Module can even not exists at the compile time:
defmodule Foo do
def setup(funcs) do
Code.compile_quoted(quote bind_quoted: [funcs: funcs] do
defmodule RuntimeLookup do
for {name, value} <- funcs, do: def unquote(name)(), do: unquote(value)
end
end)
end
def main do
setup(foo: 42)
IO.inspect RuntimeLookup.foo()
end
end
This pattern was used in OTP <21.2 when there was no persistent_term functionality, and nowadays it is still used from time to time when you need high performance calls, ex. OpenCensus can be configured to use such construct for speeding up metrics dispatch.
