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Re: The problem with bindings
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Re: The problem with bindings

On 29 Jul 2004, at 14:13, Drew McCormack wrote:

I'm no bindings layer expert, but the little time I have spent using them, I have found them quite difficult to grasp. Much more so than the outlet-target approach.

I make extensive use of bindings in FontFX7, and hadn't tried them before. There was a hurdle to get over in understanding how they work, but once I got over that it was really easy.

The only difficulty I had was understanding how to design my data model. I'd been using structs to structure my data, and that's a no-no with bindings, so I had to do a bit of a redesign.

I usually find that if things go well with bindings, I really can save that '300 lines of code' that everyone talks about, but when things go wrong, I can spend hours tracking down the problems, effectively negating any benefit I may have gained.

Usually when something goes wrong with my bindings it's because I've bound to the wrong thing, or my NSObjectController instance has a key spelt wrong.

Furthermore, easy things, like populating a table view with values, are well documented, and can be achieved very efficiently with bindings. But try to go a bit deeper, and do something not in the manual, and it requires a considerable commitment.

I did find the documentation slightly confusing to start, but there's a few good examples out there of how to do some slightly more difficult stuff. mmalc's produced some great bindings examples.

It's important to remember that bindings alone might not provide a complete solution. Making use of methods within your data model to produce derived values is a very handy technique which complements bindings. Also remember that bindings is built on KVC and KVO - you can make use of these things to help your bindings do more complex things. I really like KVO - all the derived parts of my data model are generated with KVO. Value transformers are also a handy thing to get to know.

Basically, it comes down to this: bindings are very hard to debug. You can't set a breakpoint, so you are left guessing at what is happening based on an obscure error message from an exception thrown deep in the Cocoa frameworks. Anyone else have this problem?

The question in my mind here is what is there to debug?

I've never had the bindings system itself crash on me. As I said above the problems I usually faced have been simple problems in my UI definition. Otherwise my problems have been with my data model, and those can be resolved with putting breakpoints inside the appropriate setter methods.

Steve
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 >The problem with bindings (From: Drew McCormack <email@hidden>)



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