Your use of do is obviously not wrong. I tend to reserve its use for when I have things I want to pass back out of it. As an example that I use sometimes when I'm in quick and dirty mode:

my $content = do {
    open my $fh, '<', $file or die "Couldn't open $file: $!\n";
    local $/ = undef;
    <$fh>;
};

[download]

Now I don't have to worry about $fh leaking to broader scope, local evaporates at the end of the do, and the contents of the file get returned. It's really just a convenience so I don't have to keep as much state in my head. I could also have done it like this:

my $content;
{
    open my $fh, '<', $file or die "Couldn't open $file: $!\n";
    local $/ = undef;
    $content = <$fh>;
}

[download]

But I prefer using the naked block when I don't need to return something out of it. Another alternative that I occasionally find useful because it lets me make more explicit the passing of information into the construct is the immediate-use lambda expression:

my $content = sub {
    my $file = shift;
    open my $fh, '<', $file or die "Couldn't open $file: $!\n";
    local $/ = undef;
    return <$fh>;
}->($file);

[download]

If do{...} weren't so convenient I think I'd use the throwaway sub a lot more, as a means of limiting scope, and making parameter passing more obvious.

If I use naked blocks to reduce scope it's usually in cases where I don't need to return something. Example:

ok 1;

{
    my $mock = Test::MockModule->new('Foo');
    $mock->redefine(bar => sub {...});

    is baz(10), 42, 'baz gave correct answer to the universe with bar 
+mocked.'
}

ok 3;

[download]

So here there's no intention of returning anything, we just want to constrain our mock to the narrowest scope practical so that we don't forget it's in place and spend two hours trying to figure out why some part of the test 80 lines below is failing in a mysterious way.

Sorry for digressing from the interesting thread's topic of references.


Dave

In reply to Re^6: Pointers and References by davido
in thread Pointers and References by Leudwinus

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • 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! —
  • 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:
    & &amp;
    < &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.