在最终不需要计算器的情况下将枚举定义为 2 的标志/幂的任何技巧? [英] Any trick to defining an enum as flags/powers of 2 without eventually needing a calculator?

问题描述

我知道我可以乘法但我不想做懒惰的编程.

I know I can multiply but being the lazy programming I am I do not want to.

有没有人设计了一些魔法来将枚举自动编号为 2 的幂?

Has anyone devised some sorcery to auto number the enums as powers of two?

下面是我为了让它具体化的例子:

Here's the example I have just to make it concrete:

[Flags]
private enum Targets : uint
{
    None = 0,
    Campaigns = 1,
    CampaignGroups = 2,
    Advertisers = 4,
    AdvertiserGroups = 8,
    AffiliateGroups = 16,
    Affiliates = 32,
    Creatives = 64,
    DetailedLeads = 128,
    DetailedSales = 256,
    ProgramLeads = 512,
    CreativeDeployments = 1024,
    CampaignCategories = 2048,
    Payouts = 4096,
    All = uint.MaxValue
}

推荐答案

将值写为移位的位并让编译器进行数学运算:

Write the values as shifted bits and let the compiler do the math:

[Flags]
private enum Targets : uint
{
    None                = 0,
    Campaigns           = 1,
    CampaignGroups      = 2 << 0,
    Advertisers         = 2 << 1,
    AdvertiserGroups    = 2 << 2,
    AffiliateGroups     = 2 << 3,
    Affiliates          = 2 << 4,
    Creatives           = 2 << 5,
    DetailedLeads       = 2 << 6,
    DetailedSales       = 2 << 7,
    ProgramLeads        = 2 << 8,
    CreativeDeployments = 2 << 9,
    CampaignCategories  = 2 << 10,
    Payouts             = 2 << 11,
    // etc.
}

James 的建议也不错.事实上，我更喜欢这种方式.你也可以这样写:

James's suggestion is a good one, too. In fact I like this way even better. You could also write it like this:

[Flags]
private enum Targets : uint
{
    None                = 0,
    Campaigns           = 1 << 0,
    CampaignGroups      = 1 << 1,
    Advertisers         = 1 << 2,
    AdvertiserGroups    = 1 << 3,
    AffiliateGroups     = 1 << 4,
    // etc.
}

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