如何在 Perl 中用子函数覆盖父类函数？

发布于 2024-08-22 07:32:41 字数 378 浏览 5 评论 0原文

我想替换子类中的父函数（Somefunc），所以当我调用 Main 过程时它应该失败。

在 Perl 中可以吗？

代码：

package Test;

use strict;
use warnings;

sub Main()
{
    SomeFunc() or die "Somefunc returned 0";
}

sub SomeFunc()
{
    return 1;
}

package Test2;

use strict;
use warnings;

our @ISA = ("Test");

sub SomeFunc()
{
    return 0;
}

package main;

Test2->Main();

原文

I would like to replace parent function (Somefunc) in child class, so when I call Main procedure it should fail.

Is it possible in Perl?

Code:

package Test;

use strict;
use warnings;

sub Main()
{
    SomeFunc() or die "Somefunc returned 0";
}

sub SomeFunc()
{
    return 1;
}

package Test2;

use strict;
use warnings;

our @ISA = ("Test");

sub SomeFunc()
{
    return 0;
}

package main;

Test2->Main();

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情独悲 2024-08-29 07:32:41

当您调用 Test2->Main() 时，包名称将作为第一个参数传递给被调用函数。您可以使用参数来寻址正确的函数。

sub Main
{
    my ($class) = @_;
    $class->SomeFunc() or die "Somefunc returned 0";
}

在此示例中，$class 将是 "Test2"，因此您将调用 Test2->SomeFunc()。更好的解决方案是使用实例（即 bless Test::new 中的对象，使用 $self 而不是 $类）。更好的是使用 Moose，它解决了 Perl 中面向对象编程的很多问题。

When you call Test2->Main(), the package name is passed as the first parameter to the called function. You can use the parameter to address the right function.

sub Main
{
    my ($class) = @_;
    $class->SomeFunc() or die "Somefunc returned 0";
}

In this example, $class will be "Test2", so you will call Test2->SomeFunc(). Even better solution would be to use instances (i.e., bless the object in Test::new, use $self instead of $class). And even better would be to use Moose, which solves a lot of problems with object-oriented programming in Perl.

回复收藏 0 原文

怼怹恏 2024-08-29 07:32:41

为了使继承起作用，您需要使用 -> 运算符在类或对象上将函数作为方法调用。您似乎已经为 Test2->Main() 的调用弄清楚了这一点，但是您想要以 OO 方式运行的所有方法都必须以这种方式调用。

package Test;

use strict;
use warnings;

sub Main
{
    my $class = shift;
    $class->SomeFunc() or die "Somefunc returned 0";
}

sub SomeFunc
{
    return 1;
}

package Test2;

our @ISA = ("Test");

sub SomeFunc
{
    return 0;
}

package main;

Test2->Main();

请参阅 perlboot 以获得简单的介绍和 perltoot 了解更多详细信息。

另外，当你声明子例程名称时，不要在它们后面加上括号——它不会按照你的想法做。

In order for inheritance to work you need to call your functions as methods, either on a class or an object, by using the -> operator. You seem to have figured this out for your call to Test2->Main(), but all methods that you want to behave in an OO way must be called this way.

package Test;

use strict;
use warnings;

sub Main
{
    my $class = shift;
    $class->SomeFunc() or die "Somefunc returned 0";
}

sub SomeFunc
{
    return 1;
}

package Test2;

our @ISA = ("Test");

sub SomeFunc
{
    return 0;
}

package main;

Test2->Main();

See perlboot for a gentle introduction and perltoot for more details.

Also, don't put parens after your subroutine names when you declare them -- it doesn't do what you think.

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