[boost] Re: lexical_cast "Future directions"

From: Early Ehlinger (earlye_at_[hidden])
Date: 2002-12-29 14:10:32

[Sorry for the top-posted reply... OE is giving me fits...]

This is an interesting argument.  In other words, lexical_cast is, by
definition, conversion through a stream.  Therefore, one cannot expect a
string with whitespace to exit as it went in.

Perhaps what is really needed is a different pseudo-cast, e.g.,
symantic_cast< >, which has different goals more in synch with what we are
trying to accomplish, which is conversion from any type to another with
minimized loss of symantic value.

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"Thomas Witt" <witt_at_[hidden]> wrote in message
news:200212291924.36397.witt_at_ive.uni-hannover.de...
Hi,
On Sunday 29 December 2002 01:29, Terje Slettebø wrote:
> > Is this the way lexical_cast is intended to work?
>
> No, Kevlin has acknowledged that this is a known problem with the current
> version of lexical_cast, the handling of whitespace in strings and
> characters.
I am still uncertain whether this is a problem with lexical_cast and whether
it should be fixed.
The stated purpose of lexical_cast is type conversion through string
representation. I think this is a simple but powerful concept.
To me the actual problem is not in lexical_cast but in the
std::basic_strings
stream operator semantics. Basically you cannot read strings containing
whitespace as a whole. I.e. the integrity of a string containing whitespace
is lost once you streamed it.
This is a fundamental if at  times undesirable property of std::basic_string
and char const* for that matter. I don't know whether it is a good idea for
lexical_cast to try to fix it.
Just my 2c
Thomas