simple substitution

megaurav2002 has asked for the wisdom of the Perl Monks concerning the following question:

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Re: simple substitution by lidden (Curate) on Nov 02, 2007 at 05:24 UTC
`use constant UPPER_LIMIT => 10;`	[reply] [d/l]
Re^2: simple substitution by megaurav2002 (Monk) on Nov 02, 2007 at 05:35 UTC
Thanks for the help!	[reply]
Re: simple substitution by narainhere (Monk) on Nov 02, 2007 at 06:28 UTC
if you are defining "UPPER_LIMIT" for a single script then `use constant UPPER_LIMIT => 10;` [download] as suggested by lidden will be fine.If you want to scale up and use the same constant in multiple scripts then you can define the constant (and all common VARS that you scripts) in a file and require that file in you scripts! To illustrate this type the following `$UPPER_LIMIT=10; 1;` [download] in a file called "ENV.pl"(Please note the 1 thats returned in last line), then in you scripts use `require "ENV.pl";` [download] This will import the contents of ENV.pl The world is so big for any individual to conquer	[reply] [d/l] [select]
Re^2: simple substitution by ikegami (Patriarch) on Nov 02, 2007 at 06:32 UTC
Using `require` to load a file without a `package` statement is asking for trouble. Use `do` for such files. Better yet if you're going for re-use, make a real module (one that uses `package`) and use Exporter or the like to allow the user code to import only the constants and variables it needs.	[reply] [d/l] [select]
Re: simple substitution by tuxz0r (Pilgrim) on Nov 02, 2007 at 15:13 UTC
A couple other ways to do this (depending on your goals and needs) would be to use `Readonly` instead of `use constant`, which is less prone to problems like having your constants considered "bare words" in string interpolation, hash keys and the like. So, you might use: `use Readonly; Readonly my $UPPERLIMIT => 10; ...` [download] And, though I think I'm the only one who's ever used this feature, `perl` has the `-P` option which will actually pass your script through the C preprocessor before interpreting and running. In that case, you could just use `#define` for constants just like in C and C++. But, that wouldn't be very 'perlish', would it. These may not be what you need (especially the `-P` option), but I do like `Readonly` a little better than `use constant`. --- echo S 1 [ Y V U \| perl -ane 'print reverse map { $_ = chr(ord($_)-1) } @F;'	[reply] [d/l]

The world is so big for any individual to conquer