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Re: Map Projection Bug [message #64722]

Thu, 15 January 2009 15:47

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Ed Hyer writes:

> Wow, this is really a tough one. Out of curiosity, I just did a quick
> scan through all the map_* routines in /idl/lib/, and I'm pretty
> confident that whatever is getting modified by the call to
> map_proj_init(), it's not a ! system variable. There was one
> suspicious line, 'suspicious' in that "I don't understand it." When
> creating a new MapStruct, it starts from !MAP, but does it like this:
>
> sMap = {!MAP}
>
> What means the curly braces?

Curly braces are how you create a structure. When IDL
creates a structure like this, it doesn't save the
instance data, rather it saves the *definition* of the
structure. So, the sMap variable is a structure of the
same type as the !MAP structure. This is what you would
expect.

What you *wouldn't* expect is that this variable, created
in one program, would change because of something you did
in some completely unrelated program!

Cheers,

David

--
David Fanning, Ph.D.
Coyote's Guide to IDL Programming (www.dfanning.com)
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: Map Projection Bug By: David Fanning on Thu, 15 January 2009 15:47
		Re: Map Projection Bug By: David Fanning on Thu, 15 January 2009 14:25
		Re: Map Projection Bug By: cgpadwick on Thu, 15 January 2009 13:21
		Re: Map Projection Bug By: pgrigis on Thu, 15 January 2009 12:43
		Re: Map Projection Bug By: MarioIncandenza on Thu, 15 January 2009 12:27
		Re: Map Projection Bug By: David Fanning on Thu, 15 January 2009 09:55
		Re: Map Projection Bug By: cgpadwick on Thu, 15 January 2009 09:01
		Re: Map Projection Bug By: R.Bauer on Fri, 16 January 2009 04:00

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