| Re: overload init function in class/object ? [message #34984 is a reply to message #34982] |
Tue, 06 May 2003 13:26   |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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paul wisehart (wisehart@runbox.com) writes:
> (So technically speaking you _cannot_ overload functions in
> IDL? You just use optional parameters to get the same effact?)
Isn't that a distinction without a difference?
When your parameters can be anything you would like
them to be, and you can have as many as you like,
what else could possibly be meant by "overloading".
Here is code for a GETCOLOR method on my ColorTool object.
The variable theColor can be absent, a scalar string, or a
string array. The variable colorIndex can be absent, a
scalar, or an array.
FUNCTION ColorTool::GetColor, theColor, colorIndex, $
AllColors=allcolors, $
Cancel=cancelled, $
Decomposed=decomposedState, $
_Extra=extra, $
Names=names, $
Row=row, $
Triple=triple, $
_Extra=extraKeywords
@cat_error_handler
; Make sure you have a color name and color index.
CASE N_Elements(theColor) OF
0: BEGIN
theColor = 'White'
IF N_Elements(colorIndex) EQ 0 THEN $
colorIndex = !P.Color < (!D.Table_Size - 1) $
ELSE colorIndex = 0 > colorIndex < (!D.Table_Size - 1)
ENDCASE
1: BEGIN
type = Size(theColor, /TNAME)
IF type NE 'STRING' THEN $
Message, 'The color must be expressed as a color name.'
IF N_Elements(colorIndex) EQ 0 THEN $
colorIndex = !P.Color < (!D.Table_Size - 1) $
ELSE colorIndex = 0 > colorIndex < (!D.Table_Size - 1)
ENDCASE
ELSE: BEGIN
type = Size(theColor, /TNAME)
IF type NE 'STRING' THEN $
Message, 'The colors must be expressed as color names.'
ncolors = N_Elements(theColor)
CASE N_Elements(colorIndex) OF
0: colorIndex = Indgen(ncolors) + $
(!D.Table_Size - (ncolors + 1))
1: colorIndex = Indgen(ncolors) + colorIndex
ELSE: IF N_Elements(colorIndex) NE ncolors THEN $
Message, 'Index vector must be the same ' + $
'length as color name vector.'
ENDCASE
ENDCASE
Cheers,
David
--
David W. Fanning, Ph.D.
Fanning Software Consulting, Inc.
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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