Writing custom C# tasks for FAKE

"FAKE - F# Make" is intended to be an extensible build framework and therefor it should be as easy as possible to create custom tasks. This tutorial shows how to create a (very simple) custom task in C#.

Creating a custom task

Open Visual Studio and create a new C# class library called my MyCustomTask and create a class called RandomNumberTask:

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using System;

namespace MyCustomTask
{
  public class RandomNumberTask
  {
    public static int RandomNumber(int min, int max)
    {
      var random = new Random();
      return random.Next(min, max);
    }
  }
}

Using the custom task

Compile the project and put the generated assembly into the tools/FAKE path of your project. Now you can use your CustomTask in the build script:

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// include Fake libs
#I @"tools\FAKE"
#r "FakeLib.dll"

// include CustomTask
#r "MyCustomTask.dll"
open Fake 

// open CustomNamespace
open MyCustomTask

// use custom functionality
RandomNumberTask.RandomNumber(2,13)
  |> tracefn "RandomNumber: %d"

If you want to use FAKE's standard functionality (like globbing) within your CustomTask project, just reference FakeLib.dll and explore the FAKE namespace.