On Fri, Oct 30, 2009 at 9:48 AM, Bob MacCallum <uncool...@gmail.com> wrote:
> I clearly have more urgent things to do...
>
> @new = @old[map $_*2, 0..$#old/2];
Compact, but not overly readable and op-wise not ultra efficient:
perl -MO=Terse -e ' @new = @old[map $_*2, 0..$#old/2];'
LISTOP (0x100208ca0) leave [1]
OP (0x100202620) enter
COP (0x100208c40) nextstate
BINOP (0x100208c00) aassign [13]
UNOP (0x100209de0) null [142]
OP (0x100208bd0) pushmark
LISTOP (0x100209d00) aslice
OP (0x100209d40) pushmark
LOGOP (0x100209cc0) mapwhile [12]
LISTOP (0x100209c20) mapstart
OP (0x100209c60) pushmark
UNOP (0x100209c90) null
BINOP (0x1002091a0) multiply [6]
UNOP (0x100209140) null [15]
PADOP (0x100209110) gvsv GV
(0x100804e28) *_
SVOP (0x100209170) const [15] IV
(0x100813058) 2
UNOP (0x100209bf0) null
UNOP (0x100206d30) flop
UNOP (0x100206d00) flip [11]
LOGOP (0x100206cc0) range [10]
SVOP (0x1002e3240) const [16]
IV (0x100804fd8) 0
BINOP (0x100206c80) divide [9]
UNOP (0x100206c20) av2arylen
UNOP (0x100206bf0) rv2av [8]
PADOP
(0x100206bc0) gv GV (0x100812fe0) *old
SVOP (0x100206c50) const
[14] IV (0x100813040) 2
UNOP (0x100220830) rv2av [4]
PADOP (0x10020a6f0) gv GV (0x100812fe0) *old
UNOP (0x100209d70) null [142]
OP (0x100209db0) pushmark
UNOP (0x100208eb0) rv2av [2]
PADOP (0x100201c30) gv GV (0x100812f98) *new
-e syntax OK
Compared to:
perl -MO=Terse -e 'my $i; @new = grep { $i != $i } @old;'
LISTOP (0x100208f60) leave [1]
OP (0x100202620) enter
COP (0x100208fd0) nextstate
OP (0x100201c30) padsv [1]
COP (0x100209d50) nextstate
BINOP (0x100209d10) aassign [7]
UNOP (0x100209ca0) null [142]
OP (0x100209ce0) pushmark
LOGOP (0x100206d10) grepwhile [6]
LISTOP (0x100206ca0) grepstart
OP (0x100206ce0) pushmark
UNOP (0x100206d50) null
UNOP (0x100206c70) null
LISTOP (0x100206b50) scope
OP (0x100209150) null [177]
BINOP (0x100209110) ne
OP (0x100220830) padsv [1]
OP (0x1002e3240) padsv [1]
UNOP (0x100206c10) rv2av [5]
PADOP (0x1002091b0) gv GV (0x100813058) *old
UNOP (0x100209c60) null [142]
OP (0x100206c40) pushmark
UNOP (0x10020a6f0) rv2av [3]
PADOP (0x100208eb0) gv GV (0x100812fc8) *new
-e syntax OK
Either way, it's a lot of ops to pull things out of an array.
