Nested macros, comments, and macro variable lookup

[bew]

https://carc.in/#/r/1zai

{% for verb in {:get, :post, :put} %}
  macro {{verb.id}}(arg)
    puts "not commented" \{{arg}}
    # puts "commented" \{{arg}}          # => undefined macro variable 'arg'
  end
{% end %}

The escaped macro variable lookup isn't respected when the line is commented.

[bew]

Now that I re-think about it, whether the line is commented or not doesn't make sense for macro code, but all I wanted was to comment a line in the macro, just to check something.

I think there is currently no way to comment stuff in a macro without breaking like in OP.

As we already have {% %} for macro statement, {{ }} for printed macro statement, we could have {# #} for commenting stuff in macros?

Maybe it's not a good idea to allow multiline commenting, as this could be abused to comment multiple lines in normal code, we could have {#} to comment to the end of the line?

[bew]

I just realized I can comment macro stuff with:

{% # comment
 %}

# or (cleaner?)

{%
 # comment
 %}

# note: this doesn't work, as the %} is understood as part of the comment
{% # comment %}

I would still prefer a dedicated syntax like {#} as it would be easier to use, but it's good enough for now.

Or maybe we can change the behevior for {% # comment %} to ensure that the %} is not understood as part of the comment? (but there might be tricky edge cases with this method)

[jwoertink]

I just ran in to this using 1.4.1

class Base
  macro inherited
    macro foo(name)
      # some comments \{{ name.id }}
      def foo
        puts "\{{ name.id }}"
      end
    end
  end
end
 
class Foo < Base
  foo bar
end

Foo.new.foo

Showing last frame. Use --error-trace for full trace.

error in line 4
Error: undefined macro variable 'name'

To get around this, it looks like you can use verbatim

class Base
  macro inherited
    {% verbatim do %}
      macro foo(name)
        # some comments {{name}}
        def foo
          puts "{{name.id}}"
        end
      end
    {% end %}
  end
end
 
class Foo < Base
  foo bar
end
 
Foo.new.foo

[asterite]

It's actually simpler: the \{{...}} doesn't seem to be working inside comments. Here's a very small example:

macro foo(name)
  # some comments \{{name.id}}
  "\{{name.id}}"

  {% debug %}
end

foo(hello)

The output is:

# some comments \hello
"{{name.id}}"

but it should be:

# some comments {{name.id}}
"{{name.id}}"