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. 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.

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.

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

 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.

  quotify
 my $quoted_value = quotify $value;

Quotes a single (non-reference) scalar value for use in a code string. Numbers aren't treated specially and will be quoted as strings, but undef will quoted as "undef()".

  capture_unroll
 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.

  qsub
 my $hash = {
  coderef => qsub q{ print "hello"; },
  other   => 5,
 };

Arguments: $code

Works exactly like "quote_sub", but includes a prototype to only accept a single parameter. This makes it easier to include in hash structures or lists.

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.

  pragmas
"Sub::Quote" preserves the environment of the code creating the quoted subs. This includes the package, strict, warnings, and any other lexical pragmas. This is done by prefixing the code with a block that sets up a matching environment. When inlining "Sub::Quote" subs, care should be taken that user pragmas won't effect the rest of the code.

SUPPORT
See Moo for support and contact information.

AUTHORS
See Moo for authors.

COPYRIGHT AND LICENSE
See Moo for the copyright and license.