Re: How can I use printf FORMAT strings for (Win32) shell globs?

Though I am far from a regex expert, I had a thought that I hadn't seen suggested yet: watching you use the first regex to extract $prefix, and then a second to extract $format from $prefix, you could actually combine the two extractions into the same regex: with nested parentheses, the arguments are assigned in the left-to-right order of the open-parenthesis (see perlretut#Extracting matches). Using this, plus stevieb's and kcott's excellent suggestions, my regex snippet would be:

use warnings;
use strict;
...
my ($prefix, $format, $count, $ext) = ($match =~ /(\w+)(%(\d+)d)\.(\w+
+)/) or die "cannot find match";   # EX: Img%04d.png
printf("  \$prefix: >%s<\n", $prefix);      # (\w+)     => Img
printf("  \$format: >%s<\n", $format);      # (%...d)   => %04d
printf("   \$count: >%s<\n", $count);       # (\d+)     => 04
printf("     \$ext: >%s<\n\n", $ext);       # (\w+)     => png
...
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Re^2: How can I use printf FORMAT strings for (Win32) shell globs? by AnomalousMonk (Archbishop) on Jul 17, 2017 at 15:29 UTC
One can elaborate on this. Surely, the `%` and `d` parts are pointless to extract: if anything is extracted, you know it's a format and you know it's a `d` format. The leading `0` on the `04` tells you zero versus space lead-padding in an integer format specifier, but padding with spaces in a file name seems a bit dodgy, so you're really only concerned with whether the width is true/false "fixed and leading-zero padded". (Update: Well, if it's never space-padded, I guess the `0` is superfluous and you don't have to worry about it at all: if a width is given, it's fixed!) `c:\@Work\Perl\monks>perl -wMstrict -le "my $string = 'Img%04d.png'; ;; my $d_format = my ($prefix, $fixed, $width, $ext) = $string =~ m{ \A (\w+) % (0?) (\d+) d [.] (\w+) \z }xms; ;; die 'no format' unless $d_format; $fixed = length $fixed ? 1 : ''; ;; print qq{string: '$string'}; print qq{prefix: '$prefix'}; print qq{ fixed: '$fixed'}; print qq{ width: '$width'}; print qq{ ext: '$ext'}; " string: 'Img%04d.png' prefix: 'Img' fixed: '1' width: '4' ext: 'png'` [download] One can imagine extending this approach to the `%s` format with various min/max widths, justification, etc. Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]

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Re^2: How can I use printf FORMAT strings for (Win32) shell globs?
by AnomalousMonk (Archbishop) on Jul 17, 2017 at 15:29 UTC

One can elaborate on this. Surely, the % and d parts are pointless to extract: if anything is extracted, you know it's a format and you know it's a d format. The leading 0 on the 04 tells you zero versus space lead-padding in an integer format specifier, but padding with spaces in a file name seems a bit dodgy, so you're really only concerned with whether the width is true/false "fixed and leading-zero padded". (Update: Well, if it's never space-padded, I guess the 0 is superfluous and you don't have to worry about it at all: if a width is given, it's fixed!)

c:\@Work\Perl\monks>perl -wMstrict -le
"my $string = 'Img%04d.png';
 ;;
 my $d_format =
 my ($prefix, $fixed, $width, $ext) =
 $string =~ m{ \A (\w+) % (0?) (\d+) d [.] (\w+) \z }xms;
 ;;
 die 'no format' unless $d_format;
 $fixed = length $fixed ? 1 : '';
 ;;
 print qq{string: '$string'};
 print qq{prefix: '$prefix'};
 print qq{ fixed: '$fixed'};
 print qq{ width: '$width'};
 print qq{   ext: '$ext'};
"
string: 'Img%04d.png'
prefix: 'Img'
 fixed: '1'
 width: '4'
   ext: 'png'
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