Re: Recursively walk a hash to get to an element

There's an typo in the code; the code block in the reduce statement should be

{ \($$a->{$b}) }
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Also, when I tried the code as given (after fixing the above typo), I got the error:

% perl rec_walk.pl
Can't call method "List::Util::reduce" on unblessed reference at rec_w
+alk.pl line 9.
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Here's the full code of the script that caused that error:

use strict;
my %myhash;
$myhash{bedrock}{flintstone}{fred} = 3;

my $ref = pointer_to_element(\%myhash, qw(bedrock flintstone fred));

sub pointer_to_element {
  require List::Util;
  return List::Util::reduce { \($$a->{$b}) } \shift, @_;
}
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I couldn't figure out why the error, so I switched the code to

use List::Util 'reduce';
sub pointer_to_element {
  return reduce { \($$a->{$b}) } \shift, @_;
}
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and it worked great. Tres cool.

the lowliest monk

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Re^2: Recursively walk a hash to get to an element by ihb (Deacon) on Mar 31, 2005 at 03:27 UTC
The reason of the error is that reduce uses a prototype not yet seen when the return statement is compiled. It's therefore interpreted as indirect object syntax (`method { STATEMENTS } LIST`), being `do { STATEMENTS }->method(LIST)` with direct syntax. The way to fix this is to call `&reduce` like `List::Util::reduce(sub { ... }, LIST)`. `ihb` See perltoc if you don't know which perldoc to read!	[reply] [d/l] [select]

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Re^2: Recursively walk a hash to get to an element
by ihb (Deacon) on Mar 31, 2005 at 03:27 UTC

The reason of the error is that reduce uses a prototype not yet seen when the return statement is compiled. It's therefore interpreted as indirect object syntax (method { STATEMENTS } LIST), being do { STATEMENTS }->method(LIST) with direct syntax. The way to fix this is to call &reduce like List::Util::reduce(sub { ... }, LIST).

ihb

See perltoc if you don't know which perldoc to read!

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