Binding Commands

Epsilon lets you redefine the function of nearly all the keys on the keyboard. We call the connection between a key and the command that runs when you type it a binding.

For example, when you type the <Down> key, Epsilon runs the down-line command. The down-line command, as the name suggests, moves the point down by one line. So when you type the <Down> key, point moves down by one line.

You can change a key's binding using the bind-to-key command. The command asks for the name of a command, and for a key. Thereafter, typing that key causes the indicated command to run. Using bind-to-key, you could, for example, configure Epsilon so that typing <Down> would run the forward-sentence command instead of the down-line command.

This key-binding mechanism provides a great deal of flexibility. Epsilon uses it even to handle the alphabetic and number keys that appear in the buffer when you type them. Most of the alphabetic and number keys run the command normal-character, which simply inserts the character that invoked it into the buffer.

Out of the box, Epsilon comes with a particular set of key bindings that make it resemble the EMACS text editor that runs on many kinds of computers. Using the key-binding mechanism and the bind-to-key command, you could rearrange the keyboard to make it resemble another editor's keyboard layout. That is exactly what the brief-keyboard command does; it rearranges the keyboard commands to make Epsilon work like the Brief text editor. See Brief Emulation.

Epsilon provides over 400 commands that you can bind to keys, and you can write brand new commands to do almost anything you want, and assign them to whatever keys you choose. See Bindings for more information on the bind-to-key command.

Some commands have no default binding. You can invoke any command, bound or not, by giving its name. The command named-command, normally bound to Alt-x, prompts for a command name and executes that command. For example, if you type

Alt-x down-line

followed by pressing the <Enter> key, the cursor moves down one line. Of course, you would find it easier in this example to simply type the <Down> key.

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