13.1: The History of Morphic

Morphic was developed by John Maloney and Randy Smith for the Self programming language, starting around 1993. Maloney later wrote a new version of Morphic for Squeak, but the basic ideas behind the Self version are still alive and well in Pharo Morphic: directness and liveness. Directness means that the shapes on the screen are objects that can be examined or changed directly, that is, by clicking on them using a mouse. Liveness means that the user interface is always able to respond to user actions: information on the screen is continuously updated as the world that it describes changes. A simple example of this is that you can detach a menu item and keep it as a button.

Bring up the World Menu and meta-click once on it to bring up its morphic halo, then meta-click again on a menu item you want to detach, to bring up that item’s halo. (Recall that you should set halosEnabled in the Preferences browser.) Now drag that item elsewhere on the screen by grabbing the black handle (see Figure \(\PageIndex{1}\)), as shown in Figure \(\PageIndex{2}\).

Figure \(\PageIndex{1}\): The grab handle.

Figure \(\PageIndex{2}\): Detaching a morph, here the Playground menu item, to make it an independent button.

All of the objects that you see on the screen when you run Pharo are Morphs, that is, they are instances of subclasses of class Morph. Morph itself is a large class with many methods; this makes it possible for subclasses to implement interesting behaviour with little code. You can create a morph to represent any object, although how good a representation you get depends on the object!

To create a morph to represent a string object, execute the following code in a Playground.

'Morph' asMorph openInWorld

This creates a Morph to represent the string 'Morph', and then opens it (that is, displays it) in the world, which is the name that Pharo gives to the screen. You should obtain a graphical element (a Morph), which you can manipulate by meta-clicking.

Of course, it is possible to define morphs that are more interesting graphical representations than the one that you have just seen. The method asMorph has a default implementation in class Object class that just creates a StringMorph. So, for example, Color tan asMorph returns a StringMorph labeled with the result of Color tan printString. Let’s change this so that we get a coloured rectangle instead.

Open a browser on the Color class and add the following method to it:

Color >> asMorph
    ^ Morph new color: self

Now execute Color orange asMorph openInWorld in a Playground. Instead of the string-like morph, you get an orange rectangle (see Figure \(\PageIndex{3}\))!

Figure \(\PageIndex{3}\): Color orange asMorph openInWorld with our new method.