Re: Getting the current line number

John Reppy wrote:

> No, but you might be able to run your sml code through the C preprocessor
> to get that information.  I don't know it any SML implementation provides
> this feature, but it might be a useful thing to standardize on (also
> __FILE__).

	Ah, __FILE__ would be good too, but I hadn't even thought about that 
yet.  I'm working on an interpreter/compiler, and I was thinking it 
might be useful to fill the line/file fields of syntatic structures 
created by the program with the program line and file that created them.

> After thinking about it a bit more, I realized that the following hack
> would work.  First, define the following helper function
> 
> fun file_line ex = let
>       val [s] = SMLofNJ.exnHistory ex
>       val (f, r) = Substring.splitl (fn #":" => false | _ => true) 
> (Substring.full s)
>       val ln = Substring.takel (fn #"." => false | _ => true) 
> (Substring.triml 1 r)
>       in
>         {file = Substring.string f, line = Substring.string ln}
>       end;
> 
> then you can get the file and line info at a given source code location
> by embedding the following code:
> 
> file_line ((raise Fail "") handle ex => ex);

	That's quite clever :-)  But admittedly too heavyweight for my current 
needs, but perhaps I'll use this in a later pass.  Thanks!




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