Changing the name of a variable in perl , with perl.

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

Hi Guys

Does anyone know how i can get a variable name to be changed depending on what info I pass. I have x number of months depending on the date range the user inserts. (month 1) (month 2) (month 3) etc. These are the column names but i need variables for each month. I want to do this


foreach (@columns) {
  if ($_ =~ /month(\d+)/) {
    $month . $1 = $whatever_value;
  }
}
[download]

If $_ = month4, I want my variable name to be $month4. so, $month4 = whatever_value; Please let me know if you know a solution it would be very much appreciated.

Thanks Bennierounder.

Comment on Changing the name of a variable in perl , with perl. Download Code

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Re: Changin the name of a variable in perl , with perl. by Corion (Patriarch) on Sep 07, 2011 at 08:17 UTC
You don't want to do that. Mark J. Dominus has said it better than I can. The short of it is, use a hash or an array as your data structure instead of using names.	[reply]
Re: Changin the name of a variable in perl , with perl. by Ratazong (Monsignor) on Sep 07, 2011 at 08:46 UTC
`$one = "number_one"; $$one = 1; print ("$number_one\n");` [download] See also yesterdays thread variable constructs that I do not understand. Now that you know that is possible, be aware that this is not what you want. Follow Corions advice and use a hash. Really!	[reply] [d/l]
Re: Changin the name of a variable in perl , with perl. by LanX (Saint) on Sep 07, 2011 at 11:07 UTC
better use either arrays or hashes (depending on the nature of your input): `$month{$1}=$whatever_value; $month[$1]=$whatever_value;` [download] Cheers Rolf	[reply] [d/l]
Re: Changin the name of a variable in perl , with perl. by morgon (Priest) on Sep 07, 2011 at 18:57 UTC
As you've heard don't do it. But you can manipulate the symbol-table to create new variables like this: `no strict "vars"; our $hubba = "whatever"; # create a new variable $bubba and make it an alias for $hubba *{$::{"bubba"}} = \$hubba; print $bubba; # prints "whatever"` [download] Note that this only works for variables that live in the symbol-table ("our"-variables) and not for lexicals (varibles introduced with "my").	[reply] [d/l]