Re: [boost] [xint] Third release is ready, requesting preliminary review

Subject: Re: [boost] [xint] Third release is ready, requesting preliminary review
From: Chad Nelson (chad.thecomfychair_at_[hidden])
Date: 2010-05-04 11:16:15

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On 05/04/2010 03:58 AM, DE wrote:

>> Hm... I *think* I see it now. At least, some of the time I think I
>> do. :-) Please check my understanding: you're suggesting that I
>> use functions in base_integer to do the allocation, and have them
>> call other functions in base_integer to do the things that are
>> different between fixed_integer and the variable-length integers.
>> But then override those functions in the fixed_integer classes, not
>> as virtual functions, but using CRTP to call the overridden
>> functions. Am I right?
> 
> let me try to explain
> 
> suppose the interface of all your concrete classes (i.e. 'integer',
> 'nothrow_integer' and 'fixed_integer') is homogeneous
> that is all classes have identical names for respective members with
> consistent semantics

Which it should be.

> then each of the classes inherits the base class
> 
>   template<typename type>
>   class base_integer {};
> 
> in the following way
> 
>   class integer : public base_integer<integer>
>   {/*...*/};

Yes, I understand that part.

> then you can write template functions for all types in the following
> manner:
> 
>   template<typename int_type>
>   void foo(const base_integer<int_type>&);
>   template<typename type1, typename type2>
>   void bar(const base_integer<type1>&, const base_integer<type2>&);
> 
> such functions will handle all types derived from base_integer
> providing their type as template argument

Ah, I see now. It wouldn't matter that there couldn't be a common base
class that implements all the common functions, then. I wince slightly
at the implied duplication of compiled code, but I think I see how I can
minimize it. And of course, people will only get that code for the
functions and types that they use.

> [...] please think about it, it is a very powerful design technique, 
> also it may solve a whole lot of troubles now and later

Yes, I can see some problems that it would solve already. It may take me
a few days of playing with it to figure out the most optimal way to use
this, but I like the concept.

> i like this theme very much and will happily write more words on this
> on your demand

Thanks. I think I've got the basic idea, but if I get stuck, I'll ask. :-)
- -- 
Chad Nelson
Oak Circle Software, Inc.
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