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This technique is called polymorphism, and it is arguably the most powerful aspect of object-oriented programming. It calls this function for every point on the grid, giving it the point object for that point as its first argument, and the value that is on the grid at that point as second argument.
Now those were games!
An expression such as this one can be used to reliably work around this:. We already saw simple examples of this, like the toString method on objects. This will not work. Instead of adding arguments to a function, this one adds a this object, using the first argument to the function’s apply method: Every object has a method called hasOwnPropertywhich tells us whether the object has a property with a given name.
The ‘reached list’ we used at the end of chapter 7 is an example of this: When using new on this constructor, it will create a new object based on the given object. When a program is not ‘truly object-oriented’, whatever that means, it is considered decidedly inferior.
Unless someone actually javascrlpt.programowanie with the method in Object. Otherwise, if there is space to move, it moves into a random nearby empty square. Unless you are very lucky, the lichen-eaters will probably still go extinct after a while, because, in a time of mass starvation, they crawl aimlessly back and forth through empty space, jvascript.programowanie of finding the lichen that is sitting just around the corner.
Here is a constructor for rabbits:. In this case there is not much harm done, but there are situations where this would cause a problem. We could of course just type [“n”, jvaascript.programowanie, This can be solved by doing something even uglier: For one thing, our killerRabbit has a property called constructorwhich points at the Rabbit function that created it.
To make this easy, we can use a higher-order javasscript.programowanie that takes an action as its argument. The terrarium merely provides the infrastructure that asks them what to do every half second, and if they decide to move, it makes sure this happens. Instead of providing regular functions for working with the objects, they provide a way to create such objects, using the new keyword, and a number of methods and properties that provide the rest of the interface. That is not very practical.
For example, a piano also has pedals.