Re: [boost] Re: lexical_cast question

From: Kevlin Henney (kevlin_at_[hidden])
Date: 2001-02-26 02:32:00

In message <01022215243600.04969_at_chronos>, Vladimir Prus
<ghost_at_[hidden]> writes
>Kevlin Henney wrote:
>
>>>At the moment lexical_cast<string>(whatever) will fail if 'whatever' 
>decides 
>>>to insert spaces in its representation. I think that it is not very 
>>>convenient. 
>
>>You're right that it's not convenient, but I would hesitate to make
>>std::string a special case.
>
>I really think that making std::string a special case is OK, because:
>1. It will always be a special case, either inside lexical_cast or in user 
>code.

I was referring to std::string as a special case of std::basic_string,
but that's something that can be accommodated without a problem, and
also to other string classes. However, in the latter case if the 'API'
is opened up, that offers a hook for extension.

>3. Actually, string's operator>> has no choice but to stop when it encounters
>space, for it has no knowledge what was put in the stream. 

Well, it does have a choice, but that's a historical design decision we
can't easily retake :->

>> A more general solution would be to replace the expression
>
>>      ... || !(interpreter >> result) || ...
>
>> by
>
>>       ... || !interpret(interpreter, result) || ...
>
>Yes, this is shurely better. What are chances that something like this will 
>be added?

High :-) When I get a moment I will try to roll this change in with the
proposed floating point mods, plus tests and changes to docs.

Kevlin
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