A 2 minutes story written on Aug 2014 by Adrian B.G.

Testing the Medium editor and my first post about Unity Game Engine.

Problem

You have a script that generates something (ex a grid tile, a set of flying elves or goblin space shuttles) at run-time. Usually you write code, save, run the project, , see the results .. <repeat process>. You can take a shortcut and run code in editor too, saving time and energy.

Solution

Use [ExecuteInEditMode] You should read the documentation first http://docs.unity3d.com/ScriptReference/ExecuteInEditMode.html

Usually I want my code to be executed manually (not at every Update()) so I will use a trigger (a public bool variable) that will tell the script to execute when I’m ready (see C# example).

using UnityEngine;  
......  
[**ExecuteInEditMode**]  
public class TileGenerator : MonoBehaviour {``.......``public bool **restartLevel** = false;``void Start () {  
				this.restartLevel = true;  
	}  

	// Update is called once per frame  
	void Update () {  
//this is how you can run specific code	  
		if ( Application.isEditor){  
			InitPrefabs();  
		}  
	if ( **restartLevel** ){  
			restartLevel = false;  
			this.GenerateLevel();  
		}  
	}``/// <summary>  
	/// Draws all the tiles from this level and remove the old ones.  
	/// </summary>  
	void GenerateLevel(){  
.....magic code....  
	}

The variable must be public in order to control it’s state from an Inspector. Usually I make a special tiny Inspector window, locked, in a screen corner, so I can easily regenerate the current level / scene.

Pro advice: You can assign a custom key for this operation see Unity Doc — MenuItem ( like ctrl+r ) if you prefer the keyboard.

Image from ode2308