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Last modified: December 2006

URL: http://cxc.harvard.edu/ciao3.4/usage.tm.html
Hardcopy (PDF): A4 | Letter
AHELP for CIAO 3.4 usage Context: slangrtl

Synopsis

Generate a usage error

Syntax

usage (String_Type msg)

Description

The usage function generates a usage exception and displays msg to the message device.

Example

Suppose that some function plot plots an array of x and y values. The such a function could be written to issue a usage message if the wrong number of arguments were passed:

    define plot ()
    {
       variable x, y;

       if (_NARGS != 2)
         usage ("plot (x, y)");

       (x, y) = ();
       % Now do the hard part
          .
	  .
    }
Hardcopy (PDF): A4 | Letter
Last modified: December 2006



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