Matt S Trout > Moo-1.003001 > Sub::Quote



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Module Version: 1.003001   Source   Latest Release: Moo-1.004_003


Sub::Quote - efficient generation of subroutines via string eval


 package Silly;

 use Sub::Quote qw(quote_sub unquote_sub quoted_from_sub);

 quote_sub 'Silly::kitty', q{ print "meow" };

 quote_sub 'Silly::doggy', q{ print "woof" };

 my $sound = 0;

 quote_sub 'Silly::dagron',
   q{ print ++$sound % 2 ? 'burninate' : 'roar' },
   { '$sound' => \$sound };

And elsewhere:

 Silly->kitty;  # meow
 Silly->doggy;  # woof
 Silly->dagron; # burninate
 Silly->dagron; # roar
 Silly->dagron; # burninate


This package provides performant ways to generate subroutines from strings.



 my $coderef = quote_sub 'Foo::bar', q{ print $x++ . "\n" }, { '$x' => \0 };

Arguments: ?$name, $code, ?\%captures, ?\%options

$name is the subroutine where the coderef will be installed.

$code is a string that will be turned into code.

\%captures is a hashref of variables that will be made available to the code. The keys should be the full name of the variable to be made available, including the sigil. The values should be references to the values. The variables will contain copies of the values. See the "SYNOPSIS"'s Silly::dagron for an example using captures.



 my $coderef = unquote_sub $sub;

Forcibly replace subroutine with actual code.

If $sub is not a quoted sub, this is a no-op.


 my $data = quoted_from_sub $sub;

 my ($name, $code, $captures, $compiled_sub) = @$data;

Returns original arguments to quote_sub, plus the compiled version if this sub has already been unquoted.

Note that $sub can be either the original quoted version or the compiled version for convenience.


 my $prelude = capture_unroll '$captures', {
   '$x' => 1,
   '$y' => 2,

 my $inlined_code = inlinify q{
   my ($x, $y) = @_;

   print $x + $y . "\n";
 }, '$x, $y', $prelude;

Takes a string of code, a string of arguments, a string of code which acts as a "prelude", and a Boolean representing whether or not to localize the arguments.


 my $prelude = capture_unroll '$captures', {
   '$x' => 1,
   '$y' => 2,
 }, 4;

Arguments: $from, \%captures, $indent

Generates a snippet of code which is suitable to be used as a prelude for "inlinify". $from is a string will be used as a hashref in the resulting code. The keys of %captures are the names of the variables and the values are ignored. $indent is the number of spaces to indent the result by.


Much of this is just string-based code-generation, and as a result, a few caveats apply.


Calling return from a quote_sub'ed sub will not likely do what you intend. Instead of returning from the code you defined in quote_sub, it will return from the overall function it is composited into.

So when you pass in:

   quote_sub q{  return 1 if $condition; $morecode }

It might turn up in the intended context as follows:

  sub foo {

    <important code a>
    do {
      return 1 if $condition;
    <important code b>


Which will obviously return from foo, when all you meant to do was return from the code context in quote_sub and proceed with running important code b.


Sub::Quote compiles quoted subs in an environment where use strictures is in effect. strictures enables strict and FATAL warnings.

The following dies Use of uninitialized value in print...

 no warnings;
 quote_sub 'Silly::kitty', q{ print undef };

If you need to disable parts of strictures, do it within the quoted sub:

 quote_sub 'Silly::kitty', q{ no warnings; print undef };


See Moo for support and contact information.


See Moo for authors.


See Moo for the copyright and license.

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