Re^2: Making each(@ary) work on 5.10?

Neat! tobyink++

All I need now is something like, say feature::each_on_array, so that the code below:

use feature::each_on_array;
@a = (1..1000);
while (my ($idx, $item) = each @a) { }
[download]

will run on Perl 5.10 and will take no performance hit on 5.12+.

Are you interested in packaging Tie::ArrayAsHash for distribution? There's already Tie::Array::AsHash on CPAN. Perhaps rethink the name because your solution also provides aeach().

package feature::each_on_array;

use strict;
use warnings;
use Tie::ArrayAsHash qw(aeach);

sub import {
    return unless $^V lt 5.16.0;
    no strict 'refs';
    my @caller = caller;
    *{"$caller[0]::each"} = \&aeach;
}

1;
[download]

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Re^3: Making each(@ary) work on 5.10? by tobyink (Canon) on Jul 27, 2012 at 07:03 UTC
As I said, there's a reason I called it `aeach` instead of `each`. You can define your own sub called `each`, but if you try to actually use it, you just get the Perl built-in. This goes right down to the Perl tokenizer. There are only three ways to call your own `each` function: qualify your call with the package name (`MyPackage::each(@array)`), prefix it with an ampersand (`&each(\@array)` - note that prototype will be ignored, so you need to pass a reference), or call it as a method (but methods can't be called on unblessed arrays, unless you use autobox). Now, it is palso ossible to overwrite the core `each` with your own: `use Tie::ArrayAsHash 'aeach'; BEGIN { *CORE::GLOBAL::each = \&aeach };` [download] However, this is a global override rather than being package scoped or lexically scoped. (You might think that it would introduce infinite recursion because `aeach` internally calls `each`, but actually it does not. This is because `aeach` has already been compiled when the override happens, so is not affected by the override.) To override `each` for just a lexical scope is a much harder proposition. `perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'`	[reply] [d/l] [select]
Re^4: Making each(@ary) work on 5.10? by sedusedan (Pilgrim) on Jul 27, 2012 at 09:00 UTC
I don't think you're entirely correct. The code which I posted (feature::each_on_array) works on my 5.10. And I did not override "each" globally, only on the caller's package. `% perl -I. -Mfeature::each_on_array -E'say $^V; @a = (qw/a b c/); whil +e (($i, $e) = each @a) { say $i, $e }' v5.10.1 0a 1b 2c` [download] vs `% perl -I. -Mfeature::each_on_array -E'say $^V; @a = (qw/a b c/); whil +e (($i, $e) = each @a) { say $i, $e } package Foo; @b = (qw/a b c/); +while (($i, $e) = each @b) { say $i, $e }' Type of arg 1 to each must be hash (not array dereference) at -e line +1, near "@b) "` [download] Perl here does call our subroutine's each. I'll be packaging this as a CPAN module; I need this to work on a 5.10 box, and I want to see CPAN Testers result. I'm including Tie::ArrayAsHash for now.	[reply] [d/l] [select]
Re^5: Making each(@ary) work on 5.10? by tobyink (Canon) on Jul 27, 2012 at 13:10 UTC
I stand corrected. Here's the latest version, tested in Perl 5.8.9, 5.10.1 and 5.16.0... Read more... (2 kB) The import options are these: `# Import nothing, but use the tied hash interface. use Tie::ArrayAsHash; # Import 'aeach'. use Tie::ArrayAsHash qw(aeach); # Import 'aeach', but call it 'each'. use Tie::ArrayAsHash qw(each); # Import 'aeach' with both names. use Tie::ArrayAsHash qw(-all); # Import 'each' if Perl lt 5.11.0; import 'aeach' regardless. use Tie::ArrayAsHash qw(-auto); # Import 'aeach' renamed it to whatever you like. use Tie::ArrayAsHash aeach => { -as => 'p512each' };` [download] Still needs proper documentation and test suite, and maybe a better name. `perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'`	[reply] [d/l] [select]
Re^6: Making each(@ary) work on 5.10? by sedusedan (Pilgrim) on Jul 27, 2012 at 14:08 UTC
Re^7: Making each(@ary) work on 5.10? by tobyink (Canon) on Jul 28, 2012 at 09:48 UTC
Re^4: Making each(@ary) work on 5.10? by Anonymous Monk on Jul 27, 2012 at 07:44 UTC
To override each for just a lexical scope is a much harder proposition. ex::override maybe? `{ use ex::override 'each' => \&aeach; ... no ex::override 'each'; }` [download]	[reply] [d/l]
Re^5: Making each(@ary) work on 5.10? by tobyink (Canon) on Jul 27, 2012 at 12:36 UTC
I did look at ex::override, but `each` doesn't seem to show up in that grep on toke.c that they suggest, which seemed to suggest that ex::override would not work. `perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'`	[reply] [d/l]