Variable naming of Arrays

stellagoddc has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Variable naming of Arrays by davido (Cardinal) on May 12, 2006 at 15:36 UTC
For all practical purposes, you could live happily with the assumption that it is impossible to do what you're asking. Decades of advances in computer science, and programming languages, have taken us to a point in history where it is virtually unnecessary to do so. And in fact, it actually is impossible in many powerful programming languages. In actuality, Perl will let you tie yourself a noose. Perl will let you use "symbolic references" (which is what you're asking about). But until you have a thorough understanding of why not, you just shouldn't, and you probably don't need to. The stock answer for this sort of question is to use a hash. Perl's package global variables reside in a glorified hash. If a hash is good enough for Perl, it should be good enough for your purposes too. `my %arrays; $arrays{bart} = [ 1, 2, 3, 4, 5 ]; $arrays{homer} = [ 80, 42, 33, 51, 0 ]; print $arrays{homer}[3], "\n";` [download] See how easy it is to do the right thing? ;) Dave	[reply] [d/l]
Re^2: Variable naming of Arrays by stellagoddc (Novice) on May 12, 2006 at 16:08 UTC
Thanks a lot. I dont suppose you can use 'push' with hashes as well? something like `$arrays{bart} = [ 1, 2, 3 ]; push ($arrays{bart}, [ 4, 5 ];` [download] Thanks	[reply] [d/l]
Re^3: Variable naming of Arrays by davorg (Chancellor) on May 12, 2006 at 16:14 UTC
You can't use push with a hash. But you can use push with an array reference if you dereference it first. `$arrays{bart} = [ 1, 2, 3 ]; push @{$arrays{bart}}, 4, 5;` [download] -- <http://dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply] [d/l]
Re: Variable naming of Arrays by Fletch (Bishop) on May 12, 2006 at 15:25 UTC
Yes, but you don't really want to. What you want is a data structure using references (your example would be a hash of arrays, or HoA). See `perldoc perlreftut` and `perldoc perllol`.	[reply]
Re^2: Variable naming of Arrays by stellagoddc (Novice) on May 12, 2006 at 15:31 UTC
Thanks	[reply]
Re: Variable naming of Arrays by tinita (Parson) on May 13, 2006 at 14:38 UTC
now, imagine, what should happen if a string in the file is "ARGV" or INC", for example? others in this thread have given you enough pointers for alternatives.	[reply]
Re: Variable naming of Arrays by blazar (Canon) on May 12, 2006 at 15:51 UTC
Yes. It gets asked once a day (if not here in other forums or newsgroups). And it gets answered all the time that you don't really want to. What you "want" is called a symref and is not permitted under strict. Read about real references instead!	[reply]
Re: Variable naming of Arrays by TedPride (Priest) on May 12, 2006 at 19:10 UTC
What if the number of strings is not divisible by 10? Which string is going to be the name of the array? The following does what you want, only using the first string of every 10, not the last: `chomp (@_ = <DATA>); for ($_ = 0; $_ <= $#_; $_ += 10) { @{$_[$_]} = @_[($_+1)..($_+9)]; } print "@alpha"; __DATA__ alpha beta gamma delta epsilon zeta eta theta iota kappa lamda mu nu` [download] DISCLAIMER: YOU SHOULD NEVER USE CODE LIKE THIS. Proper code would be more like the following: `use strict; use warnings; my (@arr, %find, @order, $i); chomp (@arr = <DATA>); for ($i = 0; $i <= $#arr; $i += 10) { $find{$arr[$i]} = [@arr[($i+1)..($i+9)]]; push @order, $arr[$i]; } { no warnings; print "@{$find{$_}}\n" for @order; } __DATA__ alpha beta gamma delta epsilon zeta eta theta iota kappa lamda mu nu` [download]	[reply] [d/l] [select]