CODEWITHSUNDEEP
c#.netdictionary
Scottingham
Scottingham

Reputation: 946

default value for object in dictionary

I have a dictionary set up like so: Dictionary <string, ItemProperties>

the ItemProperties object looks like this (the base class is abstract):

public class StringProperty : ItemProperty
{
    public string RawProp { get; set; }
    public string RenderedProp { get; set; }
}

Is there a way to get the RenderedProp value like so (assuming the dictionary variable is called Properties):

string value = Properties[keyname];

versus

string value = Properties[keyname].RenderedProp;

Upvotes: 1

Views: 1435

Answers (4)

Robert Harvey
Robert Harvey

Reputation: 180787

You can create your own PropertyDictionary with a custom Indexer method.

public class PropertyDictionary
{
    Dictionary <string, StringProperty> dictionary;

    public PropertyDictionary()
    {
        dictionary = new Dictionary <string, StringProperty>();
    }

    // Indexer; returns RenderedProp instead of Value
    public string this[string key]
    {
        get { return dictionary[key].RenderedProp; }
        set { dictionary[key].RenderedProp = value; }
    }
}

Upvotes: 5

DasKr&#252;melmonster
DasKr&#252;melmonster

Reputation: 6060

You could implement an extension method for your Dictionary<>:

public static int GetRP(this Dictionary <string, ItemProperties> dict, string key)
{
    return dict[key].RenderedProp;
}

You'd have to call it directly though, without having the indexer notation. Overall code is similarly short if you use a short name.

Upvotes: 1

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726479

There is a solution, but I would strongly recommend against it: define an implicit conversion operator from StringProperty to string, and return RenderedProp to the caller:

public class StringProperty : ItemProperty
{
    public string RawProp { get; set; }
    public string RenderedProp { get; set; }
    public static implicit operator string(StringProperty p)
    {
        return p.RenderedProp;
    }
}

The Dictionary needs to use StringProperty, not ItemProperty as the value type in order for the operator to apply. The same is true about your Properties[keyname].RenderedProp code as well.

Upvotes: 2

Jon Skeet
Jon Skeet

Reputation: 1499780

No. If you want to store the RenderedProp value in the dictionary, just make it a Dictionary<string, string> and add it appropriately. If you do actually need the full ItemProperties in the dictionary, but frequently want to get at the RenderedProp, you could always create a method to do that (wherever the dictionary lives).

Note that if RenderedProp is only specified in StringProperty (not in other subclasses of ItemProperties) then you need to consider what would happen for non-StringProperty values in the dictionary.

Upvotes: 3

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