Q: Array vs SArray

[Leopold Toetsch]

The set_integer_native() vtable method of arrays is implemented 
inconsistently. The old historical way in Array was to set an initial 
size. My implementation in SArray OTOH only reserves the needed store, 
but doesn't change the element count.
    new P0, .SArray
    set P0, 2
    set I0, P0	# SArray.elements()
    print I0
    new P1, .Array  # or .PerlArray
    set P1, 2
    set I1, P1	# Array.elements()
    print I1
    print "\n"
    end
02

This is bad. But it gets worse: You can do "push P0, x" twice on the 
SArray, filling the first 2 elements. You can't do that on Array. It 
would set the element #2 which is beyond the preset element count - push 
is currently not usable for Array PMCs. (PerlArray works basically like 
Array but does auto-extend)

I'd like to unify the behavior and get best from these two worlds:
1) can set an initial store size and (if really needed)
2) can set an initial element count, not-yet set values are NULL.
One further note, while at Array/PerlArray: the class dependency is 
suboptimal. PerlArray isa Array isa list. The underlying list is 
auto-extending and does no bounds checking. Array does bounds-checking. 
PerlArray doesn't bounds check. So for better performace and simpler 
code, the dependency of PerlArray and Array should be swapped.

Comments welcome,
leo