Stagg54

The application I'm thinking of is an error logger. Within each application there should only ever be one instance of the error logger and I don't want to pass an error logger wire through every vi in my application, hence the singleton makes sense. I would have a generic error logger class that would work in 90% of my applications. Perhaps that other 10% of the time I want to do add something else to the file or do something slightly different but almost all of the basic functions are the same. It wouldn't make sense to duplicate everything. I think it would make sense to be able to make a child class for that occasion. With this implementation, there doesn't appear to be any easy way to do that. Is there a better way to go than inheritance to achieve this? That doesn't seem so ridiculous to me. What if your program uses a DMM and at any given time there is only 1 DMM in the system. It would make sense to use a singleton. Now say that DMM could be one of 3 types, it could be Keithley, NI or some other brand. But each performs the same basic functions. It would make sense to have a subclass for each meter that inherits from the generic DMM. Am I thinking about this the wrong way? I'm kind of new to using classes but to me this seems to make sense. How would you solve a similar problem?

I like it. One issue I see that doesn't really seem to have a workaround is inheritance. I don't see how it could be done with this model, at least not easily.

Thanks for your responses. I will take all of that into consideration.

I'm curious if anyone has ever run into this before and how they deal with it. Here's my problem: I have 1 program that depending on which location/setting it is used in ( currently only 3 options here) it has a different front panel appearance (ie. BGcolor, text colors, boolean colors, plot colors, line styles, etc.) My world would be much easier if everyone could just agree, but that's not going to happen (which is good in a way because it keeps me employed.) Oh and also for each of these locations, when the user prints the screen I have to change all the controls to another appearance. I'm weighing a few options: As far as actually updating the control properties 1. I could do the brute force method and have a case structure in the init stage of every VI that is displayed and use proprty nodes to set every control/indicator based on which location/setting I am in. Not elegant at all but it works. Not exactly very expandable either. Everything is pretty much hardcoded unless maybe I read it in from an .ini file. Also a lot of duplicated code. If I have a particular graph that appears on 3 screens and is handled the same way, I have to repeat the code 3 times. Maybe I make a subvi - who knows. 2. I looked at xcontrols and having a method for each xcontrol something like set color scheme, but from what I can figure replacing all of the controls with xcontrols would be a complete waste of time. 3. The most promising appears to be using vi server because we have a splash screen that loads all of the VIs so when I load each one I can set the properties of each control using property nodes and references. 4. There has to be some way to incorporate classes and dynamic dispatching into method #3. As far as managing the different schemes: 1. I could read all the info from an ini file - seems straightforward 2. If I classes perhaps I could create a child class for each location and one for the print settings for each location. If anyone has any thoughts or ideas it would be nice. This seems like a pretty overwhelming problem and I'm just trying to wrap my brain around it. I figure no matter what it's going to take a lot of effort, but I figure any planning I can do ahead of time will really pay off in the end. Of course I'd like to come up with somehting that is readable, scalable, and maintainable. Knowing the people that I'm dealing with their liable to change their minds 20 times yet today about what colors they want and what line types, etc.