सी # में विस्तार enums

काश .NET में एनम अधिक शक्तिशाली होते। और मैं प्यार करता हूँ। नेट! आप एक ही चीज़ को पूरा करने के लिए विशेषताओं का उपयोग कर सकते हैं। नीचे दिए गए कोड को एक बार लिखें और हर जगह इसका इस्तेमाल करें। यह एक लंबा जवाब होगा लेकिन मुझे लगता है कि यह एक बहुत अच्छा समाधान है इसलिए धैर्य रखें!

प्रयोग

SomeEnum e = SomeEnum.ValueTwo;
string description = e.GetDescription();

Enum

Enum और उसके मूल्यों का वर्णन करने के लिए विशेषताओं का उपयोग करें।

[DescriptiveEnumEnforcement(DescriptiveEnumEnforcement.EnforcementTypeEnum.ThrowException)]
public enum SomeEnum
{
    [Description("Value One")]
    ValueOne,

    [Description("Value Two")]
    ValueTwo,

    [Description("Value 3")]
    ValueThree
}

विवरणविशेषता

/// <summary>Indicates that an enum value has a description.</summary>
[AttributeUsage(AttributeTargets.Field)]
public class DescriptionAttribute : System.Attribute
{
    /// <summary>The description for the enum value.</summary>
    public string Description { get; set; }

    /// <summary>Constructs a new DescriptionAttribute.</summary>
    public DescriptionAttribute() { }

    /// <summary>Constructs a new DescriptionAttribute.</summary>
    /// <param name="description">The initial value of the Description property.</param>
    public DescriptionAttribute(string description)
    {
        this.Description = description;
    }

    /// <summary>Returns the Description property.</summary>
    /// <returns>The Description property.</returns>
    public override string ToString()
    {
        return this.Description;
    }
}

वर्णनात्मकEnumEnforcementAttribute

यह सुनिश्चित करने के लिए एक विशेषता कि आपके एनम को ठीक से कॉन्फ़िगर किया गया है।

/// <summary>Indicates whether or not an enum must have a NameAttribute and a DescriptionAttribute.</summary>
[AttributeUsage(AttributeTargets.Enum)]
public class DescriptiveEnumEnforcementAttribute : System.Attribute
{
    /// <summary>Defines the different types of enforcement for DescriptiveEnums.</summary>
    public enum EnforcementTypeEnum
    {
        /// <summary>Indicates that the enum must have a NameAttribute and a DescriptionAttribute.</summary>
        ThrowException,

        /// <summary>Indicates that the enum does not have a NameAttribute and a DescriptionAttribute, the value will be used instead.</summary>
        DefaultToValue
    }

    /// <summary>The enforcement type for this DescriptiveEnumEnforcementAttribute.</summary>
    public EnforcementTypeEnum EnforcementType { get; set; }

    /// <summary>Constructs a new DescriptiveEnumEnforcementAttribute.</summary>
    public DescriptiveEnumEnforcementAttribute()
    {
        this.EnforcementType = EnforcementTypeEnum.DefaultToValue;
    }

    /// <summary>Constructs a new DescriptiveEnumEnforcementAttribute.</summary>
    /// <param name="enforcementType">The initial value of the EnforcementType property.</param>
    public DescriptiveEnumEnforcementAttribute(EnforcementTypeEnum enforcementType)
    {
        this.EnforcementType = enforcementType;
    }
}

विवरण प्राप्त करना

/// <summary>Provides functionality to enhance enumerations.</summary>
public static partial class EnumUtil
{
    /// <summary>Returns the description of the specified enum.</summary>
    /// <param name="value">The value of the enum for which to return the description.</param>
    /// <returns>A description of the enum, or the enum name if no description exists.</returns>
    public static string GetDescription(this Enum value)
    {
        return GetEnumDescription(value);
    }

    /// <summary>Returns the description of the specified enum.</summary>
    /// <param name="value">The value of the enum for which to return the description.</param>
    /// <returns>A description of the enum, or the enum name if no description exists.</returns>
    public static string GetDescription<T>(object value)
    {
        return GetEnumDescription(value);
    }

    /// <summary>Returns the description of the specified enum.</summary>
    /// <param name="value">The value of the enum for which to return the description.</param>
    /// <returns>A description of the enum, or the enum name if no description exists.</returns>
    public static string GetEnumDescription(object value)
    {
        if (value == null)
        return null;

        Type type = value.GetType();

        //Make sure the object is an enum.
        if (!type.IsEnum)
            throw new ApplicationException("Value parameter must be an enum.");

        FieldInfo fieldInfo = type.GetField(value.ToString());
        object[] descriptionAttributes = fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), false);

        //If no DescriptionAttribute exists for this enum value, check the DescriptiveEnumEnforcementAttribute and decide how to proceed.
        if (descriptionAttributes == null || descriptionAttributes.Length == 0)
        {
            object[] enforcementAttributes = fieldInfo.GetCustomAttributes(typeof(DescriptiveEnumEnforcementAttribute), false);

            //If a DescriptiveEnumEnforcementAttribute exists, either throw an exception or return the name of the enum instead.
            if (enforcementAttributes != null && enforcementAttributes.Length == 1)
            {
                DescriptiveEnumEnforcementAttribute enforcementAttribute = (DescriptiveEnumEnforcementAttribute)enforcementAttributes[0];

                if (enforcementAttribute.EnforcementType == DescriptiveEnumEnforcementAttribute.EnforcementTypeEnum.ThrowException)
                    throw new ApplicationException("No Description attributes exist in enforced enum of type '" + type.Name + "', value '" + value.ToString() + "'.");

                return GetEnumName(value);
            }
            else //Just return the name of the enum.
                return GetEnumName(value);
        }
        else if (descriptionAttributes.Length > 1)
            throw new ApplicationException("Too many Description attributes exist in enum of type '" + type.Name + "', value '" + value.ToString() + "'.");

        //Return the value of the DescriptionAttribute.
        return descriptionAttributes[0].ToString();
    }
}