Custom Attributes, named parameters and reflection

[Techno]

Hi.
I am trying to find the most fasted way of doing this when it comes to reflection.

Say I have a custom attribute which allows multiples on a property.

I then want to get a list of properties which contains this custom attribute. Thats ok, I get a collection of these attributes for that property.
I then, for each of the attributes found, want to get the value for a specific named argument.

how can I do this and in the most efficient way? Reflection does have a hit but im sure with some decent algorithms/different calls it can save those few ms's

thanks

[jmcilhinney]

I'm not sure that there is any way other than something like this:

private Dictionary<string, string[]> GetAttributeValues(object source)
{
    var attributeValuesByPropertyName = new Dictionary<string, string[]>();
    var properties = source.GetType().GetProperties();

    foreach (var property in properties)
    {
        var attributes = property.GetCustomAttributes(typeof(MultipleValueAttribute), false);
        var attributesLength = attributes.Length;

        if (attributesLength > 0)
        {
            var values = new string[attributesLength];

            for (int i = 0; i < attributesLength; i++)
            {
                values[i] = ((MultipleValueAttribute)attributes[i]).Value;
            }

            attributeValuesByPropertyName.Add(property.Name, values);
        }
    }

    return attributeValuesByPropertyName;
}

You could shorten that code with a bit of LINQ but that would make it slower to execute, if only by a little. Sample usage:

var obj = new Test();
var attributeValues = this.GetAttributeValues(obj);

foreach (var propertyName in attributeValues.Keys)
{
    MessageBox.Show(string.Join("\r\n", attributeValues[propertyName]), propertyName);
}

That was based on the following attribute:

[AttributeUsage(AttributeTargets.Property, AllowMultiple = true)]
public class MultipleValueAttribute : Attribute
{
    public string Value { get; set; }
}

[Techno]

thanks. I just managed to figure it out before you posted thats pretty much what I have.

[jmcilhinney]

I'm sure that it's not quite as glamorous as mine.