I would much agree on the remarks made by other monks, to use a hash for your config vars is a much cleaner and safer approach.
Having said that, your idea of using an eval can work as per below example. Just keep in mind that:
- eval runs as a nested block, therefore any variables declared within eval are lost once eval is done. Hence you you need to declare your variables before using them in the eval.
- make sure that your eval cannot be abused thru evil data in a configfile. So check all input before you use it in eval, make sure to single-quote string so that they do not get interpreted, etc etc.
#!/usr/bin/perl
use warnings;
use strict;
my @accepted_vars = qw( myvar1 myvar2 );
my $myvar1; # must declare variable beforehand!
my $myvar2;
my @lines = <DATA>;
chomp @lines;
foreach (@lines) {
if ( /^\s*(.*?)\s*=\s*(.*)/ &&
grep $1 eq $_ , @accepted_vars
) {
eval '$'."$1 = '$2'";
warn "eval failed: $@\n" if $@;
}
else {
warn "Illegal config var '$1'\n";
}
}
print "myvar1 = '$myvar1'\n",
"myvar2 = '$myvar2'\n";
__DATA__
myvar1 = foo
myvar2 = bar
evil_var = foo
Output from program is:
Illegal config var 'evil_var'
myvar1 = 'foo'
myvar2 = 'bar'