许多程序员会混淆元类和基类的不同。
Many programmers are confused about the difference between a metaclass and a base class.
它包含许多代理和元类。
为C手工创建必需的元类，可以避免元型冲突
The metatype conflict can be avoided by manually creating the needed metaclass for C
类的属性(包括元类和原型的关联)应该选择这个属性。
Properties of class type (including metaclass and stereotype associations) should have this option selected.
元类扩展的EClass的具体子类型将会自动被添加。
Concrete subtypes of the metaclass extension's EClass will automatically be added.
从注释到包，包括类本身，UML中的每个概念都有一个元类。
From comments to packages, including classes themselves, every concept in UML has a metaclass.
元类将创建此类(作为一个新式类)并将其传递给类初始化器过程。
The metaclass will create the class (as a new style one) and will pass it to the class initializer procedure.
应该用一个附加到XO、行为是动态决定的自定义元类来完成上述工作。
You could accomplish the above sort of job with a custom metaclass, attached to XO, but with behavior determined dynamically.
如果不属于这种情形，那就跳过元类，使您(和您的用户)的生活更加惬意。
If this is not your case, skip the metaclass and make your life (and that of your users) happier.
如果在这个配置文件中没有定义图标，这个对应元类扩展的图标就会被使用。
If there is no icon defined in the profile, the icon corresponding to the metaclass extension will be used.
当解析发生时，在查找实例化元类之前，会先遵循它的MRO对类进行查找。
As it turns out, lookup on a class follows its MRO before it looks in its instantiating metaclass.
跟流行的观点相反，这是一个在大多数时候都不需要而且不想要自定义元类的工作。
Contrary to popular belief, this is a job where most of the time you do not need and you do not want a custom metaclass.
最后，您将为整个产品线开发一个功能模型(以uml元类关系图表示)，如图3所示。
Finally, you develop a feature model (expressed in UML metaclass diagrams) for the entire product line, as shown in Figure 3.
分析阶段的产物是一个元类模型，此模型描述候选服务、候选服务的角色构造型及其操作。
The outcome of the analysis phase is a metaclass model that describes candidate services, their role stereotypes, and their operations.
注意到如果这个元类扩展以前是一个抽象的EClass，它将不会显示在这个列表中。
Observe that if the metaclass extension was to an abstract EClass, it will not show in the list.
用户应该理解元类型冲突的原因和解决方案，当您想使用多个定制的元类时，这将非常必要。
Users should understand the cause and the resolution of metatype conflicts. This becomes essential when you want to use more than one custom metaclass.
换句话说，只有当想在派生类上运行代码，又不想让用户注意到时，才应该使用自定义元类。
In other words, you should use a custom metaclass only when your real intention is to have code running on derived classes without users of those classes noticing it.
例如，假设存在一个原型s，它扩展了元类Actor并且有一个命名叫attr1的属性。
For example, suppose that there is a stereotype s, which extends the metaclass Actor and has an attribute named attr1.
表一列出了UML 2.0元模型中在UMLprofile中用作原型元类的元素。
Table 1 lists the elements of the UML 2.0 meta model that are used as meta classes for stereotypes in the UML Profile.
Duke是一个类，也是元类Nobility的一个实例——属性的查找过程与其他对象一致。
As well as being a class, Duke is an instance of the metaclass Nobility — attribute lookup proceeds as with any object.
某些实例对象就是类本身，并且所有的类都是相应元类的实例，甚至类也只能通过实例化机制生成。
Some instance objects are themselves classes; and all classes are instances of a corresponding metaclass. Even classes only come into existence through the instantiation mechanism.
对于本文，我们坚持严肃的立场：我们把在不用元类也能解决问题的情况下使用元类都视为元类滥用。
For this article, we take a ruthless stance: we consider metaclass abuse any usage of a metaclass where you could have solved the same problem equally well without a custom metaclass.
您觉得对于类初始化这类简单的工作使用自定义元类是杀鸡用牛刀，所以想要使用一种更为简单的解决方案。
You feel that a custom metaclasses is overkill for the simple job of class initialization, and you would rather use a simpler solution.
在下面的例子中，字符串msg的实例有一个元类，我们可以通过metaClass属性访问该元类。
In the following example, the MSG String instance has got a meta-class that we can access through the metaClass property.
元类属性的可用性是不会传递的，也就是说，元类的属性是对它的实例是可用的，但是对它的实例的实例是不可用的。
The availability of metaclass attributes is not transitive; in other words, the attributes of a metaclass are available to its instances, but not to the instances of the instances.
正如上一节中介绍的一样，decorator并不能完全取代元类挂钩，因为它们只修改了方法，而未添加或删除方法。
As mentioned in the last section, decorators could not completely replace the metaclass hook since they only modify methods rather than add or delete methods.
UML 2.1规范所定义的元类，可以被用来指定原型属性集的类型，通过在原型和所需的元类之间创建一个元类的关联。
A UML 2.1 defined metaclass can be used to specify the type of stereotype attributes by creating a metaclass association between the stereotype and the desired metaclass.
将其他Product添加到Catalog完全是一个数据驱动过程，而且不会对类模型产生影响，因此将Product建模为一个元类会使我们的模型更加灵活。
Modeling Product as a meta-class makes our model more flexible in that adding additional Products to the Catalog is purely a data-driven process and doesn't impact the class model.
Category类包含类别名以及以 ArrayList.BookItem 类形式表示的书籍的元数据，这些元数据包括书名、作者、价格和类别。
The Category class includes the category name and the book's metadata in the form of the ArrayList.BookItem class, which contains the book's name, author, price, and category.
例如，如果元编程系统自动生成类中的一个方法，但是后来又必须对这个方法进行修改，那么应该如何实现这种功能呢？
For example, if the metaprogramming system auto-generates a method within a class, but later that method must be tweaked, how do you implement something like that?
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