On Feb 24, 2010, at 8:44 AM, Jeff wrote:
Notice on the second run the plan is still "beef" when it was set to
49abf0 (which when passed as the arg is correct)
Any perl gurus have any further info on this? It was a bit
surprising to encounter this. I'm guessing it has something to do
with variable scope and the fact plperl funcs are just anonymous
functions.
Stuffing it in $_SHARED seems to work fine and ends up with results
as one would expect.
Thanks to RhodiumToad on irc for the pointer - posting this here for
posterity.
From perlref:
"Thus is because named subroutines are created (and
capture any outer lexicals) only once at compile time, whereas
anony-
mous subroutines get to capture each time you execute the
'sub' opera-
tor. If you are accustomed to using nested subroutines in
other pro-
gramming languages with their own private variables, you'll
have to
work at it a bit in Perl. The intuitive coding of this type
of thing
incurs mysterious warnings about "will not stay shared". For
example,
this won't work:
sub outer {
my $x = $_[0] + 35;
sub inner { return $x * 19 } # WRONG
return $x + inner();
}
A work-around is the following:
sub outer {
my $x = $_[0] + 35;
local *inner = sub { return $x * 19 };
return $x + inner();
}
Now inner() can only be called from within outer(), because of
the tem-
porary assignments of the closure (anonymous subroutine). But
when it
does, it has normal access to the lexical variable $x from the
scope of
outer().
--
Jeff Trout <jeff@xxxxxxxxxxxxx>
http://www.stuarthamm.net/
http://www.dellsmartexitin.com/
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