Any way to call GetOptions with evaluated / interpoltated args ?

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

I'd like to call Getopt::Long qw(GetOptions);
where the arguments are built previously.
Here a normal call to GetOptions:

use Getopt::Long qw(GetOptions);
my $arg1;
GetOptions( 'arg1=s' => \$arg1);
[download]

Is there any way to pass the arguments from a previously built scalar/hash/array ?

use Getopt::Long qw(GetOptions);
my arg1;
my $opt = 'arg1=s => \$arg1';
my @opt = ('arg1=s', '\$arg1');
my %opt = ('arg1=s' => '\$arg1');
GetOptions($opt);   #doesn't work  
GetOptions(@opt);   #doesn't work
GetOptions(%opt);   #doesn't work
[download]

I tried different ecaping (i.e. \$, \\$, \\\$),
eval (i.e. eval "GetOptions(...))
eval with explicit global var notation $::arg1
but I cannot have it working.

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Re: Any way to call GetOptions with evaluated / interpoltated args ? by LanX (Saint) on Nov 26, 2018 at 16:15 UTC
variant 2 and 3 should work if you didn't quote the refs... i.e. `\$arg1` instead of `'\$arg1'` Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}	[reply] [d/l] [select]
Re: Any way to call GetOptions with evaluated / interpoltated args ? by Eily (Monsignor) on Nov 26, 2018 at 16:16 UTC
It sounds like an unusual way of doing things, so maybe you should explain the broader context for your question, but to answer it you'll notice that in `GetOptions( 'arg1=s' => \$arg1);` there are no quotes around the second argument. You shouldn't have quotes in your other attempts (ie, instead of sending a string, send a reference): `my @opt = ('arg1=s', \$arg1); my %opt = ('arg1=s' => \$arg1);` [download]	[reply] [d/l] [select]
Re^2: Any way to call GetOptions with evaluated / interpoltated args ? by jjmoka (Beadle) on Nov 26, 2018 at 16:43 UTC
Thank you very much. It works. Here my minor reason to want that. I also know I was entering an unusual field (I would even accept to relax sometimes the 'use strict "refs"' to use symbolic references). My command line script is expected to dump a 'usage' message (with the list of options) and a GetOptions to load them. For my personal taste I didn't like to replicate the same list in the 'usage' message and in GetOptions. I wanted a single list of options and then I'm using that list to both create the message and to feed GetOptions. Thanks again.	[reply]
Re: Any way to call GetOptions with evaluated / interpolated args ? by hippo (Archbishop) on Nov 26, 2018 at 16:41 UTC
You've omitted the sigil when declaring $arg1 - were you not using strict? Here's the trivial example, anyway: `$ cat opts.pl #!/usr/bin/env perl use strict; use warnings; use Getopt::Long 'GetOptions'; my $arg1; my %opt = ('arg1=s' => \$arg1); GetOptions (%opt); print "arg1 is $arg1\n" if defined $arg1; $ ./opts.pl --arg1=foo arg1 is foo $` [download] "It doesn't work" is as useful to a developer as "I'm ill" is to a medic. Try to be specific. SSCCE is best.	[reply] [d/l]
Re: Any way to call GetOptions with evaluated / interpoltated args ? by tinita (Parson) on Nov 26, 2018 at 19:36 UTC
You maybe just want to use Getopt::Long::Descriptive instead, that gives you a usage function for free.	[reply]
Re: Any way to call GetOptions with evaluated / interpoltated args ? by 1nickt (Canon) on Nov 26, 2018 at 16:16 UTC
Hi, one way might be to use Getopt::Long's OO interface. From the doc: `use Getopt::Long; $p = Getopt::Long::Parser->new; $p->configure(...configuration options...); # Do some computing here to come up with list of option descriptio +ns if ($p->getoptions(...options descriptions...)) ... if ($p->getoptionsfromarray( \@array, ...options descriptions...)) + ...` [download] Hope this helps! The way forward always starts with a minimal test.	[reply] [d/l]