OK to put text widget at end to make UI chain complete?

[tmiranda]

Is it OK to stick a text widget at the end of a widget chain in order to complete a UI chain? In my code I am checking for various error conditions and if they exist I want to write a DebugLog() message. The problem is if a UI chain does not have a UI widget at the end it doesn't get executed. To get around this I've been putting a text widget at the end of the chain. Am I asking for trouble?

Here is mock-up example:

If expression=x
   Display some image on the UI
else if expression=y
  Display some other image on the UI
else if expression=z
   DebugLog("This should never occur.")
      Text Widget Here

This seems to work with no adverse side-effects but I want to make sure I'm not going to break something down the road.

[PLUCKYHD]

Don't know about any side effects.. I have some debugs in the ui as part of a chain but display pictures and such after it.

I don't understand why you have it part of the ui if you are not drawing anything or displaying anything ??

[tmiranda]

It's error checking. If I get to one of these places it is because there is nothing to display but there should be. If I had an image to display I would

[GKusnick]

Using dummy text widgets does work, and I've resorted to it once or twice myself, but I don't like doing it and usually try to look for a better way of structuring the code that makes it unneccesary. The thing is that those unreachable text widgets aren't free; they do get instantiated when the menu is loaded, but never actually get drawn on screen (unless execution reaches there somehow). So if you make a habit of this, you could end up larding up your UI with a lot of invisible junk.

In your example I'd probably be inclined to do the error checking before entering the If:

DebugLog(If(expression == z, "error", "OK"))
  If expression ...

or perhaps

mypackage_myclass_Assert(expression != z)
  If expression ...

where the Assert function prints out an error and/or throws an exception if the passed-in argument is false. This is a very common error-checking idiom in software engineering. Asserting pre- and post-conditions on a function or block of code lets you combine runtime error checking with a clear, human-readable statement of the input/output contract of that block.

By the way, you're not obliged to keep writing "else if expression==". An If widget also works like a case statement, which is what you want in your example:

If expression
  > x
    ...
  > y
    ....
  > else
    error

[tmiranda]

Thanks Greg. I knew how to create a case statement (my example was a poor choice) but I did not think about error handling in that way. Very slick. I've got to stop thinking like an assembler programmer ans start thinking like a java programmer.