setdefaultvalue.pro
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; docformat = 'rst'
;
; NAME:
; SetDefaultValue
;
; PURPOSE:
; This procedure sets default values for positional and keyword arguments to
; IDL procedures and functions.
;
;******************************************************************************************;
; ;
; Copyright (c) 2008, by Fanning Software Consulting, Inc. All rights reserved. ;
; ;
; Redistribution and use in source and binary forms, with or without ;
; modification, are permitted provided that the following conditions are met: ;
; ;
; * Redistributions of source code must retain the above copyright ;
; notice, this list of conditions and the following disclaimer. ;
; * Redistributions in binary form must reproduce the above copyright ;
; notice, this list of conditions and the following disclaimer in the ;
; documentation and/or other materials provided with the distribution. ;
; * Neither the name of Fanning Software Consulting, Inc. nor the names of its ;
; contributors may be used to endorse or promote products derived from this ;
; software without specific prior written permission. ;
; ;
; THIS SOFTWARE IS PROVIDED BY FANNING SOFTWARE CONSULTING, INC. ''AS IS'' AND ANY ;
; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES ;
; OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT ;
; SHALL FANNING SOFTWARE CONSULTING, INC. BE LIABLE FOR ANY DIRECT, INDIRECT, ;
; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED ;
; TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; ;
; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ;
; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ;
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS ;
; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ;
;******************************************************************************************;
;
;+
; This procedure sets default values for positional and keyword arguments to
; IDL procedures and functions.
;
; :Categories:
; Utilities
;
; :Params:
; argument: in, required
; 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: in, required
; 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:
; boolean: in, optional, type=integer
; If this keyword is set, the argument value will always be forced to return with a
; value of 0 or 1.
; range: in, optional
; A two-element array that gives the accepted range of the variable. The output argument
; will be forced into this data range: range[0] > argument < range[1].
;
; :Examples:
; Here is how to use this program::
;
; 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
;
; :Author:
; FANNING SOFTWARE CONSULTING::
; David W. Fanning
; 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
;
; :History:
; Change History::
; 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.
; Added RANGE keyword. 22 March 2014. DWF.
;
; :Copyright:
; Copyright (c) 2008-2014, Fanning Software Consulting, Inc.
;-
PRO SetDefaultValue, argument, defaultValue, RANGE=range, BOOLEAN=boolean
; Return to the caller if there is an error.
On_Error, 2
; We only need change if the argument is undefined.
IF N_Elements(argument) EQ 0 THEN BEGIN
; If the default value is undefined, treat as BOOLEAN.
; Otherwise, assign default value to the argument.
IF N_Elements(defaultValue) EQ 0 THEN BEGIN
argument = Keyword_Set(argument)
ENDIF ELSE BEGIN
argument = defaultValue
ENDELSE
ENDIF
; Require boolean.
IF Keyword_Set(boolean) THEN argument = Keyword_Set(argument)
; Confine to a range?
IF N_Elements(range) NE 0 THEN BEGIN
argument = range[0] > argument < range[1]
ENDIF
END ;-----------------------------------------------------------------------------------------