sub begin_work {
    use Data::Dumper;

    ... lotsa code

    no Data::Dumper;
    return;
}
[download]

This doesn't address your immediate problem, but application code modules like Data::Dumper do not follow the lexical scoping rules that pragma modules like strict, warnings and integer follow.

The effects of the use Data::Dumper; statement are seen from the point in the file at which the module is use-ed at compile time and in all code beyond that point.

Win8 Strawberry 5.8.9.5 (32)  Sun 01/10/2021 10:52:26
C:\@Work\Perl\monks
>perl -Mstrict -Mwarnings
# pm#11126693

foo();  # try disabling this statement

print Dumper [ qw(1 2 3) ];  # print() on unopened filehandle Dumper

# foo();  # try enabling this statement

sub foo {
    use Data::Dumper;
    print Dumper [ qw(a b c) ];

    no Data::Dumper;  # has no effect
    print Dumper [ qw(x y z) ];
    }

print Dumper [ qw(9 8 7) ];  # prints as expected
^Z
$VAR1 = [
          'a',
          'b',
          'c'
        ];
$VAR1 = [
          'x',
          'y',
          'z'
        ];
print() on unopened filehandle Dumper at - line 5.
$VAR1 = [
          '9',
          '8',
          '7'
        ];
[download]

Same results running under Perl version 5.30.3.1.

Update: Another little twist to consider is the effect of adding a declaration of the Dumper subroutine in the main package before the first call to Dumper (and before the use Data::Dumper; statement):

sub Dumper;

print Dumper [ qw(1 2 3) ];  # print() on unopened filehandle Dumper
[download]

What happens and why? Is there another way to identify Dumper to the compiler as a subroutine? What would happen if one wrote:

### sub Dumper;

print Dumper([ qw(1 2 3) ]);  # print() on unopened filehandle Dumper
[download]

(I see the same results under both versions 5.8.9 and 5.30.3.)

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.