Name

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  SetDefaultValue

Purpose

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  This procedure sets default values for positional and keyword arguments to
  IDL procedures and functions.

Author

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  FANNING SOFTWARE CONSULTING
  David Fanning, Ph.D.
  1645 Sheely Drive
  Fort Collins, CO 80526 USA
  Phone: 970-221-0438
  E-mail: david@idlcoyote.com
  Coyote's Guide to IDL Programming: http://www.idlcoyote.com/

Category

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  Utilities

Calling Sequence

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  SetDefaultValue, argument, defaultValue

Arguments

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  argument: The augument variable you are setting the default value of. If this variable
                  is undefined, the defaultValue will be assigned to it. Otherwise, the argument
                  variable will not change.
                 
  defaultValue: The default value that will be assigned to the argument variable ONLY if the argument
                  variable is undefined. If this variable is undefined, the argument variable will
                  be treated as if the BOOLEAN keyword had been set.

Keywords

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  BOOLEAN: If this keyword is set, the argument value will always be forced to return with a
                  value of 0 or 1.

Example

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  FUNCTION Action, arg1, arg2, MULTIPLY=multiply
 
    SetDefaultValue, arg1, 1
    SetDefaultValue, arg2, 2
    SetDefaultValue, multiply, 1, /BOOLEAN
   
    IF multiply THEN RETURN, arg1 * arg2 ELSE RETURN, arg1 + arg2
   
  END

Modification History

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  Written by: David W. Fanning, November 26, 2008, from suggestion by Carsten Lechte on
    IDL newsgroup on this date.
  Made a change to the way the BOOLEAN keyword works. Now argument is set to BOOLEAN before
    return, if required. 3 Dec 2008. DWF.