Re: Amazing syntax of push (was Re: Removing duplicates in Array of Array)

The seemingly obvious reasons that I can come up with are (a) either array in push @{ @p } , ... is magically being used as an array reference; (b) or the array deference is being optimized out. Given ...

use warnings; use strict;

my @p;
my $p = \@p;
push @p      , [ 1 , 2 ];
push @{ $p } , [ 3 , 4 ];
push @{ @p } , [ 5 , 6 ];
[download]

... output of perl -MO=Terse file (5.8.8; in case somebody can make more sense of it than I can) ...

LISTOP (0x875ffa8) leave [1]
    OP (0x86ed188) enter
    COP (0x86ed748) nextstate
    OP (0x87255e0) padav [1]
    COP (0x8722170) nextstate
    BINOP (0x8760098) sassign
        UNOP (0x872ec78) refgen
            UNOP (0x8760020) null [141]
                OP (0x872ff90) pushmark
                OP (0x873a360) padav [1]
        OP (0x873b480) padsv [2]
    COP (0x86f4b28) nextstate
    LISTOP (0x87605c0) push [3]
        OP (0x8724410) pushmark
        OP (0x86ed670) padav [1]
        UNOP (0x87244d0) srefgen
            UNOP (0x8760188) null [141]
                LISTOP (0x8760110) anonlist
                    OP (0x8728370) pushmark
                    SVOP (0x872a238) const [8] IV (0x8753ef8) 1
                    SVOP (0x872fec8) const [9] IV (0x8753eec) 2
    COP (0x86d7c40) nextstate
    LISTOP (0x8761420) push [5]
        OP (0x86f5a00) pushmark
        UNOP (0x8722228) rv2av [4]
            LISTOP (0x8760638) scope
                OP (0x86edc08) null [174]
                OP (0x87223a8) padsv [2]
        UNOP (0x86f58d0) srefgen
            UNOP (0x8761270) null [141]
                LISTOP (0x8760a58) anonlist
                    OP (0x86f5058) pushmark
                    SVOP (0x86f5430) const [10] IV (0x8753ebc) 3
                    SVOP (0x86f5098) const [11] IV (0x8753eb0) 4
    COP (0x8736298) nextstate
    LISTOP (0x87615e0) push [7]
        OP (0x8711da0) pushmark
        UNOP (0x86f3990) rv2av [6]
            LISTOP (0x87618c8) scope
                OP (0x87361b8) null [174]
                OP (0x86f7370) padav [1]
        UNOP (0x8711c78) srefgen
            UNOP (0x8761728) null [141]
                LISTOP (0x8761b38) anonlist
                    OP (0x86f3ba0) pushmark
                    SVOP (0x86f3f10) const [12] IV (0x8753e8c) 5
                    SVOP (0x86f3fc0) const [13] IV (0x8753e80) 6
[download]

perl 5.8.8 & 5.10.0 did not have any problems in parsing the code.

Comment on Re: Amazing syntax of push (was Re: Removing duplicates in Array of Array) Select or Download Code

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Re^2: Amazing syntax of push (was Re: Removing duplicates in Array of Array) by ikegami (Patriarch) on Sep 04, 2008 at 08:31 UTC
`rv2av` doesn't seem to care whether it gets an array reference or an array. Update: This is confirmed by BrowserUK's less specific test and by looking at the 5.8.8 source: `PP(pp_rv2av) { ... if (SvROK(sv)) { ... av = (AV)SvRV(sv); ... } else { if (SvTYPE(sv) == SVt_PVAV) { av = (AV)sv; ... } ... } ... ...return something derived from av... }` [download]	[reply] [d/l] [select]