I am self-taught in LabView like most people in academic science, but the main VI I use has finally become sufficiently complex that I have to worry about memory management and other concepts that beginners don't normally worry about.
so I read the "LabVIEW Performance and Memory Management - Tutorial" http://zone.ni.com/devzone/conceptd.nsf/webmain/732CEC772AA4FBE586256A37005541D3?opendocument which was pretty informative. But the document brought up several questions regarding efficient memory management and style: 1. First, they tell you to avoid using complex data structures such as clusters, clusters of clusters, arrays of clusters, etc. But if you have a complex VI, you really have no choice. There's only so many terminals one can put on a sub-VI, and even if you could put more, you wouldn't want to have 100 wires sticking out. The tutorial tells you to do stuff like, have separate arrays of data of a single type. I can see how this is more efficient, but then when you want to pass one set of data (that would normally be in a cluster) to another VI , you have to index all N arrays, stuff them in a cluster, then put them into a sub-VI. That's hardly an optimal solution, coding wise, and more importantly, style-wise. I worry about style because, (a) I'm about to graduate, and I have to pass my code onto someone else, (b) it saves a lot of development time, and (c) my programming courses in college beat on style relentlessly. In the C and Java courses I have taken, I've always been taught to encapsulate data into logical data structures. It would seem that clusters are the analog of structs in C or objects in Java, and I'm sure there are plenty of very complex VI's out there that must use such data structures. <b>Is there a way to make cluster use more memory efficient?</b> Right now, I use references to clusters, but the "Memory Management" tutorial says that when you use attribute (property?) nodes in a Sub-VI, you then have to allocate memory in the Sub-VI for the front-panel controls referenced. So that would seem to defeat the purpose of using references to avoid making a copy of a complicated data structure. 2. The tutorial also says to avoid using local variables and instead use "data flow" programming, such as shift registers and continuous wires that go into, through, and out of loops. But, again, if you have complex program, you're going to have a ton of wires stretching across your VI, especially if you're not encapsulating your data in clusters. And you'd have to cross wires, which is apparently a big no-no. <b>So how do you use data flow programming wihtout making your VI impossible to read?</b> 3. <b> Is there a way to use LabView in a more object-oriented way?</b> LabView touts itself as being object-oriented, but it doesn't really let users take advantage of that. I can see that LabView and G itself is based on object-oriented code, but users can't really make their own objects and manipulate them as they can in C++ or Java. I realize that there are add-on packages you can buy, but it seems that they don't really give all the functionality of an Object Oriented language (e.g. interfaces, real polymorphism). It seems that at least some sort of ability to make objects and classes would let people clean up their code. Whether that overhead would increase memory use unacceptably is something the NI engineers would have to worry about. I guess the debate over performance vs. style is pretty general to all languages. 4. <b>Is there any way to learn good LabView style?</b> as mentioned before, most people in my field are self-taught. There haven't any LabView classes at the schools I've been to, and I don't have a lot of time to travel to or take the NI-sponsored classes. My and of my lab-mates' VI's are gawdawful messes of tangled wires. LabView the development environment doesn't really seem to force you to use some semblance of style like, say, Java does. I know the whole "wires go left to right" bit, but that only takes you so far, and I had been using LabView for 3 years before I found that one out. 5. I'm using LabView 6.1. <b>Is LabView 7 more memory/performance efficient?</b> Or do the new bells and whistles make it less efficient? In LabView 6.1 I've noticed that tab controls slow down things quite a bit. Anyway, if you have any answers or comments, I would appreciate your input.
