phpman > perldoc > Sub::Defer(3pm)

NAME
    Sub::Defer - Defer generation of subroutines until they are first called

SYNOPSIS
     use Sub::Defer;

     my $deferred = defer_sub 'Logger::time_since_first_log' => sub {
        my $t = time;
        sub { time - $t };
     };

      Logger->time_since_first_log; # returns 0 and replaces itself
      Logger->time_since_first_log; # returns time - $t

DESCRIPTION
    These subroutines provide the user with a convenient way to defer creation of subroutines and
    methods until they are first called.

SUBROUTINES
  defer_sub
     my $coderef = defer_sub $name => sub { ... }, \%options;

    This subroutine returns a coderef that encapsulates the provided sub - when it is first called,
    the provided sub is called and is -itself- expected to return a subroutine which will be goto'ed
    to on subsequent calls.

    If a name is provided, this also installs the sub as that name - and when the subroutine is
    undeferred will re-install the final version for speed.

    Exported by default.

   Options
    A hashref of options can optionally be specified.

    package
        The package to generate the sub in. Will be overridden by a fully qualified $name option. If
        not specified, will default to the caller's package.

    attributes
        The "Subroutine Attributes" in perlsub to apply to the sub generated. Should be specified as
        an array reference.

  undefer_sub
     my $coderef = undefer_sub \&Foo::name;

    If the passed coderef has been deferred this will "undefer" it. If the passed coderef has not
    been deferred, this will just return it.

    If this is confusing, take a look at the example in the "SYNOPSIS".

    Exported by default.

  defer_info
     my $data = defer_info $sub;
     my ($name, $generator, $options, $undeferred_sub) = @$data;

    Returns original arguments to defer_sub, plus the undeferred version if this sub has already
    been undeferred.

    Note that $sub can be either the original deferred version or the undeferred version for
    convenience.

    Not exported by default.

  undefer_all
     undefer_all();

    This will undefer all deferred subs in one go. This can be very useful in a forking environment
    where child processes would each have to undefer the same subs. By calling this just before you
    start forking children you can undefer all currently deferred subs in the parent so that the
    children do not have to do it. Note this may bake the behavior of some subs that were intended
    to calculate their behavior later, so it shouldn't be used midway through a module load or class
    definition.

    Exported by default.

  undefer_package
      undefer_package($package);

    This undefers all deferred subs in a package.

    Not exported by default.

SUPPORT
    See Sub::Quote for support and contact information.

AUTHORS
    See Sub::Quote for authors.

COPYRIGHT AND LICENSE
    See Sub::Quote for the copyright and license.