Re: Why is there no input value optimization?

"P. Areias" <>
Fri, 13 Apr 2012 11:40:49 -0700 (PDT)

In regard to extending the language: what if we annotate
class declarations?

typedef std::string by_ref rstring;

// Old C++
void Widget::set_name(std::string const & name)
  this->name = name;


// Hand optimized free C++
void Widget::set_name(rstring name)
  this->name = name;


// Hand optimized free C++
void set_name(rstring name)
  name += ".xml"; // error: rsting is a constant type
  this->name = name;


// Hand optimized free C++
void set_name(rstring name)
  rsting new_name(name);
  new_name += ".xml";
  this->name = name;


The explicit copy of arguments (when required) is the trademark of
Fortran (even 2003), since ALL arguments are passed by reference. C++
approach requires more discipline but In addition, the in / out /inout
safeguards are also in the intent() identification of arguments.

So it is either:

1) All (non-constant) references with explicit deep copies inside the
functions. Safeguards may be used: Fortran 95-2003
2) A variety of argument possibilities (in the end, pointers and
values). Copies are synthesized: C++
3) Possibly a VM to deal with more intricate situations. .NET

Wasn't B. Stroustrup intimately familiar with Fortran? I am also (cf.
SIMPLAS, SIMPLASMPC, etc) and prefer, for reasons of coding
efficiency, the C++ way. I never understood the need for C#, as it
seems less productive and more baroque than C++.

In my perspective, this was a difficulty of former Languages
definitely solved by the C++ syntax.

There are still some lacunae in C++ (I wonder why STATIC reflexion is
not in C++11 as any sufficiently complex program would benefit from it
sooner or later), but argument passing is not one (for mature

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