Why version() ?

[Ary Borenszweig]

Ary Borenszweig escribió:
> Jason House escribió:
>> Walter Bright Wrote:
>>
>>   
>>> 5. Why can't one 'version out' syntax that is not recognized by the 
>>> compiler?
>>>
>>> The problem is that supporting this requires semantic analysis in 
>>> order to successfully lex and parse the source code. Breaking this 
>>> will make the lexing and parsing an order of magnitude harder for 
>>> third party tools to do. If you need to 'comment out' a section of 
>>> syntactically invalid code, use the /+ ... +/ nesting comment.
>>
>> Would you be willing to introduce an alternative to /+ +/ which would 
>> be treated differently by the D1 and D2 compilers? Here are some 
>> examples with no attempt at creativity:
>> beginD1 endD1
>> D1 D1 (works like string delimiters)
>> /D2 D2/
> 
> Why not have special versions like D1, D2, D3 for the compiler to treat 
> them differently? If a version(DX) is found that is not the current's 
> compiler version, it just consumes tokens (counting opening and closing 
> of brackets, etc.) until the curly's close. Much like the asm statement.

Ah, mmm... the lexer also needs to know this. Doesn't work. :-(

Well, it could work if you lookahead a few tokens...