🚀 go-pugleaf

In article 95Sep27095444@physics10.Berkeley.EDU, bboreham@csfp.co.uk (Bryan Boreham) writes:
>
>Is anyone else alarmed that a cast to a reference type can silently
>convert anything, even when the relevant object or pointer cast would
>be disallowed?

No, and the reference cast is allowed only if the comparable pointer cast
is allowed anyway. In any event, you should not use old-style casts at all.

If you use static_cast or dynamic_cast, the cast will be permitted only
if it is safe. Otherwise it will fail at compile time with an error, or
at run time with a null return or a "bad_cast¨ exception.


>
>  A* a;
>  B* b = (B*)a;          // Error: Cannot cast from A* to B*.
>  B& c = (B&)a;          // this is OK

The pointer cast may be a programming error, but is allowed by the language
rules. The old-style pointer cast says "Trust me, I know what I am doing."
The compiler must allow it.

>Newcomers may be taught that references are "just like objects except
>cheaper to copy", or "just like pointers except you don't have to
>dereference them".  As far as casting goes, references are dangerous.

No, old-style casts are dangerous, period. References are merely not an exception.
---
Steve Clamage, stephen.clamage@eng.sun.com



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