Sub::Quote(3)

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

SYNOPSIS
 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

DESCRIPTION
This package provides performant ways to generate subroutines from strings.

SUBROUTINES

  quote_sub
 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. See the "SYNOPSIS"'s "Silly::dagron" for an example using captures.

options

•   no_install

    Boolean. Set this option to not install the generated coderef into the passed subroutine name on undefer.

  unquote_sub
 my $coderef = unquote_sub $sub;

Forcibly replace subroutine with actual code. Note that for performance reasons all quoted subs declared so far will be globally unquoted/parsed in a single eval. This means that if you have a syntax error in one of your quoted subs you may find out when some other sub is unquoted.

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

  quoted_from_sub
 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.

  inlinify
 my $prelude = capture_unroll {
   '$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.

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

Generates a snippet of code which is suitable to be used as a prelude for "inlinify". The keys are the names of the variables and the values are (duh) the values. Note that references work as values.

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

  return
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;
      $morecode
    };
    <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.