined and creating functions dynamically - this might cause functions to become available that have not been defined in the used module.

来源：https://stackoverflow.com/questions/32648894/how-to-determine-from-which-module-a-specific-function-was-imported-in-elixir