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Manual Reference Pages  -  SUB::QUOTE (3)

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NAME

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

CONTENTS

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
o no_install

<B>BooleanB>. 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 <B>BooleanB> 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.
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