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GNU Info (emacs-lisp-intro.info)Args as Variable or ListAn Argument as the Value of a Variable or List ---------------------------------------------- An argument can be a symbol that returns a value when it is evaluated. For example, when the symbol `fill-column' by itself is evaluated, it returns a number. This number can be used in an addition. Position the cursor after the following expression and type `C-x C-e': (+ 2 fill-column) The value will be a number two more than what you get by evaluating `fill-column' alone. For me, this is 74, because the value of `fill-column' is 72. As we have just seen, an argument can be a symbol that returns a value when evaluated. In addition, an argument can be a list that returns a value when it is evaluated. For example, in the following expression, the arguments to the function `concat' are the strings `"The "' and `" red foxes."' and the list `(number-to-string (+ 2 fill-column))'. (concat "The " (number-to-string (+ 2 fill-column)) " red foxes.") If you evaluate this expression--and if, as with my Emacs, `fill-column' evaluates to 72--`"The 74 red foxes."' will appear in the echo area. (Note that you must put spaces after the word `The' and before the word `red' so they will appear in the final string. The function `number-to-string' converts the integer that the addition function returns to a string. `number-to-string' is also known as `int-to-string'.) automatically generated by info2www version 1.2.2.9 |