Re: [boost] [conversion] try_lexical_cast and 200$

Subject: Re: [boost] [conversion] try_lexical_cast and 200$
From: Michael Caisse (mcaisse-lists_at_[hidden])
Date: 2013-12-12 01:45:16

On 12/11/2013 10:34 PM, Gavin Lambert wrote:
> On 12/12/2013 18:41, Quoth Peter Dimov:

<snip>

> 
>> optional<> is cute because you can use if( auto x =
>> try_lexical_cast<Out>(in) ), but not very convenient for the common
>> case of try_lexical_cast(in1, out1) && try_lexical_cast(in2, out2).
> 
> Optional would work in that case too, eg:
> 
>   if ((out1 = try_lexical_cast<T1, U1>(in1))
>    && (out2 = try_lexical_cast<T2, U2>(in2)))
>   {
>      // both casts worked, do something with out1 and out2
>   }

<snip>

> Also having to specify both types is more annoying than in the bool
> form, where the compiler can infer the parameters.
> 
> (I'm not really a fan of output parameters either, but c'est la vie.)
> 
> On the other hand, if it's not going to resemble "result =
> name<T>(source)" then it's not very cast-like, so the name seems a
> little odd now.  But not enough to bother me much. :)
> 

You still just write:

  out1 = try_lexical_cast<T1>(in1)

where the type of out1 is optional<T1> and the type of in1 is deduced.

-- 
Michael Caisse
ciere consulting
ciere.com