Safer casts

[Yigal Chripun]

IMHO, your reply makes perfect sense for C/C++ but not for D.
specifically because D has other facilities to handle those cases.
a dchar (or [w]char) _must_ always contain valid data. if you need to
store other encodings you can use ubyte instead which does not limit you
to a specific bit pattern (this is why D has it in the first place...)
the above example of slices can be easily dealt with since (unlike in
C/C++) D arrays know their length. this is similar to the fact that D
checks bounds on arrays and throws on error (in debug mode) whereas
C/C++ does not. IMO, the D implementation itself (both the compiler and
the runtime) need to make sure chars are always valid. this should not
be something optional added via a library.

I agree with you notion of levels, I just think D provides for much
better facilities for low-level coding compared to using unsafe C/C++
conventions.

    int n;
    dchar c = cast(dchar)n;
    dchar d = cast!(dchar)n;

in the above code, the second one should be used and it might throw. the
first simply does not make any sense and should produce a compiler error
because you cannot convert an int value to a dchar (unless it's a one
digit int)

<off topic rant>
What worries me most about D is the fact that D becomes an extension to C++.
The whole idea behind D was to create a new language without all the
baggage and backward compatibility issues of C++.
I don't want a slightly more readable version of C++ since I'll get that
with C++0x.
c++ programmers want D to have a D "stl" and a D boost. that's wrong!
STL is badly designed and employs massive amounts of black magic that
ordinary people do not understand. (I suffer at work while writing in
C++). in what world does it make sense to mark an abstract method with
"=0;" at the end, especially when the method is horizontally long and
that gets to be off screen!
D should be written with a D mindset which should be the best
ingredients extracted from all those languages D got its influences
from: java, C#, python, ruby, c/c++, etc. Tango is a good example of
designing such a new D mindset, IMO. Phobos is not, since it's merely C
code written with D syntax, with all those new shiny code Andrei added
which is C++ code written with D syntax. I appreciate his great
expertise in C++, but I already can use C++ libraries in C++ without
learning a new language. D needs to be better. *much* better.
</rant>

--Yigal