How can I discover the keys used in a C# indexer?

We have a legacy class that uses an indexer to allow people to add arbitrary key-value pairs:

legacyInstance["myKey"] = value;

Sadly, we can't look at or modify the code for this class. We can only 开发者_如何转开发access it through its various properties.

What we need to do is clone this object in an intelligent way. Normal properties are simple to clone, of course:

myClone.blargle = legacyInstance.blargle;

But how do we discover all of the keys that someone may have added to a particular object instance in order to clone them correctly? Ideally something like this:

string[] keys = legacyInstance.<#magic!#>;
foreach (string key in keys)
{
    myClone[key] = legacyInstance[key];
}

And while I suspect the magic may involve some Reflection, getting at it is proving difficult since I am a Reflection tyro.

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Grab the ILSpy and get into sources. If your collection doesn't expose members to iterate over keys (like Dictionary exposes Keys) then this is your only option. By the way, may be you collection is IEnumerable? Actually it is strange for a collection not to provide any iteration facilities. Is not it called YouCanOnlyUseIndexCollection?