I generally consider it to be cargo cult. There's no situation where require lives but returns false.

That said, your case 3 is incorrect. Require doesn't (always) return "1". It returns whatever the module returned.

$ cat Foo.pm 
package Foo;
2;
$ perl -E'say eval "require Foo"'
2

[download]

Case 3b is correct though - if a module has already been loaded, require just returns 1.

$ perl -E'say eval "require Foo" for 1..3'
2
1
1

[download]
use Moops; class Cow :rw { has name => (default => 'Ermintrude') }; say Cow->new->name

In reply to Re: The 'eval "require $module; 1"' idiom by tobyink
in thread The 'eval "require $module; 1"' idiom by sedusedan

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