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Subject: Re: [boost] Formal Review Request: Boost.String.Convert
From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2009-02-18 17:29:12

On Wed, Feb 18, 2009 at 2:16 PM, Andrey Semashev
<andrey.semashev_at_[hidden]> wrote:
> Emil Dotchevski wrote:
>>> And what if I write my own class outer_bar that owns bar and also want to
>>> be
>>> ostreamable? I would have to duplicate my operator<< in order to call
>>> either
>>> to_string or to_wstring, wouldn't I?
>> No.
>> You can define template operator<<
> How is that?

What do you mean how? You just define a template operator<< and the
library-supplied to_string/to_wstring templates will bind to it,
assuming the user's calls to_string or to_wstring doesn't bind to a
better overload of to_string/to_wstring.

>> or you can define non-template
>> std::string overload of operator<< only. The user would still be able
>> to call to_wstring, which will bind to a wstring overload if it's
>> available. If not, the generic to_wstring overload will call the
>> std::string operator<< overload, and then convert the result to
>> wstring.
> But I will lose generic ostreamability for my class then.

Even that's not necessarily true, as the library can provide generic
ostream template operator<< overload that's implemented in terms of
to_wstring or to_string or other available operator<< overloads.

I know this is tricky business, but it's tricky for the library
itself. From user's point of view it's much more straight-forward:
they can call to_string, to_wstring, operator<<, whatever, and the
library automatically picks the best way to get it done.

Emil Dotchevski
Reverge Studios, Inc.

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