Page 267	Table of Contents	Index	Page 269
	Chapters
	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 A, B, C, D, E

---

CHAPTER 27. COMMAND PROCESSING

• :default value, where value is the default that should be used for the argument, as for
  accept.
  
  
• :default-type is the same as for accept.
  
  
• :display-default is the same as for accept.
  
  
• :mentioned-default value, where value is the default that should be used for the argument
  when a keyword is explicitly supplied via the command-line processor, but no value is
  supplied for it. :mentioned-default is only allowed on keyword arguments.
  
  
• :prompt string, where string is a prompt to print out during command-line parsing, as for
  accept.
  
  
• :documentation string, where string is a documentation string that describes what the
  argument is.
  
  
• :when form. form is evaluated in a scope where the parameter variables for the required
  parameters are bound, and if the result is nil, the keyword argument is not available.
  :when is only allowed on keyword arguments, and form cannot use the values of other
  keyword arguments.
  
  
• :gesture gesture, where gesture is either a pointer gesture name or a list of a pointer
  gesture name followed by keyword-value pairs. When a gesture is supplied, a presentation
  translator will be defined that translates from this argument's presentation type to an
  instance of this command with the selected object as the argument; the other arguments
  will be filled in with their default values. The keyword-value pairs are used as options for
  the translator. Valid keywords are :tester, :menu, :priority, :echo, :documentation,
  and :pointer-documentation. The default for gesture is nil, meaning no translator will
  be written. :gesture is only allowed when the :command-table option was supplied to
  the command-defining form.

body implements the body of the command. It has lexical access to all of the commands argu-
ments. If the body of the command needs access to the application frame itself, it should use
*application-frame*. The returned values of body are ignored. body may have zero or more
declarations as its first forms.

define-command must arrange for the function that implements the body of the command to
get the proper values for unsupplied keyword arguments.

name-and-options and body are not evaluated. In the argument descriptions, the parameter
variable name is not evaluated, and everything else is evaluated at run-time when argument
parsing reaches that argument, except that the value for :when is evaluated when parsing reaches
the keyword arguments, and :gesture isn't evaluated at all.

27.2 Command Tables

There are four main styles of interaction: keyboard interaction using a command- line processor,
keyboard interaction using keystroke accelerators, mouse interaction via command menus, and

---

Page 267	Table of Contents	Index	Page 269
	Chapters
	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 A, B, C, D, E