[boost] Re: [optional]output

From: David Abrahams (dave_at_[hidden])
Date: 2005-03-09 20:20:41

"Peter Dimov" <pdimov_at_[hidden]> writes:

> David Abrahams wrote:
>> "Peter Dimov" <pdimov_at_[hidden]> writes:
>>
>>> David Abrahams wrote:
>>>> If you want to be unambiguous, it has to be more like:
>>>>
>>>>     [hello] <- a non-empty optional<std::string>
>>>>     []      <- a non-empty optional<std::string> (the string is
>>>>     empty) _       <- an empty optional<T>
>>>
>>> My preference is
>>>
>>>    hello
>>>
>>>    _
>>>
>>> A string can never be output "correctly", no matter what the
>>> delimiters are ("a] [b").
>>
>> I disagree.  You can generate escapes:
>>
>> [a\] \[b]
>>
>> or if you like,
>>
>> [a\]\ \[b]
>
> I should have been more clear. You shouldn't attempt to fix the output of a 
> std::string in optional<>'s operator<<. The proper way to make a std::string 
> bi-directional is by defining appropriate operator<< and operator>> 
> overloads for std::string. As these operators are already defined and are 
> not bi-directional in the general case, optional<std::string> should not 
> attempt to provide extra bi-directionality.

Okay, I don't neccessarily disagree, but I don't agree yet either.
Why?

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com