By using bind_quoted you are giving up control about when exactly the parameter gets expanded. In most cases you can ignore this fact, but sometimes expanding has side effects which you dont want to have.
defmodule Foo do
defmacro unless(cond, [do: branch, else: other_branch]) do
quote bind_quoted: [cond: cond, branch: branch, other_branch: other_branch] do
if cond, do: other_branch, else: branch
end
end
end
require Foo
Foo.unless true do
IO.puts "Branch"
else
IO.puts "Other Branch"
end
This will probably not do what you want (perhaps there is even refinement necessary, since I have blindly typed without beeing able to do a testrun). This has already been discussed about 8 weeks ago in another thread and might give you some insights as well:
