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Like a real wall, it doesn’t do much, it just sits there and takes up space.
Instead of adding arguments to a function, this one adds a this object, using the first argument to the function’s apply method:. In this case there is not much harm done, but there are situations where this would cause a problem.
Some problems are best solved by building a complex family tree of types. Try to find a way to make it fit in the ecosystem without dying out too quickly.
SmallItem can be seen as such a prototype. Give the lichen-eater “c” as its character pac-man.
A function is called as a method when it is looked up as a property, and immediately called, as in object. There will be some objects involved this is, after all, the chapter on object-oriented programming. It would be nicer if it would print automatically.
Instead of adding arguments to a function, this one adds a this object, using the first argument to the function’s apply method: Sure, duplicating the line is shorter than calling the Item. It means that using an object to store a set of things, such as the cats from chapter 4can go wrong. For one thing, our killerRabbit has a property called constructorwhich points at the Rabbit function that created it.
This time, we will use a constructor and two methods. Inheritance is best used when the thing modelled by the sub-type can be said to be an object of the super-type. To make this easy, we can use a higher-order function that takes an action as its argument.
It takes one argument, the point at which the bug is currently standing, and returns an object with information about the surroundings of that point. Objects play both the role of ‘values with methods’, for which prototypes work great, and ‘sets of properties’, for which prototypes only get in the way. In this case, we need to represent a grid of values, so I wrote a Grid type, which supports the operations that the terrarium will need.
You give it the object on the left hand side, and a constructor on the right hand side, and it returns a boolean, true if the constructor’s prototype property is the direct or indirect prototype of the object, and false otherwise. One can use an array of arrays, like this: Now those were games!
There is one more catch, however.