打印Perl对象方法的地址? (用于重新定义Perl类方法) [英] Printing addresses of Perl object methods? (for redefining Perl class methods)
问题描述
我看到了如何重新定义Perl类方法?,所以我想通过一个例子更好地了解它的工作原理. (相关:如何引用方法?-PerlMonks )
如果我有一个对象$obj
,它是具有Class::method
的某些Class
的实例,那么$obj
也具有$obj->method
;我认为在这种情况下,简化的内存布局将看起来像这样(在 LaTeX表生成器中创建的表;对于以下内容,请此处为src ):
...即在(说)地址0x1000处有$obj->method
,它只是(以某种方式)指向实际的Class::method
定义,即(说)在0x3500.
比方说,那么我在主文件中的某个位置somefunc
(忽略表中的前缀$)定义了sub
,其定义最终位于地址0x2000.
如果我仅对 奇怪的是,即使在主文件 因此,我显然没有打印我认为是函数地址的内容-而且我认为,每个调用有两个打印输出,而我应该只有一个打印输出,这一事实也得到了证实. 如何更改以下代码,以便打印出可以帮助我确认补丁/重载按预期发生的地址? 这是代码,
对象没有方法.类.一个对象只是一个变量,带有与之关联的包. 所以真正的布局是 更改程序包会影响使用该程序包的所有对象. I saw How can I redefine Perl class methods?, so I wanted to understand better how it works through an example. (Related: How do I reference methods? - PerlMonks) If I have an object ... that is, at (say) address 0x1000 we have the Let's say then I have a If I "monkey-patch"/replace the method only for the Now the thing is this - in the example below (stuff is named more uniquely than in above tables), I actually want to replace the entire class method What is weird here, is that even the function that is defined in the main file, So, I'm apparently not printing what I think are addresses of functions - and I think it's also confirmed by the fact that I have two printouts per each call, while I should have only one? How can I change the below code, so I print out the addresses that can help me confirm that the patching/overloading happened as expected? Here is the code,
Objects don't have methods; classes do. An object is simply a variable with a package associated with it. So the real layout is Changing the package affects all objects that use that package.
这篇关于打印Perl对象方法的地址? (用于重新定义Perl类方法)的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!$obj
实例进行"monkey-patch"/替换方法,则希望内存布局看起来像这样( $ perl cltest.pl
Starting Demo::Main...
Orig test_me!
1: DMFo: 8e63dc0 DMFo->test_me 8e916f8 DMF::test_me 8e916e8 repl_test_me 8e91748
Orig test_me!
-- CODE --
Subroutine Demo::My::Functions::test_me redefined at cltest.pl line 59.
Repl test_me!
Repl test_me!
2: DMFo: 8e63dc0 DMFo->test_me 8e916f8 DMF::test_me 8dfb708 repl_test_me 8dfb6c8
repl_test_me
中定义的函数也更改了地址-应该不应该!
cltest.pl
:use v5.10.1;
package Demo::My::Functions;
$INC{'Demo/My/Functions.pm'} = 1;
use warnings;
use strict;
use base 'Class::Accessor';
__PACKAGE__->mk_accessors(qw(test_me));
sub test_me {
my $self = shift;
print("Orig test_me!\n");
return 1;
}
sub test_also_me {
my $self = shift;
print("Orig test_also_me!\n");
return 1;
}
sub new {
my $class = shift;
my $self = {};
bless $self, $class;
return $self;
}
############################################################
package Demo::Main;
use warnings;
use strict;
print("Starting Demo::Main...\n");
my $DMFA = Demo::My::Functions->new();
sub repl_test_me {
my $self = shift;
print("Repl test_me!\n");
return 1;
}
# note: \&{$DMFA->test_me} calls!
printf("1: DMFo: %p DMFo->test_me %p DMF::test_me %p repl_test_me %p\n",
$DMFA, \&{$DMFA->test_me}, \&{'Demo::My::Functions::test_me'}, \&repl_test_me
);
print("-- " . ref(\&{$DMFA->test_me}) . " --\n");
{
no strict 'refs';
#~ *Demo::My::Functions::test_me = sub {my $self = shift; print("ReplIN test_me!\n"); return 1; }; # OK
#~ *Demo::My::Functions::test_me = *repl_test_me; # overloads
*Demo::My::Functions::test_me = \&repl_test_me; # overloads
};
# test it:
$DMFA->test_me();
# output addr again:
printf("2: DMFo: %p DMFo->test_me %p DMF::test_me %p repl_test_me %p\n",
$DMFA, \&{$DMFA->test_me}, \&{'Demo::My::Functions::test_me'}, \&repl_test_me
);
$ perl -MDevel::Peek -E'$o={}; Dump($o); bless($o); Dump($o); say \%main::'
SV = IV(0x26c2360) at 0x26c2370
REFCNT = 1
FLAGS = (ROK)
RV = 0x269a978
SV = PVHV(0x26a0400) at 0x269a978
REFCNT = 1
FLAGS = (SHAREKEYS)
ARRAY = 0x0
KEYS = 0
FILL = 0
MAX = 7
SV = IV(0x26c2360) at 0x26c2370
REFCNT = 1
FLAGS = (ROK)
RV = 0x269a978
SV = PVHV(0x26a0400) at 0x269a978
REFCNT = 1
FLAGS = (OBJECT,SHAREKEYS)
STASH = 0x269a7f8 "main"
ARRAY = 0x0
KEYS = 0
FILL = 0
MAX = 7
HASH(0x269a7f8) # Address of the main package.
