Impossible "If"

[Opus4]

It is hard to try telling what is going on from a small section of code. Try simplifying the code you are dealing with -- move most/all of the other branches to some temporary location so you have fewer branches/etc in the UI chain you are dealing with. Or, set up a test menu where you preconfigure some data to be sent to a simplified UI chain that consists of only the small portion of code you are trying to figure out.

And, confirm that you didn't put a similar-looking debug log statement somewhere else so it only looks like this one is getting executed.

- Andy

[GKusnick]

Originally Posted by tmiranda

I'm sure (as I can be) that it is being reached because I can see the output from the DebugLog() statement (see below) just before the If in the logfile.

But as I said, it's a multi-pass execution process and there are passes when those calls can get evaluated even on inactive branches of an If. Normally I'd expect to see several copies of that output for each screen refresh.

As Andy said, your best bet is to try isolating the troublesome code in a simple test case and see if still misbehaves.

[tmiranda]

I fixed the problem in a rather inelegant way; I deleted everything after the panel and started over. The "new" code is the same as the old code except it works.

I still have no clue why it didn't work before. I printed the old code and copied it line for line.

Go figure.

Tom

[Tiki]

I was actually going to suggest that... go figure.

Did you by chance save the "corrupt" STV file?

It may be worth doing a comparison (either with the comparison tools inside Studio, or by doing a direct text compare of the XML files), just to see what's different (must be something in the XML code that's not showing up in Studio).

[tmiranda]

Tiki,

I didn't save anything, except my sanity. I'm trying to finish updating the Phoenix Fanart for Default STVi to support Genres and actors. I really like your BMITools STVi and have extended that a bit to show Genre fanart, hope you do not mind me building on your work AGAIN.

Tom

[tmiranda]

Originally Posted by GKusnick

The rules for Ifs in blue UI code are a bit unintuitive. The entire tree, included all branches, gets evaluated at menu load time to instantiate the UI components. There are then additional passes for layout and rendering, during which only active branches get evaluated. So you'll sometimes see debug output triggering at unexpected times that might lead you to think a branch is active when it really isn't.

Greg,

Can you explain this a little further? What are "the rules" in the UI widget chain? How many passes are there and what happens on each pass? Are the passes the same regardless of platform (Windows, Linux, Client, Extender, PlaceShifter)? Where can I find out more about this?

I think this may have bitten me in the rear more than once so I'd like to understand it better.

Thanks,

Tom

[GKusnick]

Originally Posted by tmiranda

What are "the rules" in the UI widget chain? How many passes are there and what happens on each pass? Are the passes the same regardless of platform (Windows, Linux, Client, Extender, PlaceShifter)? Where can I find out more about this?

The Debug menu in Studio will give you some idea of what the various passes are about. My own knowledge (such as it is) is based primarily on that. So your best option is probably to construct some simple examples and then turn on tracing to observe the resulting execution flow.

[razrsharpe]

a rule of thumb that i live by is to the LEAST amount of processing in the UI Chain. In fact i try to only do UI related processing / decisions in the UI chain. All my data crunching is done in "Green" process chains. Doing this makes your menu run that much speedier bc "Green" chains only get executed once...

Here is a small test stv i wrote to illustrate how many times the UI chain gets executed.

[tmiranda]

Gents,

Thank you all for the help. I found the root cause of the problem was having too much execution logic in the UI widget chain. I moved as much as possible to a BeforeMenuLoad hook and all of the wierdness went away. It also made the UI much snappier as razr pointed out.

Chalk that up as another lesson learned the hard way

Tom