如何实现属性的一系列常量预定义“状态”？

Question

I have a property LegalCaseStatus . My intention is to make the property to accept a predefined range of approved values. The range must be visible and unchanged throughtout my program. Here's an example of the list:

Plaintiff
Defendant
Third Party
Debitor
Creditor
Petitioner

So, the best way I could think of is to declare a static class, and fill it with corresponding constants:

public static class Participants
{
    public const byte 
        Piaintiff = 0, 
        Defendant = 1, 
        ThirdParty = 2, 
        Debitor= 3, 
        Creditor = 4, 
        Petitioner = 5;
}

so after using a namespace I could just do:

public byte LegalCaseStasus = Plaintiff;

the only problem is, since it's just a byte member it'll accept anything that is byte :

LegalCaseStatus = 99; // ok
LegalCaseStatus = SomeOtherByteConstant; // ok

How do I protect the member LegalCaseStatus ? Is my solution generally correct?

Answer 1

You can use enums - An enum is a special "class" that represents a group of constants (unchangeable/read-only variables). Sounds like the thing you describe in your question:

public enum Participants
{
        Piaintiff = 0,
        Defendant = 1,
        ThirdParty = 2,
        Debitor = 3,
        Creditor = 4,
        Petitioner = 5
}

After the enum definition you can use it exactly the way you want to:

Participants LegalCaseStasus = Participants.ThirdParty;
LegalCaseStasus = 99;   // ERROR      
byte underlying_value = (byte)LegalCaseStasus; // value == 2

Note: The underlying value of an enum is int ! When you cast to byte you need to make sure there are no predefined values that exceed the byte limit.