Re: [boost] RE: IO Formatters and lexical_cast

From: Vladimir Prus (ghost_at_[hidden])
Date: 2004-03-12 08:11:33

Reece Dunn wrote:

> >  2) The output operator puts spaces after '[', before ']',
> >     and after each ','; whereas the input operator expects
> >     no spaces at all; if spaces were present, a bad_lexical_cast
> >     exception was thrown. I think it is really important that
> >     operator>> can deal with an output which was generated by <<;
> >     stated in terms of lexical_cast,
> >
> >        lexical_cast<T>( lexical_cast<string>( t ) ) == t
> >
> >     should hold for any T t.
>
> I stripped and skipped the spaces during the read operation to allow for
> the read operation to accommodate input variations, e.g. [ a, b ]; [a, b]
> and [ a,b ] would be read by the same formatter, making it easier to
> interoperate with data generated from other sources. I could make this a
> configurable option that does not strip the spaces by default.

It's really good question if the >> operator should be prepared to find a 
stream which has 'skipws' bit unset.  Given that streams usually generate 
human-readable data, skipping whitespace is a common behaviour, and I'd say 
that 'noskipws' manipulator should be used only for special circumstances.

So, in my opinion lexical_cast<T> should not use 'noskipws', and not force 
other libraries to manually skip whitespace.

- Volodya