Recursive call with anonymous function
Sunday, October 29th, 2006Whether you want to generate a dynamic function, write a dynamic algorithm or want to handle delegate inline, anonymous functions have always been at your service. However one area where in anonymous function lacking is, making a recursive call. Since it does not have function signature it’s not possible to make recursive call, at lease not directly. This entry shows you how to achieve that by utilizing some reflection API. Yes reflection, it’s always been there as your lifeguard ;).
   To understand the concept lets first create a simple recursive function to find a triangle.
Code: public int Triangle(int n)
{
return (n==1) ? 1 : n + Triangle(n-1);
}
{
return (n==1) ? 1 : n + Triangle(n-1);
}
Now we will use anonymous function to find a triangle. Please notice the code. It performs following steps to achive recursion.
- First finds the current performing method using top frame in the StackTrace.
- And then invokes it.
Code:
public delegate int TriangleDelegate(int n); public static int AnonymousMethodTriangle(int n)
{
TriangleDelegate triangle = delegate(int n)
{
//Find Method
MethodBase method =
new StackTrace().GetFrame(0).GetMethod();
return (n == 1) ? 1 : n +
(int)method.Invoke(null,new object[]
{n-1});//Invoke Method
};
return triangle(n);
}
public delegate int TriangleDelegate(int n); public static int AnonymousMethodTriangle(int n)
{
TriangleDelegate triangle = delegate(int n)
{
//Find Method
MethodBase method =
new StackTrace().GetFrame(0).GetMethod();
return (n == 1) ? 1 : n +
(int)method.Invoke(null,new object[]
{n-1});//Invoke Method
};
return triangle(n);
}
Pretty simple huh….