perl - 使用 Perl，如何跟踪常量被重新定义的位置？

Question

我正在使用 perl。我不断收到这些错误

Constant subroutine Samp::foo redefined at /usr/local/share/perl/5.20.2/constant.pm
Constant subroutine Samp::bar redefined at /usr/local/share/perl/5.20.2/constant.pm 
Constant subroutine Samp::baz redefined at /usr/local/share/perl/5.20.2/constant.pm

我如何追踪重新定义它们的因素。使用强力方法，我能够通过从 use base qw/quz qaz/ 到 use base 'qaz' 中删除复合语句一次来抑制此错误。我认为这表明我遇到了其他一些错误。如果您知道如何添加此调试代码，我可以破解 constant.pm。

如果有一个 Devel:: 模块可以帮助我，或者有一个替代的工作流来解决这个问题，也会支持。

问题好像是documented here .

Answer 1

我建议使用 Carp 库。

这是一个最小的例子:

Foo.pm

package Foo;

use Exporter 'import';
@EXPORT_OK = qw( abc );

use constant abc => 123;
1;

foo.pl

#!/usr/bin/env perl

use strict;
use warnings;

use Foo qw( abc );
use Carp;
$Carp::Verbose = 1;
$Carp::CarpLevel = 2;
$SIG{__WARN__} = sub { carp(@_) };

print "Before redefine\n";
eval "use constant abc => 456;";
print "After redefine\n";

perl foo.pl

Before redefine
Constant subroutine main::abc redefined at /usr/share/perl5/vendor_perl/constant.pm line 140.
at (eval 1) line 1.
    main::BEGIN() called at (eval 1) line 1
    eval {...} called at (eval 1) line 1
    eval 'use constant abc => 456;' called at foo.pl line 13
After redefine