Hello, Monks,

I'm looking for a module to extract words from a stream of text. I installed Text::ExtractWords and tried it: 

#!/usr/bin/env perl
use v5.38;
use Text::ExtractWords qw(words_list);
say $^V;
my $text = "12/21/84 Bob's 21st b'day was a wine-and-dine.";
say $text;
my @list;
words_list(\@list, $text, {minwordlen => 2, maxwordlen => 26 });
say "Found words: " . join ' ', map {"[$_]"} @list;
say $text;

[download]
v5.38.2
12/21/84 Bob's 21st b'day was a wine-and-dine.
Found words: [12] [21] [84] [bob's] [21st] [b'day] [was] [a] [wine-and
+-dine]
122184bob's21stb'daywasawine-and-dine

[download]
Note the output value of $text after call. How is it possible for any subroutine to modify a parameter, since I don't pass in a reference?

Moreover, I looked at Text::ExtractWords.pm and it's all basically boilerplate except maybe for one line, which I don't understand: 

bootstrap Text::ExtractWords $VERSION;

[download]
I feel like I'm missing something obvious here...

Update: I'm not able to step into words_list() using the debugger! It just proceeds to my next source line.

Update2: I even tried making a copy of $text (my $copy = $text) and passing $copy to words_list(), and afterwards *both* $copy and $text were munged. As Danny mentions below, this is XS code.

In reply to Text::ExtractWords exhibits incomprehensible behavior? by ibm1620

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