🚀 go-pugleaf

In article 41C67EA6@ecid.cig.mot.com,
Joe Walker <walkerjj@ecid.cig.mot.com> writes:
>Has allowing the following been considered?
>
>  int  length = strlen (some_string);
>  char buffer [ length ];
>
>I.E. allowing non const array sizing.

It is not supported by the C++ draft standard for the same reason it
is not supported by the C standard. It would mean in particular for auto
arrays that the size of the stack frame could not be known until a function
was entered, and could be different at each invocation. On some platforms
that is not a problem. On others it is difficult to implement, or forces
function calls to be much more expensive, or violates the ABI. For
static arrays, some object formats require the array size to be specified
at link time and not deferred until run time.

The standard could say that an implemention is allowed to simulate
variable-sized stack or static arrays by using the heap and automatically
deallocating the storage. IMHO that is not acceptable because in
portable code you would not know whether a declaration like
	char buffer[length];
could fail. It also could turn what looks like a simple declaration into
a heavy-weight operation.

You can get the effect you want by using an auto_ptr and heap allocation,
or by using an array class instead of a C-style array.

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