Question

Why would this compile:

public Dictionary<ValueLineType,                    Func<HtmlHelper,                         string,                         object,                         Type,                         string>> constructor =         new Dictionary<ValueLineType,                        Func<HtmlHelper,                             string,                             object,                             Type,                             string>>(); 

but not this other one with one extra parameter in the Func (the boolean):

public Dictionary<ValueLineType,                    Func<HtmlHelper,                         string,                         object,                         Type,                         bool,                          string>> constructor =         new Dictionary<ValueLineType,                        Func<HtmlHelper,                             string,                             object,                             Type,                             bool,                             string>>(); 

Either I’m getting blind or there’s something else I’m going to learn today 😀

Answer 1

There is no such thing as Func<T1,T2,T3,T4,T5,TResult>. It only goes as far as 4 parameters (i.e. 5 type parameters, including one for the return value):

Func<T> Func<T1, TResult> Func<T1, T2, TResult> Func<T1, T2, T3, TResult> Func<T1, T2, T3, T4, TResult> SpinalTap<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, TResult> 

You can declare your own, of course:

public delegate TResult Func<T1, T2, T3, T4, T5, TResult>     (T1 arg1, T2 arg2, T3 arg3, T4 arg4, T5 arg5); 

However, at that point I’d think really carefully about whether you might be able to encapsulate some of those parameters together. Are they completely unrelated?