Sub::Quote(3) User Contributed Perl Documentation Sub::Quote(3)NAMESub::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
ยท 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.
perl v5.16.2 2012-07-04 Sub::Quote(3)
