From: Brian Candler <B.Candler@...>
Date: 2004-10-10T02:06:45+09:00
Subject: Re: quality of error messages

On Sun, Oct 10, 2004 at 01:45:23AM +0900, Markus wrote:
>      Instead, try to capture what they DON'T do, and store the location
> to use in the message if there turns out to be a problem.  What don't
> they do?  
> 
>       * They don't 'exdent' beyond the indentation of the line that
>         started the present construct, except for comments & here docs,
>         etc. which are already distinguished by the compiler.

I think you're saying: warn (or note the location of) any line which has
fewer spaces at the front than the number of spaces which were in front of
the line which started the current (most deeply nested) construct.

That seems OK to me; you won't get warnings for
   def foo
   line1
        line2
     line3
     end

but we don't really care, as we're unlikely to have a missing 'end' here.

>       * They don't start a nested construct at the same indentation
>         level of the present construct.

I do :-( Especially for deeply-nested modules: to keep listings not too
deeply indented, I write

module Foo
module Bar
class C1
  def m1
  end
end # class C1
class C2
  def m2
  end
end # class C2
end # module Bar
end # module Foo

> I suspect that this would be dirt simple to implement, especially
> compared to anything that required lookahead.

You're probably right there. Good enough would do. After all, it's only a
hint when you get a 'syntax error' at the end of the file.

Since you've been playing with the parser anyway, perhaps you can have a
look at it? :-)

Brian.