| true(3pm) | User Contributed Perl Documentation | true(3pm) |
true - automatically return a true value when a file is required
package Contemporary::Perl;
use strict;
use warnings;
use true;
sub import {
strict->import();
warnings->import();
true->import();
}
Perl's "require" builtin (and its "use" wrapper) requires the files it loads to return a true value. This is usually accomplished by placing a single
1;
statement at the end of included scripts or modules. It's not onerous to add but it's a speed bump on the Perl novice's road to enlightenment. In addition, it appears to be a non-sequitur to the uninitiated, leading some to attempt to mitigate its appearance with a comment:
1; # keep require happy
or:
1; # Do not remove this line
or even:
1; # Must end with this, because Perl is bogus.
This module packages this "return true" behaviour so that it doesn't need to be written explicitly. It can be used directly, but it is intended to be invoked from the "import" method of a Modern::Perl-style module that enables modern Perl features and conveniences and cleans up legacy Perl warts.
"true" is file-scoped rather than lexically-scoped. Importing it anywhere in a file (e.g. at the top-level or in a nested scope) causes that file to return true, and unimporting it anywhere in a file restores the default behaviour. Redundant imports/unimports are ignored.
import
Enable the "automatically return true" behaviour for the currently-compiling file. This should typically be invoked from the "import" method of a module that loads "true". Code that uses this module solely on behalf of its callers can load "true" without importing it e.g.
use true (); # don't import
sub import {
true->import();
}
1;
But there's nothing stopping a wrapper module also importing "true" to obviate its own need to explicitly return a true value:
use true; # both load and import it
sub import {
true->import();
}
# no need to return true
unimport
Disable the "automatically return true" behaviour for the currently-compiling file.
None by default.
Because the unquoted name "true" represents the boolean value "true" in YAML, the module name must be quoted when written as a dependency in META.yml. In cases where this can't easily be done, a dependency can be declared on the package true::VERSION, which has the same version as "true.pm".
1.0.2
chocolateboy <chocolate@cpan.org>
Copyright (c) 2010-2020 by chocolateboy.
This library is free software; you can redistribute it and/or modify it under the terms of the Artistic License 2.0 <https://www.opensource.org/licenses/artistic-license-2.0.php>.
| 2022-10-21 | perl v5.36.0 |