Convert string to wchar.

[Jacob Carlborg]

On 2011-08-03 08:38, Jonathan M Davis wrote:
> On Wednesday 03 August 2011 08:29:09 Jacob Carlborg wrote:
>> On 2011-08-02 19:51, Jonathan M Davis wrote:
>>>> I tried to convert a string into a wchar, but that didn't compile
>>>> because of this template constraint:
>>>>
>>>> https://github.com/D-Programming-Language/phobos/blob/master/std/conv.
>>>> d#L17 70
>>>>
>>>> Is there a way to convert a string into a wchar?
>>>
>>> Does that even make sense? What do you want it to do, convert the first
>>> code point to a wchar and throw if there's more than one character in
>>> the string? That's like asking whether you can covert between a
>>> container of ints and an int. I would never expect std.conv.to to
>>> support that. Not to mention, you shouldn't normally be using char or
>>> wchar by themselves, because they might not be valid code points.
>>> Normally, only dchar should be used when representing an individual
>>> character. If you want this, I'd suggest that you simply do something
>>> like
>>>
>>> cast(wchar)str.front
>>>
>>> What you're asking for is inherently unsafe as far as unicode goes.
>>>
>>> - Jonathan M Davis
>>
>> I'm working on a serialization library and I intend to support as many
>> types as possible. So if someone serializes a single wchar I need to be
>> able to deserialize it. Since the serialized data is represented by a
>> string, in this case, I need to convert a string containing a single
>> character to a wchar when deserializing.
>>
>> Yes, convert the first code point to a wchar and then throw if there's
>> more the one character in the string.
>
> Well, while it's understandable that you have to cover pretty every possible
> case of converting to and from a string with what you're doing, I don't think
> that it's at all reasonable to have std.conv.to convert a string to any
> character type, let alone one other than dchar. It's almost always a horrible
> idea and should _not_ be encouraged. So, I'd advise you to just find a way to
> deal with it appropriately in your own code. I think that it would be a very
> bad idea for std.conv.to or anything else in Phobos to support such a
> conversion.
>
> - Jonathan M Davis

Ok, fair enough.

-- 
/Jacob Carlborg