http://d.puremagic.com/issues/show_bug.cgi?id=2660

           Summary: Change #line to pragma(line)
           Product: D
           Version: unspecified
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: clugdbug@yahoo.com.au


The #line special token sequence looks extremely foreign in the language.
Changing #line Integer FileSpec EndOfLine into:
pragma(line, Integer, FileSpec)
would free up the # character.


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http://d.puremagic.com/issues/show_bug.cgi?id=2660





------- Comment #1 from shro8822@vandals.uidaho.edu  2009-02-13 11:47 -------

I rather expect that will never happen as the #line bit is there for compatibility with the c preprocessed tool stack (lex, yacc, CPP and any other pre existing tools/editrs that need to remap line numbers)

In short, don't reinvent the wheel.


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http://d.puremagic.com/issues/show_bug.cgi?id=2660





------- Comment #2 from ary@esperanto.org.ar  2009-02-13 12:07 -------
But the #line is processed by the lexer, I don't see what that has to do with lex, yacc and other CPP tools...

The problem with the pragma solution is that pragmas are processed during the semantic pass, and line numbers are already assigned by then.

But I woudldn't mind the lexer peeking some tokens after "pragma" to see if it's "pragma(line" to make this happen. Some "magic" in benefit of making a programmer's life easy and making a character available for the language is worth it.

The same goes for my idea to make version(D1), version(D2) be processed in the lexical stage (to skip pieces of code so that you don't have to do the mixin workaround). The only excuses for not doing this seems to be that it will make the lexer a little harder for 3rd party tools to do. But: 1. most of the tools, if not all of them, use DMD's front end, and 2. it's very easy compared to other stuff that needs to be performed by a regular D compiler (mixins, templates, etc.).


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http://d.puremagic.com/issues/show_bug.cgi?id=2660





------- Comment #3 from shro8822@vandals.uidaho.edu  2009-02-13 13:30 -------
Take a look at what Lex/Yacc/Flex/Bison and a pile of other tools generate. Anything that is copied from the input file into the output is prefaced with #line so that errors point to the right place. I see no reason to break with this convention as I rather suspect that there are other tools out there that also leverage it.


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http://d.puremagic.com/issues/show_bug.cgi?id=2660





------- Comment #4 from clugdbug@yahoo.com.au  2009-02-16 07:08 -------
>I rather expect that will never happen as the #line bit is there for
compatibility with the c preprocessed tool stack (lex, yacc, CPP and any other pre existing tools/editors that need to remap line numbers)

But those tools normally create or consume C code. D isn't C, so I don't see how this is relevant. For example Java doesn't support #line as far as I know, so it has the same limitation. (C# does support it, but it also supports #if, #define, etc).

Are there any such tools where it is relevant?


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http://d.puremagic.com/issues/show_bug.cgi?id=2660





------- Comment #5 from shro8822@vandals.uidaho.edu  2009-02-16 13:18 -------

I'll admit it is not public domain, but I have a tool for translating c# into D that uses #line all over the place and a tool that takes a file with #line directives and finds lines that assume a given file name/line number

I guess my point is that #line is a bit of a standard and I see no point in breaking from it. Even getting another operator is a bit of a hard sell as the only uses for # I known of are out-of-band annotations (C's usage and bash like comments) so I would be hesitant to give it any other use.


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http://d.puremagic.com/issues/show_bug.cgi?id=2660





------- Comment #6 from wbaxter@gmail.com  2009-02-16 19:27 -------
(In reply to comment #5)
> I'll admit it is not public domain, but I have a tool for translating c# into D that uses #line all over the place and a tool that takes a file with #line directives and finds lines that assume a given file name/line number

Can't you just spend like 2 seconds changing that to look for pragma(line..)
instead of #line?

> I guess my point is that #line is a bit of a standard and I see no point in breaking from it. Even getting another operator is a bit of a hard sell as the only uses for # I known of are out-of-band annotations (C's usage and bash like comments) so I would be hesitant to give it any other use.
> 

I think here, too, removal of #line should be conditioned upon some agreement about what to do with it once it's free.


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http://d.puremagic.com/issues/show_bug.cgi?id=2660





------- Comment #7 from shro8822@vandals.uidaho.edu  2009-02-16 20:09 -------
(In reply to comment #6)
> 
> Can't you just spend like 2 seconds changing that to look for pragma(line..)
> instead of #line?
> 

That's not my point, my point is that there are tools in play that deal with #line and I rather suspect nothing at all to deal with pragma(). I see a cost to the switch and no gain.

> 
> I think here, too, removal of #line should be conditioned upon some agreement about what to do with it once it's free.
> 

I guess I'm saying the same thing, but with the added assertion that I don't think you will come up with something better to do with it


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http://d.puremagic.com/issues/show_bug.cgi?id=2660





------- Comment #8 from maxmo@pochta.ru  2009-02-18 05:00 -------
AFAIK # is used as a prefix operator in miniD


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http://d.puremagic.com/issues/show_bug.cgi?id=2660





------- Comment #9 from jarrett.billingsley@gmail.com  2009-02-18 08:25 -------
Quite right.  It's borrowed from Lua and means "length" or "size".  Which, I assume, was originally borrowed from math.


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