Re: [boost] Formal Review Request: Boost.String.Convert

Subject: Re: [boost] Formal Review Request: Boost.String.Convert
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2009-02-18 16:44:15

Emil Dotchevski wrote:

> You're presuming that it makes sense to put converting to- and from-
> string into a single interface. For what it's worth, consider that
> sprintf/sscanf are separate interfaces too, despite the many
> similarities and analogies between them.
> 
> Unlike addition and subtraction which are symmetrical, converting to-
> and from- string isn't. For example I searched our source code for
> to_string and from_string. We have 314 occurrences of to_string (in
> 112 source files), and only 33 calls to from_string (in 11 source
> files.) Only 2 files use both to_string and from_string.

I agree that the "from-string" conversion is used less often than 
"to-string". However, that doesn't seem to me as a reason to separate 
the interface. If we forget for a moment about strings, parsing and 
formatting, we have a value of type A and want to get the corresponding 
value of type B. Regardless of the types, we have a common process of 
value and type transformation here. As partial cases it may involve 
parsing, formatting, character transcoding, type promotion - you name it.

There were good examples of such transformation kinds, such as 
string<->wstring conversion and transforms between containers and their 
elements. I assume there can be connection with other Boost libraries, 
like Boost.NumericConversion or Boost.Units. This library has potential 
to become a common framework for conversion facilities that are 
reimplemented here and there quite often. And I feel that a common and 
well recognizable interface is very important for such a framework. That 
is, I think it would be better to use a common name for conversions in 
either direction (well, the direction doesn't matter anyway, from 
perspective of such a framework).