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Merged
whatyouhide merged 2 commits into from
Apr 27, 2017
Merged

Validate the value of the @on_load attribute #6038

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8bcb1f2
Validate the value of the @on_load attribute
whatyouhide Apr 26, 2017
391e1a8
{atom, 0} as well
whatyouhide Apr 27, 2017
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20 changes: 15 additions & 5 deletions lib/elixir/lib/module.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -164,9 +164,11 @@ defmodule Module do

A hook that will be invoked whenever the module is loaded.

Accepts the function name (as an atom) of a function in the current module.
The function must have arity 0 (no arguments) and has to return `:ok`, otherwise
the loading of the module will be aborted. For example:
Accepts the function name (as an atom) of a function in the current module or
`{function_name, 0}` tuple where `function_name` is the name of a function in
the current module. The function must have arity 0 (no arguments) and has to
return `:ok`, otherwise the loading of the module will be aborted. For
example:

defmodule MyModule do
@on_load :load_check
Expand Down Expand Up @@ -1190,8 +1192,16 @@ defmodule Module do
end
end

defp preprocess_attribute(:on_load, atom) when is_atom(atom) do
{atom, 0}
defp preprocess_attribute(:on_load, value) do
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@josevalim josevalim Apr 27, 2017

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The @on_load attribute can be either {:fun, 0} or :fun. So I think we should probably leave this clause intact and add a clause that check when it is not in the tuple format above.

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@whatyouhide whatyouhide Apr 27, 2017

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Oh missed that, that's right. We don't document it in the docs for Module though, should we?

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@josevalim josevalim Apr 27, 2017

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We should, yes.

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@whatyouhide whatyouhide Apr 27, 2017

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Got it, updated. I didn't follow your suggestion but went with a single clause where we validate the value, similar to what we do for other attributes. Let me know if you prefer your suggestion and I'll change it :)

case value do
atom when is_atom(atom) ->
{atom, 0}
{atom, 0} = tuple when is_atom(atom) ->
tuple
other ->
raise ArgumentError, "expected the @on_load attribute to be an atom or a " <>
"{atom, 0} tuple, got: #{inspect(value)}"
end
end

defp preprocess_attribute(:behaviour, atom) when is_atom(atom) do
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9 changes: 9 additions & 0 deletions lib/elixir/test/elixir/kernel/errors_test.exs
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Expand Up @@ -572,6 +572,15 @@ defmodule Kernel.ErrorsTest do
end
end

test "@on_load attribute format" do
message = "expected the @on_load attribute to be an atom or a {atom, 0} tuple, got: \"not an atom\""
assert_raise ArgumentError, message, fn ->
defmodule BadOnLoadAttribute do
Module.put_attribute(__MODULE__, :on_load, "not an atom")
end
end
end

test "interpolation error" do
assert_compile_fail SyntaxError,
"nofile:1: \"do\" is missing terminator \"end\". unexpected token: \")\" at line 1",
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