Question

我有一个关于Perl MooseX::Declare的问题。我想在一个.pm文件中放置多个类。我如何制作这个文件，文件名是什么，因为.pm文件有多个类？

例如

use MooseX::Declare;
class Point {

   has 'x' => ( isa => 'Num', is => 'rw' );
   has 'y' => ( isa => 'Num', is => 'rw' );

   method clear {
      $self->x(0);
      $self->y(0);
   }
   method set_to( Num $x, Num $y) {
      $self->x($x);
      $self->y($y);
   }
}


class Point3D {

   has 'z' => ( isa => 'Num', is => 'rw' );

   method clear {
      $self->z(0);
   }
   method set_to( Num $x, Num $y, Num $z) {
      $self->x($x);
      $self->y($y);
      $self->z($z);
   }
}

如何保存此pm文件 - 按头等名称或第二类名称？

Answer 1

由于每个单一文件的指南仅用于帮助您组织自己的代码，因此您可以将文件命名为您想要的任何内容。

那就是说，指南存在的充分理由。

在perlmonks您可能想要查看有关此主题的有趣讨论。

我建议不要对每个文件使用多个类，除非你将它们放在一个公共命名空间中。

{
    package Geometrics;

    class Point {
        ...
    }

    class Point3D {
        ...
    }
}

如果你走那条路，你可以相应地命名你的.pm文件（即Geometrics.pm）。

如果不这样做，假设你的课程与主题相关（就像它们似乎那样），那么Points.pm之类的东西也许是恰当的。

修改：

至于如何“从外部调用或使用类（Point，Point3D）”或如何实例化模块中定义的类：

# import the package use Geometrics qw(Point Point3d); # or # use Geometrics ('Point' 'Point3d'); # instantiate a Point my $point = Point->new(); # instantiate a Point3D my $point3d = Point3D->new();

您也可以通过以下任一方式导入包：

# import the package but do not import any symbols from it use Geometrics ();

或

# While you can import the package this way, please do not do so. # import the package with ALL symbols use Geometrics;

但这样做会有一些警告......

# importing the package with no symbols use Geometrics (); # means instantiation of objects must be fully-qualified my $point = Geometrics::Point->new(); my $point3d = Geometrics::Point3D->new();

# importing the package with ALL symbols use Geometrics; # makes instantiation of objects simpler my $point = Point->new(); my $point3d = Point3D->new(); # BUT because all symbols are imported with the package, # overwriting of symbols can occur too easily. # If I were to import the package Foo this way (which has the symbol Bar defined) use Foo; # and then import the package Baz this way (which also has the symbol Bar defined) use Baz; # I no longer have access to Foo:Bar as that has been over-written by Baz::Bar # because I imported the packages with ALL symbols by default. # The lesson here is to code defensively and: # only import those symbols you intend to use, or # don't import any symbols and fully-qualify everything.

Answer 2

作为一般规则，不要在一个文件中放置多个类。

我以前经常看到的异常是相关类，尤其是顶级类的辅助类或子类。在这些情况下，它们总是被分组到一个包中，文件名是包名。

在Perl中，如何将多个类放在单个.pm文件中

2 个答案: