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Discussion on: Can you pass local functions to a method? If so, what type is a function?

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Replies for: But what if I want to accept ANY kind of function? With a custom amount of args, and a custom return value?

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Kasey Speakman • • Edited

Custom return value is easy. You just have to add a generic parameter(s) to the function.

public U Transform<T, U>(Func<T, U> transformFn, T value)
{
    return transformFn(value);
}
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To accept a varied amount of arguments, you will have to add method overloads with different numbers of generic type parameters. Only signatures are shown below.

V Transform<T, U, V>(Func<T, U, V> transformFn, T t, U u);
W Transform<T, U, V, W>(Func<T, U, V, W> transformFn, T t, U u, V v);
X Transform<T, U, V, W, X>(Func<T, U, V, W, X> transformFn, T t, U u, V v, W w);
// etc.
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Note that some of the types T, U, V, etc could actually be the same type. Different letters are used in case they are different.

The above code does not make sense to use in practice, but it demonstrates the concept.