The Logo Editor

The pages that you will have read on defining procedures do not tell you how to get into or out of the editor in the particular version of LOGO you are using. This page is intended to help users of Logo PLUS and Terrapin Logo for the Mac.

Getting into the editor

There are a couple of basic methods if you are defining new procedures:

  1. Select Open Edit Window in the File menu (or hit <command> E )

  2. In the Logo window, type: to some.procedure.name
    (substituting the name of the procedure you wish to define for some.procedure.name)
In both cases the Edit window will open but, in the second case, the first line of the definition will be set up for you.

When you have some procedure(s) already defined and wish to edit it (them), you can also get into the Edit window from the Logo window by typing:

edit "some.procedure.name or edit [some list of procedure names]

This brings the procedure(s) into the Edit window, opening the window if need be.

edall is another useful tool (a primitive procedure) which brings all user-defined procedures, and variables too, into the Edit window.

Inside the editor

Once inside the editor, you will find that it behaves just like a simple text editor. There are only a couple of Logo specific features that you need to remember.

Firstly, a <return> marks the end of a Logo line. If you keep on typing and the line wraps around on the screen, you are still - despite appearances - in the same Logo line. If, for cosmetic reasons, you want to split a Logo line across more than one screen line, you can do this by using <tab>. The display - at least in Logo PLUS - will record the fact that the Logo line continues by placing an arrow symbol where you have made the break. Remember that you cannot split a Logo instruction across two Logo lines.

Secondly, procedure definitions end with a line containing the single word end. If you have just one procedure definition in the editor window and escape (see below), Logo is kind enough to pop in the end which you omitted. But don't try this when you have more than one definition in the editor - for obvious reasons - and it is probably a good idea to avoid the habit anyway.

Escaping from the editor

To define new procedures that you have created in the Edit window (or to re-define old procedures that you have edited), you must hit <enter> (not <return>) when you are ready. You will then be transported back to the Logo window where you will see one or more messages of the type:

PROCEDURE.NAME defined

Notice that you can literally escape from the Edit window, by accident as well as by design, merely by clicking on the Logo window. This brings the Logo window to the front and makes it the active window. If you do this, however, Logo will completely ignore what you have typed in the Edit window. In other words, the Edit window is treated just like a scratch pad until you explicitly ask Logo to look at it by hitting <enter>.

Using the Logo and Edit windows together

You will probably find it most convenient to have both the Edit and the Logo windows open at the same time and to expand them both to almost full screen size. Place one slightly to the left and one slightly to the right so that you can always see a little of the background window. In this way it is easy to bring either window to the front simply by clicking on it.

Happy editing!


Ron Brasington
Department of Linguistic Science
The University of Reading
Reading
UK

E-mail: ron.brasington@rdg.ac.uk