25.3 Interactive Call

After the command loop has translated a key sequence into a definition, it invokes that definition using the function command-execute. If the definition is a function that is a command, command-execute calls call-interactively, which reads the arguments and calls the command. You can also call these functions yourself.

Function: commandp function

Returns t if function is suitable for calling interactively; that is, if function is a command. Otherwise, returns nil.

The interactively callable objects include strings and vectors (treated as keyboard macros), lambda expressions that contain a top-level call to interactive, compiled-function objects made from such lambda expressions, autoload objects that are declared as interactive (non-nil fourth argument to autoload), and some of the primitive functions.

A symbol is commandp if its function definition is commandp.

Keys and keymaps are not commands. Rather, they are used to look up commands (see Keymaps).

See documentation in Accessing Documentation, for a realistic example of using commandp.

Function: call-interactively command &optional record-flag keys

This function calls the interactively callable function command, reading arguments according to its interactive calling specifications. An error is signaled if command is not a function or if it cannot be called interactively (i.e., is not a command). Note that keyboard macros (strings and vectors) are not accepted, even though they are considered commands, because they are not functions.

If record-flag is the symbol lambda, the interactive calling arguments for command are read and returned as a list, but the function is not called on them.

If record-flag is t, then this command and its arguments are unconditionally added to the list command-history. Otherwise, the command is added only if it uses the minibuffer to read an argument. See Command History.

Function: command-execute command &optional record-flag keys

This function executes command as an editing command. The argument command must satisfy the commandp predicate; i.e., it must be an interactively callable function or a keyboard macro.

A string or vector as command is executed with execute-kbd-macro. A function is passed to call-interactively, along with the optional record-flag.

A symbol is handled by using its function definition in its place. A symbol with an autoload definition counts as a command if it was declared to stand for an interactively callable function. Such a definition is handled by loading the specified library and then rechecking the definition of the symbol.

Command: execute-extended-command prefix-argument

This function reads a command name from the minibuffer using completing-read (see Completion). Then it uses command-execute to call the specified command. Whatever that command returns becomes the value of execute-extended-command.

If the command asks for a prefix argument, it receives the value prefix-argument. If execute-extended-command is called interactively, the current raw prefix argument is used for prefix-argument, and thus passed on to whatever command is run.

execute-extended-command is the normal definition of M-x, so it uses the string ‘M-x ’ as a prompt. (It would be better to take the prompt from the events used to invoke execute-extended-command, but that is painful to implement.) A description of the value of the prefix argument, if any, also becomes part of the prompt.

(execute-extended-command 1)
---------- Buffer: Minibuffer ----------
1 M-x forward-word RET
---------- Buffer: Minibuffer ----------
     ⇒ t

Function: interactive-p

This function returns t if the containing function (the one that called interactive-p) was called interactively, with the function call-interactively. (It makes no difference whether call-interactively was called from Lisp or directly from the editor command loop.) If the containing function was called by Lisp evaluation (or with apply or funcall), then it was not called interactively.

The most common use of interactive-p is for deciding whether to print an informative message. As a special exception, interactive-p returns nil whenever a keyboard macro is being run. This is to suppress the informative messages and speed up the execution of the macro.

For example:

(defun foo ()
  (interactive)
  (and (interactive-p)
       (message "foo")))
     ⇒ foo

(defun bar ()
  (interactive)
  (setq foobar (list (foo) (interactive-p))))
     ⇒ bar

;; Type M-x foo.
     -| foo

;; Type M-x bar.
;; This does not print anything.

foobar
     ⇒ (nil t)