Re: [boost] Improving the assignment operators of various Boost types

Subject: Re: [boost] Improving the assignment operators of various Boost types
From: Michael Marcin (mike.marcin_at_[hidden])
Date: 2008-09-09 19:28:36

Peter Dimov wrote:
> Niels Dekker:
> 
>> Basically it was concluded that /if/ an assignment operator is
>> implemented by means of copy-and-swap, it should preferably be done as
>> follows:
>>
>>  T& operator=(T arg)
>>  {
>>    arg.swap(*this);
>>    return *this;
>>  }
> 
> This is well known (although the typical form is swap(arg) instead of 
> arg.swap(*this)). It is not widely used in Boost because it creates 
> problems with some compilers (I recall Borland being one). The "classic" 
> form is, unsurprisingly, much better supported across the board. Things 
> may have improved now, of course.

It also allows you to support move assignment emulation rather elegantly 
using the move library in the sandbox.

Thanks,

Michael Marcin