Re: [Boost-users] [Q] using boost operators return types

Subject: Re: [Boost-users] [Q] using boost operators return types
From: V S P (toreason_at_[hidden])
Date: 2009-03-23 13:04:17

Hi,
please ignore this last question
I figured out the problem
I was using decPlus  which adds 0 to the argument
and I needed to use decAdd (which adds the two numbers)

thank you again,
Vlad

On Mon, 23 Mar 2009 12:54 -0400, "V S P" <toreason_at_[hidden]> wrote:
> Thank you for the reply
> 
> I am still a bit lost
> 
> for example, the doc says
> 
> 
> subtractable<T>
> 
> produces  T operator-(const T&, const T&)
> 
> It requires:
> "
> T temp(t); temp -= t1.
> "
> 
> 
> so does this mean
> T& operator -= (const T& )    ?
> 
> 
> 
> 
> --- 
> this is a separate question:
> 
> I have implemented the <addable> tempalte with +=
> (as in the point example, but made it return a reference)
> 
> then I do 
> cmoney_t  a("300");
> cmoney_t  b("100");
> 
> a+=b;
> 
> 
> and I see in the debugger that 
> the *this in the operator += points to 100, not to 300
> 
> I am sure I am doing something wrong, but I thought 
> in the += operator, *this  would mean the value of "a" variable
> not "b".
> 
> Is at least my understanding correct, that *this should be pointing to
> 300,
> and not 100?
> 
> 
> 
> thank you again,
> Vlad
> 
> 
> 
> 
> 
> 
> 
> 
> On Mon, 23 Mar 2009 10:41 -0500, "Alan M. Carroll"
> <amc_at_[hidden]> wrote:
> > At 09:55 AM 3/23/2009, V S P wrote:
> > >I am using this example
> > >http://www.boost.org/doc/libs/1_38_0/libs/utility/operators.htm#example
> > >
> > >but cannot understand
> > >why object is returned from those operators and not an object reference
> > 
> > That certainly is odd. It means that the following code will not work as
> > expected:
> > 
> > point x(0,0), y(1,0), z(0,1);
> > (x += y) += z; // x is (1,0), not (1,1).
> > 
> > >second, I do not quite understand, what exactly is a set of 
> > >'automatically generated' operators and would I figure that out.
> > 
> > It is documented in the comments of the example you cite, and listed in
> > the table[1] just below.
> > 
> > [1]
> > http://www.boost.org/doc/libs/1_38_0/libs/utility/operators.htm#smpl_oprs
> > 
> > _______________________________________________
> > Boost-users mailing list
> > Boost-users_at_[hidden]
> > http://lists.boost.org/mailman/listinfo.cgi/boost-users
> -- 
>   V S P
>   toreason_at_[hidden]
> 
> -- 
> http://www.fastmail.fm - I mean, what is it about a decent email service?
> 
-- 
  V S P
  toreason_at_[hidden]
-- 
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