| Re: sharing information across widget hierarchies [message #72100] |
Mon, 09 August 2010 18:28 |
penteado
Messages: 866
Registered: February 2018
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Senior Member
Administrator |
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On Aug 6, 11:23 pm, Chris <beaum...@ifa.hawaii.edu> wrote:
> Ok, I can get around this by attaching the _same_ event function to
> widgets 2 and 3. Now at least a single function gets called whenever
> an event happens; but there's no single widget in which to store state
> information. So then I have to store the state information as a
> _pointer_ in the uvalue to widgets 2 and 3. This means that I'm
> constantly dereferencing the state information pointer, which is much
> more awkward (syntactically) than working with a single, non-pointer
> variable (does anyone else hate how ugly x =
> (*(*state_ptr).big_array_ptr)[first_col, *] looks?)
With IDL 8, you can both have simpler code and only pass around a
reference, using a hash instead of a structure. This removes two
levels of indirection: the one used to pass a pointer instead of
copying the structure, and the other to have dynamic fields in it. For
instance, the fragment above could be just
(state_hash['big_array'])[first_col,*]
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| Re: sharing information across widget hierarchies [message #72101 is a reply to message #72100] |
Mon, 09 August 2010 18:15  |
Robbie
Messages: 165
Registered: February 2006
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Senior Member |
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I'd say that if your widget is much more complicated than a few text
boxes then you should always use a pointer or object to store the
program state. Using a pointer means that you can get your data into
the place where you want it, without copying it. Whatever you might
loose with poor syntax, you gain with code re-use.
Robbie
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