如何在运行时获取子程序的签名？

Question

Perl 通过 CORE::prototype 提供了 API，它允许您获得原型。 Sub::Util 进一步记录了这是使用 subs 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，我在任何地方都看不到有关如何在运行时获取 signatures 的信息？ Perl 是否提供此功能？

Answer 1

来自 irc.freenode.net/#perl,

15:03 < Grinnz> there's no perl level api for that

这几乎是一个 perl 小高手。他向我指出了 this work from Nov 2019，它开始沿着“签名内省 API”的路径前进。“

Answer 2

目前这是不可能的，原因与传统参数解析 (my ($foo, $bar) = @_;) 不可能的原因相同：它在子例程内部。

之前有人建议添加这样的东西，但目前看来不太可能。

Answer 3

这很...间接，但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";
}

如何在运行时获取子程序的签名？

How do I get the signature of a subroutine in runtime?

perl

metaprogramming

signature

subroutine

subroutine-prototypes