Ada中的派生类型和子类型 [英] Derived types and sub types in Ada

问题描述

有什么区别？

推荐答案

首先，术语：是 Ada，而不是 ADA-以 Ada Lovelace的名字命名；

First of all, terminology: it's "Ada", not "ADA" -- it's named after "Ada Lovelace"; it is not an acronym.

子类型与其基本类型兼容，因此可以将基本类型的操作数与基本类型的操作数混合。例如：

A subtype is compatible with its base type, so you can mix operands of the base type with operands of the base type. For example:

subtype Week_Days is Integer range 1..7;

由于这是子类型，因此您可以（例如）添加 1 到一个工作日即可获得下一个工作日。

Since this is a subtype, you can (for example) add 1 to a weekday to get the next weekday.

派生类型是一种完全独立的类型，其特征与基本类型相同。您不能将派生类型的操作数与基本类型的操作数混合。例如，如果您使用：

A derived type is a completely separate type that has the same characteristics as its base type. You cannot mix operands of a derived type with operands of the base type. If, for example, you used:

type Week_Day is new Integer range 1..7;

然后，您不可以在工作日中添加整数得到另一个工作日。要对派生类型进行操作，通常需要自己定义这些操作（例如，创建程序包）。同时，派生类型会继承其基本类型的所有操作（即使有些操作可能没有意义），因此您仍然会获得加法。

Then you would not be able to add an integer to a weekday to get another weekday. To do manipulations on a derived type, you'd normally define those manipulations yourself (e.g., create a package). At the same time, a derived type does "inherit" all the operations of its base type (even some that may not make sense) so you do still get addition.

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