Hi,
I’ve written the following to debug function calls, not sure if it’s useful for anyone else, and if so should I put it somewhere?
iex(1)> require Debug; import Debug
Debug
iex(2)> inspect_call(round(2.3*4.5))
round(10.35) -> 10
iex(3)> inspect_call(inspect({:foo, 1+2}))
inspect({:foo, 3}) -> "{:foo, 3}"
"{:foo, 3}"
iex(4)> inspect_call(IO.inspect(1) + IO.inspect(2))
1
2
+(1, 2) -> 3
3
It’s hopefully a fairly easily understandable piece of macro, though only evaluating the arguments once did make it more complicated. The first pattern-matching is taken from the Macro.decompose_call/1 function.
defmodule Debug do
defmacro inspect_call(block) do
{name, args, rebuild} =
case block do
{:{}, _metadata_a, args} when is_list(args) ->
raise CompileError,
description: "Using inspect_call on a map literal is not supported",
file: __CALLER__.file,
line: __CALLER__.line
{{:., metadata_a, [remote, function]}, metadata_b, args}
when is_tuple(remote) or is_atom(remote) ->
{
Macro.to_string({{:., metadata_a, [remote, function]}, [no_parens: true], []}),
args,
fn new_args -> {{:., metadata_a, [remote, function]}, metadata_b, new_args} end
}
{name, metadata_a, args} when is_atom(name) and is_atom(args) ->
{to_string(name), [], fn _new_args -> {name, metadata_a, args} end}
{name, metadata_a, args} when is_atom(name) and is_list(args) ->
{to_string(name), args, fn new_args -> {name, metadata_a, new_args} end}
_ ->
raise CompileError,
description:
"Cannot understand function call #{Macro.to_string(block)}",
file: __CALLER__.file,
line: __CALLER__.line
end
eval_args =
for n <- 1..length(args) do
Macro.unique_var(:"eval_arg_#{n}", __MODULE__)
end
return_value = Macro.unique_var(:return_value, __MODULE__)
quote do
unquote_splicing(
for {e_a, a} <- Enum.zip(eval_args, args) do
quote do
unquote(e_a) = unquote(a)
end
end
)
IO.write(
unquote(name) <>
"(" <>
(unquote(eval_args)
|> Enum.map(&inspect/1)
|> Enum.join(", ")) <>
")"
)
unquote(return_value) = unquote(rebuild.(eval_args))
IO.puts(" -> " <> inspect(unquote(return_value)))
unquote(return_value)
end
end
end
