Perl 如何检测导出的SUB覆盖?
具有下一个代码:Perl 如何检测导出的SUB覆盖?,perl,Perl,具有下一个代码: use strict; use warnings; use Devel::Peek; use YAML; my $s = {a=>'b'}; print Dump($s); 它打印YAML输出: --- a: b 现在更改模块的顺序 use strict; use warnings; use YAML; use Devel::Peek; my $s = {a=>'b'}; print Dump($s); 它打印: SV = IV(0x7ff5d2829
use strict;
use warnings;
use Devel::Peek;
use YAML;
my $s = {a=>'b'};
print Dump($s);
它打印YAML输出:
---
a: b
现在更改模块的顺序
use strict;
use warnings;
use YAML;
use Devel::Peek;
my $s = {a=>'b'};
print Dump($s);
它打印:
SV = IV(0x7ff5d2829308) at 0x7ff5d2829318
REFCNT = 1
FLAGS = (PADMY,ROK)
RV = 0x7ff5d2803438
SV = PVHV(0x7ff5d2808d20) at 0x7ff5d2803438
REFCNT = 1
FLAGS = (SHAREKEYS)
ARRAY = 0x7ff5d243acf0 (0:7, 1:1)
hash quality = 100.0%
KEYS = 1
FILL = 1
MAX = 7
Elt "a" HASH = 0x274d838f
SV = PV(0x7ff5d2804070) at 0x7ff5d2828a00
REFCNT = 1
FLAGS = (POK,IsCOW,pPOK)
PV = 0x7ff5d240e2d0 "b"\0
CUR = 1
LEN = 16
COW_REFCNT = 1
Use of uninitialized value in print at yy line 8.
两个模块都导出一个函数Dump
,因此最后一个模块获胜
我已经启用了
警告
,但它没有就导出的函数重新定义(覆盖?)向我发出警告。可以检测并显示此类重新定义的警告?最有趣的问题。我认为问题在于Exporter.pm没有启用警告。下面是一组简单的文件,演示了您描述的行为:
下午六时
package Foo;
use base 'Exporter';
our @EXPORT = qw(Baz);
sub Baz {
print "Hello from Foo::Baz\n";
}
下午六时三十分
package Bar;
use base 'Exporter';
our @EXPORT = qw(Baz);
sub Baz {
print "Hi from Bar::Baz\n";
}
import-redefine.pl:
use strict;
use warnings;
use Foo;
use Bar;
Baz();
样本运行:
C:\Users\Lona\Desktop\pm>perl import-redefine.pl
Hi from Bar::Baz
颠倒use
语句,如下所示:
use strict;
use warnings;
use Bar;
use Foo;
Baz();
然后再次运行:
C:\Users\Lona\Desktop\pm>perl import-redefine.pl
Hello from Foo::Baz
我提出了以下解决方案,重新定义了Exporter.pm的默认import
方法:
BEGIN {
require Exporter; # We'll need Exporter.pm loaded.
my $old_import = \&Exporter::import; # Save copy of original Exporter::import.
no strict 'refs'; # We'll be using some hacks that will
no warnings 'redefine'; # raise errors and warnings. Suppress those.
*Exporter::import = sub { # Our enhancement of Exporter::import.
use Carp;
my $pkg = shift;
my $callpkg = caller($Exporter::ExportLevel + 1);
my @exports = @_ > 0 # Which subs to export?
? @_ # Those provided as 'use MODULE' arguments...
: @{"$pkg\::EXPORT"} # Or thosedefined in the module's @EXPORT?
;
foreach my $sub (@exports) { # For each of the exportees...
if (exists ${"$callpkg\::"}{$sub}) { # ... check if it exists...
carp "Subroutine $callpkg\::$sub redefined by import"; # and throw a warning if needed.
}
$old_import->($pkg, @_); # Call the original Exporter::import.
}
}
}
要使用它,但它位于主脚本文件中use MODULE
语句上方的某个位置:
use strict;
use warnings;
BEGIN {
require Exporter; # We'll need Exporter.pm loaded.
my $old_import = \&Exporter::import; # Save copy of original Exporter::import.
no strict 'refs'; # We'll be using some hacks that will
no warnings 'redefine'; # raise errors and warnings. Suppress those.
*Exporter::import = sub { # Our enhancement of Exporter::import.
use Carp;
my $pkg = shift;
my $callpkg = caller($Exporter::ExportLevel + 1);
my @exports = @_ > 0 # Which subs to export?
? @_ # Those provided as 'use MODULE' arguments...
: @{"$pkg\::EXPORT"} # Or thosedefined in the module's @EXPORT?
;
foreach my $sub (@exports) { # For each of the exportees...
if (exists ${"$callpkg\::"}{$sub}) { # ... check if it exists...
carp "Subroutine $callpkg\::$sub redefined by import"; # and throw a warning if needed.
}
$old_import->($pkg, @_); # Call the original Exporter::import.
}
}
}
use Foo;
use Bar;
Baz();
然后运行它:
C:\Users\Lona\Desktop\pm>perl import-redefine.pl
Subroutine main::Baz redefined by import at import-redefine.pl line 21.
main::__ANON__("Bar") called at import-redefine.pl line 30
main::BEGIN() called at import-redefine.pl line 30
eval {...} called at import-redefine.pl line 30
Hi from Bar::Baz
哇-很好的详细答案。老实说,希望在一些更容易的事情上,比如
使用warnins“exported_functions”或soo,但这似乎不是一件容易的事情。非常感谢。