将SUPER引用到超类的对象

Question

请参阅oper http://perldoc.perl.org/perlobj.html上的perldoc

根据文档:"重要的是要注意SUPER指的是当前包的超类,而不是指对象的超类."

现在,我处于这样一种情况,我需要SUPER来引用对象的超类.

所以,寻找任何方法来实现它.

Answer 1

你真的需要做这样的事情是相当罕见的,通常这是一个迹象表明你在某个物体内部的捣乱会以后会再次咬你.如果真的需要做什么,你可以改变你的包只是为了方法调用来改变SUPER看到的东西,或者通过调用完整的方法名来覆盖方法查找.

{
    package BaseClass;
    sub new { bless \my $self, shift; }
    sub foo { 
        my $self = shift; 
        print "BaseClass::foo()\n";
    }
}
{
    package SubClass;
    our @ISA = qw(BaseClass);
    sub foo { 
        my $self = shift; 
        print "SubClass::foo()\n"; 
        $self->SUPER::foo(); 
    }
}
{
    package ParentClass;
    sub new { bless \my $self, shift; }
    sub bar { 
        my $self = shift; 
        print "ParentClass::bar()\n"; 
    }
}
{
    package ChildClass;
    our @ISA = qw(ParentClass);
    sub foo {
        my $other = SubClass->new();
        print "ChildClass::foo()\n";
        # fails trying to find ParentClass::foo()
        eval { $other->SUPER::foo(); } or warn $@;
        # thinks this is SubClass and finds BaseClass::foo()
        { package SubClass; $other->SUPER::foo(); }
        # if you know the correct class that SUPER::foo() would have called (but this will also work if it was the wrong class)
        $other->BaseClass::foo();
    }
    sub bar { 
        my $self = shift; 
        print "ChildClass::bar()\n"; 
        $self->SUPER::bar(); 
    }
}

my $obj_1 = SubClass->new();
$obj_1->foo();

my $obj_2 = ChildClass->new();
$obj_2->bar();
$obj_2->foo();

更简洁的选择是重构您的方法,以便您可以访问基类和子类方法,而无需尝试破坏对象系统.

{
    package BaseClass;
    sub new { bless \my $self, shift; }
    sub foo { 
        my $self = shift; 
        print "BaseClass::foo()\n"; 
    }
}
{
    package SubClass;
    our @ISA = qw(BaseClass);
    sub bar { 
        my $self = shift; 
        print "SubClass::bar()\n"; 
        $self->SUPER::foo(); 
    }
}

my $obj = SubClass->new();
$obj->foo();
$obj->bar();

或者提供一种调用基类方法的方法.

{
    package BaseClass;
    sub new { bless \my $self, shift; }
    sub foo { 
        my $self = shift; 
        print "BaseClass::foo()\n"; 
    }
}
{
    package SubClass;
    our @ISA = qw(BaseClass);
    sub foo { 
        my $self = shift; 
        print "SubClass::foo()\n"; 
        $self->SUPER::foo(); 
    }
    sub bar { 
        my $self = shift; 
        $self->SUPER::foo(); 
    }
}

my $obj = SubClass->new();
$obj->foo();
$obj->bar();

最好的答案实际上取决于你真正想要做的是为什么要求你解决标准继承问题.