Re: [boost] [Fit] formal review ends 20th March.

Subject: Re: [boost] [Fit] formal review ends 20th March.
From: Paul Fultz II (pfultz2_at_[hidden])
Date: 2016-03-21 18:07:01

On Monday, March 21, 2016 at 4:53:58 PM UTC-5, Edward Diener wrote:
>
> On 3/21/2016 2:04 PM, Paul Fultz II wrote: 
> > 
> > 
> > On Sunday, March 20, 2016 at 9:07:53 PM UTC-5, Gavin Lambert wrote: 
> ... snipped 
> >> I think it's still true that mutable functions are useful 
> >> in more cases -- despite being vulnerable to surprise copies and 
> >> thread-safety issues. 
> >> 
> >> (Having said that, this may be because boost::bind is used in most 
> cases 
> >> where const function objects would otherwise be used, so that custom 
> >> function objects are typically only created where they need to be 
> >> mutable; the code does not yet make extensive use of lambdas.  But I 
> >> don't think my experience is unique.) 
> >> 
> > 
> > I would like to note, that the const requirement only applies to 
> function 
> > objects. You can pass member function pointers to member functions that 
> are 
> > mutable. 
>
> You probably meant to say "You can pass member function pointers for 
> mutable member functions". I would also strongly suggest you use the 
> terms 'const' and 'non-const' when referring to member functions rather 
> than 'const' and 'mutable' in your documentation. The reason I believe 
> this is less confusing is because 'mutable' is a C++ keyword and as a 
> keyword means something entirely different from how you are using it in 
> your documentation. 

How is it different? The mutable keyword is used to signify the function as
non-const. That is when I write:

auto f = [] mutable {};

It is the equivalent of writing a class with a "non-const" call operator 
like
this:

struct local_f{ void operator()() {} // No const here };
auto f = local_f{};
 

> So I think what you really meant to say above would 
> be better expressed as "You can pass member function pointers for 
> non-const member functions". 
>
>
>
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