Re: (tye)Re: change 'use constant' value through commandline arguments?

Here is what I did come up with through the education/help received in this thread:

# set debugging switch to OFF
my $debug_switch = 0;

# go through the argument evaluation at compile time
BEGIN
{
    # check each argument
    foreach $_ (@ARGV)
    {
        # is the debug switch submitted?
        if (/^-d$/i)
        {
            # yup. set debugging switch to ON
            $debug_switch = 1;
        }
    }
}
# set DEBUGGING to the debug_switch value
use constant DEBUGGING => $debug_switch;
[download]

It works, doesn't throw any warnings, and I use a constant like it is normally done: Define once, use x times.

Comment on Re: (tye)Re: change 'use constant' value through commandline arguments? Download Code

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Re: Re: Re: change 'use constant' value through commandline arguments? by Kanji (Parson) on Mar 15, 2002 at 01:27 UTC
Rather than just setting it to `1`, it may be more flexible to use `$debug_switch++` instead; that way you could increase the debug level with every `-d` on the command-line, letting you do things like... `use constant VAGUE => 0; use constant DETAILED => 1; use constant PEDANTIC => 2; if ( @x ) { warn( "\@x is set\n" ) if DEBUG > VAGUE; warn( scalar(@x)," elements\n" ) if DEBUG > DETAILED; { local $" = "\n "; warn( "They are...\n @x\n" ) if DEBUG > PEDANTIC; } }` [download] Lame example, but hopefully you get the point... `:)` --k.	[reply] [d/l]
Re: Re: (tye)Re: change 'use constant' value through commandline arguments? by blakem (Monsignor) on Mar 14, 2002 at 23:45 UTC
tye's original suggestion can easilly be modified to use 1/0 instead of -d/undef for TRUE/FALSE values.... is that why you opted for his second (longer) suggestion? `use constant DEBUGGING => (grep $_ eq "-d", @ARGV) ? 1 : 0;` [download] -Blake	[reply] [d/l]
Rex3: (tye) change 'use constant' value through commandline arguments? by Sweeper (Pilgrim) on Mar 15, 2002 at 06:50 UTC
Would not it be easier just to code use Getopt::Long; GetOptions("debug" => \$debug_switch); or even use Getopt::Long; GetOptions("debug+" => \$debug_switch); which allows several levels of debugging.	[reply]
Re: Rex3: (tye) change 'use constant' value through commandline arguments? by neuroball (Pilgrim) on Mar 15, 2002 at 18:52 UTC
It might be easier... but it is shorter. Btw. In my 'solution' above I made a mistake that I just found as I was porting the script from my IDE (Komodo) to the server. The undefined constant (debugging turned off) throws warnings about void constants. To get around this I used the following short fix: `# set DEBUGGING to the debug_switch value use constant DEBUGGING => $debug_switch \|\| 0;` [download] Now to answer some questions... Q: 'Why did I opt for the long version?' A: It is clear and maintainable, even by persons with a minimum perl knowledge. I do this just to be nice to the people who have to live with my code. Q: 'Why not use more than one level of debugging messages?' A: I didn't need more than one. And knowing the application I doubt very much that this will change. But... if I ever in need to use more than on level of debugging I will sure come back to this thread and look at the offered solutions for this feature. thx /oliver	[reply] [d/l]