Re: Is tie inteded to be used in this way? Few question arise

First i have a question not explicitatedd in the original node, about the clearing routine: if i modify my trigger function to manage undef values as in

sub trigger{print "Triggered: ",map {defined $_ ? " $_" : 'UNDEF'}@_,"
+\n"}
[download]

When i try to @arr=undef the tie'magic is called twice. Why?

# rest of the code as before..
print "\tclearing with undef \@arr:\n"     and   undef @arr;
print "\tSetting list:\n" and @arr = qw(a);
print "\tclearing with \@arr=undef:\n"     and   @arr=undef;
print "\tSetting list:\n" and @arr = qw(a);
print "\tclearing with \@arr=():\n"     and   @arr=();

__OUT__
        clearing with undef @arr:
Triggered:  Arraytrigger=ARRAY(0x6ab224)
        Setting list:
Triggered:  Arraytrigger=ARRAY(0x6ab224)
Triggered:  Arraytrigger=ARRAY(0x6ab224) 0 a
        clearing with @arr=undef:
Triggered:  Arraytrigger=ARRAY(0x6ab224)
Triggered:  Arraytrigger=ARRAY(0x6ab224) 0UNDEF
        Setting list:
Triggered:  Arraytrigger=ARRAY(0x6ab224)
Triggered:  Arraytrigger=ARRAY(0x6ab224) 0 a
        clearing with @arr=():
Triggered:  Arraytrigger=ARRAY(0x6ab224)
[download]

Second question: why the code is not triggered when i do a reference to some tied array's elements?

my $ref = \$arr[0];
print "\tsetting by reference:\n"     and   $ref=11;

__OUT__
        setting by reference:
[download]

Third and more important, why i'm no more able to print my array? nor dump or dd it? a simply

print "\@arr [@arr]\n";
[download]

put before clearing the array simply make my program hang, while eating lot of memory in with my Strawberry perl 5.14.2?

L*

There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

Comment on Re: Is tie inteded to be used in this way? Few question arise Select or Download Code

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Re^2: Is tie inteded to be used in this way? Few question arise by choroba (Cardinal) on Apr 28, 2015 at 22:18 UTC
`@arr = undef;` [download] is not the same as `undef @arr;` [download] It assigns undef to the first element of the array, i.e. it's equivalent to `@arr = (undef);` [download] Therefore, it calls CLEAR and STORE, which means two trigger calls. If you store `\$arr[0]` in a $ref, then assigning `$ref = 11` you just remove the reference from $ref. You have to assign to where it points to trigger the magic: `$$ref = 11;` [download] You probably still do `$self->SUPER::STORE($self, @_);` [download] Remove the $self from the arguments and the problem is gone. Update: Here's what caused the problem: when a reference is used as a number, it returns its "address" (which is good for comparing references with ==). Therefore, when you supplied `$self` as the first argument to STORE, it was interpreted as the index where the actual index was stored. The number was probably very high, so the array become gargantuan. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l] [select]
Re^3: tie example.. Code still hangs by Discipulus (Canon) on May 01, 2015 at 16:58 UTC
thanks but even if the code below runs well with all your improvements, as soon as i add a simply `print "\@arr [@arr]\n";` at the end, the program hangs, eating a lot of memory. I dont understand why. use strict; use warnings; sub trigger{print "Triggered: ",map {defined $_ ? " $_" : 'UNDEF'}@_," +\n"} { package Arraytrigger; use Tie::Array; use vars qw(@ISA); @ISA = ('Tie::StdArray'); for (qw(STORE CLEAR PUSH POP SHIFT UNSHIFT)) { my $s = "SUPER::$_"; no strict 'refs'; $_ = sub { &main::trigger; shift()->$s(\@_) }; } } #package main.. tie my @arr, 'Arraytrigger'; print "\tSetting list:\n" and @arr = qw(a b c d e); #print "\tSetting one:\n" and $arr[0]=0; #print "\tpushing:\n" and push @arr,'f'; #print "\tpopping:\n" and pop @arr; #print "\tshifting:\n" and shift @arr; #print "\tunshifting:\n" and unshift @arr, 'zero'; #print "\tclearing with undef \@arr:\n" and undef @arr; #print "\tSetting list:\n" and @arr = qw(a); #print "\tSetting list:\n" and @arr = qw(a); #print "\tclearing with \@arr=():\n" and @arr=(); #my $ref = \$arr[0]; #print "\tsetting by reference:\n" and $$ref=11; #print "\tclearing:\n" and @arr=();#undef @arr and @arr=undef se +em no good..e # print "\@arr [@arr]\n"; #use Data::Dump;print dd(@arr); [download] thanks L There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l] [select]
Re^4: tie example.. Code still hangs by choroba (Cardinal) on May 01, 2015 at 19:02 UTC
My mistake. The \ before @_ was there because of double quotes, so it should've been removed: `*$_ = sub { &main::trigger; shift()->$s(@_) };` [download] لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re^3: Is tie inteded to be used in this way? Few question arise by Discipulus (Canon) on Apr 29, 2015 at 09:57 UTC
thanks choroba, 1 and 2 ... prove that is not wise to code when you have fever above 38.. i'll try to remember. 3. thanks, now i understand L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l]