+---------+
| |
| v
+-----------+ | +-----------+
| Reference | | | 0x269a7f8 |
| 0x26c2370 | | | Package |
+-----------+ | +-----------+
| | |
References | Contains
| | |
v | v
+-----------+ | +-----------+
| Hash | | | 0xXXXXXXX |
| 0x269a978 | | | Method |
+-----------+ | +-----------+
| |
Blessed into |
| |
+---------+
$ perl -E'
sub f { "a" }
my $o = bless({});
say join " ", \&f, $o->can("f"), $o->f;
*f = sub { "b" };
say join " ", \&f, $o->can("f"), $o->f;
'
CODE(0x311c680) CODE(0x311c680) a
CODE(0x3126f60) CODE(0x3126f60) b
$obj
which is an instance of some Class
which has Class::method
, then $obj
also has $obj->method
; I assume the simplified memory layout in that case would look something like this (tables made in LaTeX Table Generator; for the below one, src here):$obj->method
, which would simply (somehow) point to the actual Class::method
definition, which is (say) at 0x3500.sub
defined somewhere in the main file, somefunc
(ignore the prefixed $ in the tables), whose definition ends up at address 0x2000. $obj
instance, I'd expect the memory layout to look something like this (src here):Demo::My::Functions::test_me
with a method defined in the main file repl_test_me
. I don't really know what to expect of addresses, so I'm trying to show what I think are addresses before and after the method patching, using the %p
specifier of printf
. The code outputs this:$ perl cltest.pl
Starting Demo::Main...
Orig test_me!
1: DMFo: 8e63dc0 DMFo->test_me 8e916f8 DMF::test_me 8e916e8 repl_test_me 8e91748
Orig test_me!
-- CODE --
Subroutine Demo::My::Functions::test_me redefined at cltest.pl line 59.
Repl test_me!
Repl test_me!
2: DMFo: 8e63dc0 DMFo->test_me 8e916f8 DMF::test_me 8dfb708 repl_test_me 8dfb6c8
repl_test_me
, changes address - and it shouldn't?!cltest.pl
:use v5.10.1;
package Demo::My::Functions;
$INC{'Demo/My/Functions.pm'} = 1;
use warnings;
use strict;
use base 'Class::Accessor';
__PACKAGE__->mk_accessors(qw(test_me));
sub test_me {
my $self = shift;
print("Orig test_me!\n");
return 1;
}
sub test_also_me {
my $self = shift;
print("Orig test_also_me!\n");
return 1;
}
sub new {
my $class = shift;
my $self = {};
bless $self, $class;
return $self;
}
############################################################
package Demo::Main;
use warnings;
use strict;
print("Starting Demo::Main...\n");
my $DMFA = Demo::My::Functions->new();
sub repl_test_me {
my $self = shift;
print("Repl test_me!\n");
return 1;
}
# note: \&{$DMFA->test_me} calls!
printf("1: DMFo: %p DMFo->test_me %p DMF::test_me %p repl_test_me %p\n",
$DMFA, \&{$DMFA->test_me}, \&{'Demo::My::Functions::test_me'}, \&repl_test_me
);
print("-- " . ref(\&{$DMFA->test_me}) . " --\n");
{
no strict 'refs';
#~ *Demo::My::Functions::test_me = sub {my $self = shift; print("ReplIN test_me!\n"); return 1; }; # OK
#~ *Demo::My::Functions::test_me = *repl_test_me; # overloads
*Demo::My::Functions::test_me = \&repl_test_me; # overloads
};
# test it:
$DMFA->test_me();
# output addr again:
printf("2: DMFo: %p DMFo->test_me %p DMF::test_me %p repl_test_me %p\n",
$DMFA, \&{$DMFA->test_me}, \&{'Demo::My::Functions::test_me'}, \&repl_test_me
);
$ perl -MDevel::Peek -E'$o={}; Dump($o); bless($o); Dump($o); say \%main::'
SV = IV(0x26c2360) at 0x26c2370
REFCNT = 1
FLAGS = (ROK)
RV = 0x269a978
SV = PVHV(0x26a0400) at 0x269a978
REFCNT = 1
FLAGS = (SHAREKEYS)
ARRAY = 0x0
KEYS = 0
FILL = 0
MAX = 7
SV = IV(0x26c2360) at 0x26c2370
REFCNT = 1
FLAGS = (ROK)
RV = 0x269a978
SV = PVHV(0x26a0400) at 0x269a978
REFCNT = 1
FLAGS = (OBJECT,SHAREKEYS)
STASH = 0x269a7f8 "main"
ARRAY = 0x0
KEYS = 0
FILL = 0
MAX = 7
HASH(0x269a7f8) # Address of the main package.
+---------+
| |
| v
+-----------+ | +-----------+
| Reference | | | 0x269a7f8 |
| 0x26c2370 | | | Package |
+-----------+ | +-----------+
| | |
References | Contains
| | |
v | v
+-----------+ | +-----------+
| Hash | | | 0xXXXXXXX |
| 0x269a978 | | | Method |
+-----------+ | +-----------+
| |
Blessed into |
| |
+---------+
$ perl -E'
sub f { "a" }
my $o = bless({});
say join " ", \&f, $o->can("f"), $o->f;
*f = sub { "b" };
say join " ", \&f, $o->can("f"), $o->f;
'
CODE(0x311c680) CODE(0x311c680) a
CODE(0x3126f60) CODE(0x3126f60) b