I think if you have the op for dereferencing, you don't need the
additional ops for
getting the type of the reference. Maybe in a typed VM it would make
sense,
but in Parrot, everything is a reference to a PMC, and a PMC knows
what type it is.
At least that is my opinion. I think the deref op makes sense, but
not the "ref type" ops. Just deref it to a P register and use the existing
typeof op on it directly. For a ref to a ref to a ref you'd have to do
that
anyway.
-Melvin
Leopold Toetsch <[EMAIL PROTECTED]>
10/08/2003 11:12 AM
To: P6I <[EMAIL PROTECTED]>
cc:
Subject: References ...
... are autogenrated sice some time. They delegete all but a few methods
to the refered PMC. [1]
But there are some pieces missing IMHO:
There is no means to get at the type of what the Ref refers too.
And we can't dereference the ref.
I'm thinking of 2 new ops:
deref Px, Py # set Px to what Ref Py refers to
ref S0, Py # := typeof S0, Py->referee
ref I0, Py # := typeof I0, Py->referee
The "deref" opocde could call vtable->get_pmc, which isn't covered by
any opcode yet (assign does a set_pmc - but we don't have the opposite).
This could be also useful for Keys. We can do:
new P0, .Key
new P1, .PerlString
set P1, "key"
assign P0, P1
But there is no opcode to get the PerlString out of the key.
Comments welcome,
leo
[1]
new P1, .PerlString
set P1, 42
new P0, .Ref, P1
print P0
print "\n"
inc P1 # or inc PO
print P0
print "\n"
typeof S0, P0
print S0
print "\n"
typeof S0, P1
print S0
print "\n"
end
42
43
Ref
PerlInt
