| IsA questions [message #90551] |
Mon, 09 March 2015 17:03  |
Matthew Argall
Messages: 286
Registered: October 2011
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Senior Member |
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Why are an invalid objects and pointers not scalars?
IDL> print, size(1)
0 2 1
IDL> print, size(ptr_new())
0 10 1
IDL> print, size(obj_new())
0 11 1
IDL> print, isa(1, /SCALAR)
1
IDL> print, isa(ptr_new(), /SCALAR)
0
IDL> print, isa(obj_new(), /SCALAR)
0
How is the /STRING keyword different from setting Typename to "String"?
IsA('theString', 'String')
IsA('theString', /STRING)
Finally, is this confusing to anyone else? Why not a /DECIMAL keyword instead?
a = 1.0d
PRINT, ISA(a, /FLOAT) ; 1
PRINT, ISA(a, 'Float') ; 0
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| Re: IsA questions [message #90613 is a reply to message #90552] |
Tue, 17 March 2015 09:59  |
chris_torrence@NOSPAM
Messages: 528
Registered: March 2007
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Senior Member |
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On Monday, March 9, 2015 at 6:42:43 PM UTC-6, Matthew Argall wrote:
> I answered part of my own question... /STRING is to identify IDL_String classes. I guess the /INTEGER and /NUMBER keywords, then, would refer to the IDL_Integer and IDL_Number classes. And /FLOAT?
>
> e.g. http://exelisvis.com/docs/IDL_String.html
Hi Matthew,
I admit that there are some inconsistencies in the ISA results. For objects and pointers the idea was that ISA would return 0 for null object or pointers. However, I forgot about the /SCALAR keyword. I've fixed this for IDL 8.5, so ISA (with no keywords) will still return 0 for null heap variables, but will return 1 with /SCALAR.
The Typename argument refers to the actual IDL type (FLOAT or DOUBLE), as opposed to the FLOAT keyword, which can accept either float or double. Similarly for the COMPLEX keyword. DECIMAL might have been another choice, but would have been confusing for complex types...
I have also beefed up the Typename argument so it now accepts the "IDL_Variable" classes such as IDL_Integer, IDL_Number, and IDL_Variable.
Cheers,
Chris
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| Re: IsA questions [message #90619 is a reply to message #90617] |
Tue, 17 March 2015 15:22 |
chris_torrence@NOSPAM
Messages: 528
Registered: March 2007
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Senior Member |
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On Tuesday, March 17, 2015 at 1:16:13 PM UTC-6, Matthew Argall wrote:
> Thanks for the response! Am I right in assuming the behavior of /STRING is different from the "String" typename? I have IDL 8.2 so cannot actually test this. The documentation is not clear, either.
>
> Also, IDL assumes that any number that is not complex is purely real, so a REAL keyword could be used in combination with a DECIMAL keyword.
/STRING and "String" should be identical. I got tired of typing the quotes (and it seemed wasteful) so I added the keyword.
I'll think about REAL and DECIMAL, but at this point, I'll probably just let the dust settle for a while.
Thanks for the suggestions!
-Chris
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