So in short, returning an array ref is easier to code and can be significantly more efficient if you're returning a lot of values

Been playing around with some stuff, trying to verify the above quote.

I came up with this (perhaps it's sophistic): 
use warnings;
use Benchmark;

use Inline C => Config =>
    BUILD_NOISY => 1;

use Inline C => <<'EOC';

void foo(AV * x) {
     dXSARGS;
     SV ** elem;
     int len, i;
     
     len = av_len(x) + 1;

     sp = mark;

     for(i = 0; i < len; i++) {
        elem = av_fetch(x, i, 0);
        XPUSHs(*elem);
     }

     PUTBACK;
     XSRETURN(len);
}

AV * bar(AV * x) {
     dXSARGS;
     SV ** elem;
     int len, i;

     sp = mark;

     len = av_len(x) + 1;

     for(i = 0; i < len; i++) {
        elem = av_fetch(x, i, 0);
        XPUSHs(*elem);
     }

     return x;
}

EOC

$len = 2000000;

@x = ();

for(1 .. $len) {push @x, $_}

timethese (1, {
 'ref'  => '$ret = bar(\@x)',
 'list' => '@ret = foo(\@x)',
});

[download]
For me that produces: 
Benchmark: timing 1 iterations of list, ref...
      list:  1 wallclock secs ( 0.36 usr +  0.11 sys =  0.47 CPU) @  2
+.13/s (n=1
)
            (warning: too few iterations for a reliable count)
       ref:  0 wallclock secs ( 0.11 usr +  0.00 sys =  0.11 CPU) @  9
+.17/s (n=1
)
            (warning: too few iterations for a reliable count)

[download]
The difference is certainly *measurable*, but I wonder if it's all that *significant* (given the size of the array). I also wonder a little about the assertion that it's easier to return an AV* than a list. For most of the stuff that I have done, I've found it easier to return a list - even though the coding may involve additional keystrokes. (Admittedly, most of the stuff I've done is Inline based ... and I'm a simpleton :-)

Cheers,
Rob

In reply to Re^2: Return array or list from an XSUB? by syphilis
in thread Return array or list from an XSUB? by smee30

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