🚀 go-pugleaf

In article 76E5@cs.tu-berlin.de, Roman Lechtchinsky <wolfro@cs.tu-berlin.de> writes:
>
>The DWP defines:
>
>A constructor declared without the  function-specifier  explicit  that
>  can  be called with a single parameter specifies a conversion from the
>  type of its first parameter to the type of its  class. [class.conv.ctor]
>
>Now, to me this means that a copy constructor is a converting constructor 
>since it takes a single parameter which is a reference to an object of the 
>class ( I don't think that this is intended ). 

I don't think it matters. The conversion is the identity conversion. In
places where conversions are required, there is almost always more than
one way to achieve the conversion. (Often there is an infinite number
of possible conversion sequences, such as short->int->short->int->short->...->int.)
The explicit rule in such cases is to choose the shortest possible sequence
of conversions.

Suppose a copy constructor T::T(const T&) is viewed as a conversion from T to
T. If such a conversion is "needed", the shortest conversion sequence must be
chosen. That would be the null sequence, and so the copy ctor would never
be used or even considered for that purpose. (Just as the sequence
int->Rational->float would never be considered in converting an int to
a float.)

---
Steve Clamage, stephen.clamage@eng.sun.com



[ comp.std.c++ is moderated.  To submit articles: Try just posting with your
                newsreader.  If that fails, use mailto:std-c++@ncar.ucar.edu
  comp.std.c++ FAQ: http://reality.sgi.com/austern/std-c++/faq.html
  Moderation policy: http://reality.sgi.com/austern/std-c++/policy.html
  Comments? mailto:std-c++-request@ncar.ucar.edu
]