#!/usr/bin/perl
use strict;
use warnings;
use 5.012;
# 927943
#  process to run "continuously" from command prompt unless and until I want to enter something...

say "\n\t Enter 'i' or 'I' followed by <CR> or <CR> (only) to interupt;\n\t any other char to continue";

my $NOP = "NoInterupt";
my $i = 1;

sub continuous
{
	my $continuous = 1;
LABEL:  $continuous += $i;
		$i++;
		say $continuous;
		# sleep 1;
		if ($continuous >= 25 ) {
			say "continuous >= 25, several iterations completed";
			return;
		}
		goto LABEL unless ( $NOP ne "NoInterupt") ;
}

sub T
{
	say "this is from sub T (which ain't doing much, but could be used to deal with an operator input...";
	say "for example, try 'R' next time";
	return;
}

sub R
{
	say "About to \"R\" ('run some code')... ";
	my @foo = qw/foo bar undef 123/;
	for my $foo(@foo) { 
		say "\t $foo";
	}
	return;
}

# MAIN

START: continuous();
chomp ( my $interupt = <> );
if ( $interupt =~ /[A-H]|[J-Q]|S|[U-Z]/i ) {
	$NOP = "NoInterupt";
	goto START;                        
} elsif ( $interupt =~/r/i ) {
	R();
	$NOP = "R";
	goto START;                               
} elsif ( $interupt =~/t/i ) {
	T();
	$NOP="T";
	goto START;           
} elsif ( ($interupt =~/i/i) || ($interupt =~ /''/)) {         # exactly 'i' or 'I' or no entry
	$NOP = "\tSCRAM the reactor!";
	say "$NOP, \$i: $i";
}


=head execution and output:

C:\>927943.pl

         Enter 'i' or 'I' followed by <CR> or <CR> (only) to interupt;
         any other char to continue
2
4
7
11
16
22
29
continuous >= 25, several iterations completed
l
9
18
28
continuous >= 25, several iterations completed
r
About to "R" ('run some code')...
         foo
         bar
         undef
         123
12
s
13
26
continuous >= 25, several iterations completed
t
this is from sub T (which ain't doing much, but could be used to deal with an operator input...
for example, try 'R' next time
15
u
16
32
continuous >= 25, several iterations completed
i
        SCRAM the reactor!, $i: 17

C:\>

=cut