perl - 如何在运行时获取子程序的签名？

Question

Perl 通过 CORE::prototype 提供 API ，这样你就可以得到一个原型(prototype)。 Sub::Util 进一步记录了这一点这是使用潜艇的记录方法，
Sub::Util::prototype ,

Returns the prototype of the given $code reference, if it has one, as a string. This is the same as the CORE::prototype operator; it is included here simply for symmetry and completeness with the other functions.

但是，我没有看到任何关于如何获得 signatures 的信息。在运行时？ perl 是否提供此功能？

Answer 1

这是非常...间接的，但是解析子并解析签名代码。

sub foo ($bar) { return 0 }

use B::Deparse;
$foo = B::Deparse->new->coderef2text(\&foo);

# contents of foo:
# BEGIN {${^WARNING_BITS} = "\x10\x01\x00\x00\x00\x50\x04\x00\x00\x00\x00\x00\x00\x55\x50\x55\x50\x51\x01"}
# use feature 'signatures';
# die sprintf("Too many arguments for subroutine at %s line %d.\n", (caller)[1, 2]) unless @_ <= 1;
# die sprintf("Too few arguments for subroutine at %s line %d.\n", (caller)[1, 2]) unless @_ >= 1;
# my $bar = $_[0];
# return 0;

@foo = split /\n/, $foo;
if ($foo[2] =~ /use feature 'signatures'/ &&
        $foo[3] =~ /Too many arguments/ &&
        $foo[4] =~ /Too few arguments/) {
    @sig = ();
    $n = 5;
    do {
        ($sig) = $foo[$n] =~ /my (\W\w+) = /;
        push @sig,$sig if $sig;
        $n++;
    } while ($sig);
    print "Signature is (", join(",",@sig), ")\n";
}