DefaultValueAttribute.cs

Go to the documentation of this file.

using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Reflection;
using System.Threading;
 
namespace System.ComponentModel;
 
[AttributeUsage(AttributeTargets.All)]
public class DefaultValueAttribute : Attribute
{
    private object _value;
 
    private static object s_convertFromInvariantString;
 
    public virtual object? Value => _value;
 
    [RequiresUnreferencedCode("Generic TypeConverters may require the generic types to be annotated. For example, NullableConverter requires the underlying type to be DynamicallyAccessedMembers All.")]
    public DefaultValueAttribute([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] Type type, string? value)
    {
        if (type == null)
        {
            return;
        }
        try
        {
            if (TryConvertFromInvariantString(type, value, out var conversionResult2))
            {
                _value = conversionResult2;
            }
            else if (type.IsSubclassOf(typeof(Enum)) && value != null)
            {
                _value = Enum.Parse(type, value, ignoreCase: true);
            }
            else if (type == typeof(TimeSpan) && value != null)
            {
                _value = TimeSpan.Parse(value);
            }
            else
            {
                _value = Convert.ChangeType(value, type, CultureInfo.InvariantCulture);
            }
            [RequiresUnreferencedCode("Generic TypeConverters may require the generic types to be annotated. For example, NullableConverter requires the underlying type to be DynamicallyAccessedMembers All.")]
            static bool TryConvertFromInvariantString([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] Type typeToConvert, string stringValue, out object conversionResult)
            {
                conversionResult = null;
                if (s_convertFromInvariantString == null)
                {
                    MethodInfo methodInfo = Type.GetType("System.ComponentModel.TypeDescriptor, System.ComponentModel.TypeConverter", throwOnError: false)?.GetMethod("ConvertFromInvariantString", BindingFlags.Static | BindingFlags.NonPublic);
                    Volatile.Write(ref s_convertFromInvariantString, (methodInfo == null) ? new object() : methodInfo.CreateDelegate(typeof(Func<Type, string, object>)));
                }
                if (!(s_convertFromInvariantString is Func<Type, string, object> func))
                {
                    return false;
                }
                try
                {
                    conversionResult = func(typeToConvert, stringValue);
                }
                catch
                {
                    return false;
                }
                return true;
            }
        }
        catch
        {
        }
    }
 
    public DefaultValueAttribute(char value)
    {
        _value = value;
    }
 
    public DefaultValueAttribute(byte value)
    {
        _value = value;
    }
 
    public DefaultValueAttribute(short value)
    {
        _value = value;
    }
 
    public DefaultValueAttribute(int value)
    {
        _value = value;
    }
 
    public DefaultValueAttribute(long value)
    {
        _value = value;
    }
 
    public DefaultValueAttribute(float value)
    {
        _value = value;
    }
 
    public DefaultValueAttribute(double value)
    {
        _value = value;
    }
 
    public DefaultValueAttribute(bool value)
    {
        _value = value;
    }
 
    public DefaultValueAttribute(string? value)
    {
        _value = value;
    }
 
    public DefaultValueAttribute(object? value)
    {
        _value = value;
    }
 
    [CLSCompliant(false)]
    public DefaultValueAttribute(sbyte value)
    {
        _value = value;
    }
 
    [CLSCompliant(false)]
    public DefaultValueAttribute(ushort value)
    {
        _value = value;
    }
 
    [CLSCompliant(false)]
    public DefaultValueAttribute(uint value)
    {
        _value = value;
    }
 
    [CLSCompliant(false)]
    public DefaultValueAttribute(ulong value)
    {
        _value = value;
    }
 
    public override bool Equals([NotNullWhen(true)] object? obj)
    {
        if (obj == this)
        {
            return true;
        }
        if (!(obj is DefaultValueAttribute defaultValueAttribute))
        {
            return false;
        }
        if (Value == null)
        {
            return defaultValueAttribute.Value == null;
        }
        return Value.Equals(defaultValueAttribute.Value);
    }
 
    public override int GetHashCode()
    {
        return base.GetHashCode();
    }
 
    protected void SetValue(object? value)
    {
        _value = value;
    }
}