ShaunR

Of course you can change or delete them. You just need to "deprecate" them first (which to me you should always do anyway). If I have defined them as protected it's not my problem if their code breaks child classes. They have made a conscious decision to override my bullet proof one for whatever reason sounds sane in their mind, so they should be aware of the consequences. You haven't changed anything (and don't try to bring public in as an equivalent - it's not). Similarly to my previous paragraph, they should understand what the consequences are since they understand why they are doing it. By making it private you are denying them the opportunity to add, in your example, logging to that accessor. So. What will they do? Hack your code! When it finally all falls to pieces three weeks later after they have forgotten about the hack and they have put in a bug report for your class (which you won't be able to replicate) you will eventually find that out if/when they send the code. You don't stop them from doing anything by making it private. What you do is force them to modify your code to make it fit their use case. Bear in mind also. It is only rare occasions when it is required, but the argument is that if they wish to do so, however unsavory it may be, then they should be able to without modifying the original, tested code. Then it's their problem not yours.

Personally? More the latter (but I have heard reasonable arguments for the former). For example. In languages where you declare the scope of variables, then it's imperative to define variables that maintain state as private (this restricts creating debugging classes). Methods, on the other hand, should generally be protected so that the you don't restrict the ability to affect behaviour and I have never seen *(or can think of any) reason why any should be private. Even those that the developer sees as private "may" be of use to a downstream developer. I think that here we fundamentally disagree. There is only "re-use"; one "instance", if you like. Can it be re-used without modification. Re-purposing without modification goes a long way towards that and the more restrictions, the less it can be re-purposed. One is aimed at the user, the other at downstream developers but they are not in opposition (we are not looking at Public Vs Private). When re-purposed, you (as the designer) have no idea of the use-case regardless of what you "intended". Suffice to say a developer has seen a use case where your class "sort of" does what he needs, but not quite. Placing lots of restrictions just forces down-stream developers to make copies with slight modifications and that is an anathema to re-use.As for "ease of use". Well. That is subjective. What is easy for you may not be easy for me especially if it is a use-case that was conceived when your crystal ball was at the cleaners

This is also the crux of the Private Vs Protected debate. What is it better to do? Put so many restrictions that they have to edit your code for their use case (and you will get all the flack for their crap code), or make it easy to override/inherit so they can add their own crap code without touching your "tested to oblivion" spaghetti - regardless of what you think they should or shouldn't do.

If you want to test to see what the interface can handle. You can benchmark (and open lots of connections) with Dispatcher.

Nowadays I use a DB file for settings which means you can mutate from version to version with a single, non application specific, query and do other stuff like revert to defaults without having to write application specific code. I'm also leaning further towards having a single "config" DB file for all applications which works great especially if you have multiple applications (it's like using the windows registry, but works on all platforms and you can copy it!). You can do something similar with INI files and have global INI directory somewhere outside your applications (as bmoyer is suggesting) which has a sub-directory structure with the app name and version. Loading and saving is just a matter of building a path using the App name and version (i.e. non-application specific). This doesn't get around mutation, but it means that if you un-install or re-install you can always get to the same point as you, in effect, build up a history even if they delete the entire application directory.

I'd have a look at the icon editor. It can overlay the connector so it must get it somehow.

You weren't going mad. I got it too on all the threads so I couldn't post that there was a problem

OK. Played a bit more with yours and Rolfs comments in mind. I will modify my original statement to Dynamic libraries, however, still are no-where as bad as diagram-less VIs (LabVIEW dynamic libraries being slightly worse from a deployment perspective than C ones, it seems.).

I think you'll find that "linking" has a very specific meaning for GPL licencing rather than "connecting" which is probably what you are thinking (and what ADO facilitates).

Can you expand on that since that has not been my experience. Are we talking about MSVC dependency linking being the reason or is there something else. ......later, after playing a bit...... So that's pretty definitive. It looks like it checks. But I would still like to understand what the issues are i.e. what makes a LabVIEW dll different from a C dll apart from feature support

I think I ought to clarify this. I assume you came to this conclusion from Rolfs comparison with panel-removed VIs. It's not actually as bad as that, Dynamic libraries in themselves aren't so much version specific but they are platform specific. A dynamic library can be loaded in any version of LabVIEW with a caveat. IF the library was written purely in C. You could load it in any version of LabVIEW and you wouldn't need the LV run-time for non-LabVIEW users (this you know). If you create the library using the LabVIEW build process, then the user should have that version of the run-time. The main reason for this, however, is more to do with the supported features that you may put in the dynamic library rather than the compilation process (although NI tends to use different compilers with each version - so it is also a safer bet for that reason). Therefore it is possible to load a LabVIEW 2009(32 bit,) built library in an executable built in LabVIEW 2012(32 bit) with the 2012 run-time, but it will not be possible to load a 2012 built one in 2009 with the 2009 run-time if you have used features that are unavailable. This just pushes the maintenance overhead downstream to the installer. Similarly, a dynamic library built in 2009 can be loaded in the IDE of, say, 2012. If you do this,however, you need to test, test, and test some more.

Phew. Many thanks for clarifying.

Bitman

Off topic (apologies). Is 2012 a load point? Or just that you loaded it finally in 2012? More generally. At what version is it planned that 2009 vis will not be loadable?

For everyone? Including Linux, Mac, Pharlap and VxWorks? If you are going to support all the platforms that labview supports, then you will need 6 dynamic libraries and you can't use labVIEW to create some of them. Two is just for windows. However. If you are committed to making the labVIEW driver dependent on a dynamic library (which is the case if you plan to replace it later with a native C implementation) then you are unavoidably making a rod for your own back. Avoid dynamic libraries in LabVIEW if you can - here be monsters (at least you didn't say you wanted .NET or ActiveX ... ).

Well. You don't have to. But if you don't, then those with LabVIEW64 bit won't be able to use it (that's assuming you are only supporting windows ). You are much better off leaving the LabVIEW code for LabVIEW users (and then it will work on all platforms including Linux, Mac etc) and just compile a 32 bit DLL for non-LabVIEW people and worry about the 64 bit when someone (non-labview) asks/pays for it.

And make sure they supply you with the 32 bit & 64 bit versions. Most suppliers think that only the 32 bit is sufficient since 32 bit software can be used in windows. However. LabVIEW 64 bit cannot load 32 bit libraries!

Make sure you specify to whoever is writing it that it must be "Thread-safe". Otherwise you will have to run it in the UI thread. That probably limits it to just you then

No, well. not really. It depends if you are going to have nulls in your data then you could use the C String and not worry about it. However. I'm guessing that because you are looking at string length bytes (pascal style strings can be no more than 256 bytes by-the-way) that you are intending to pass arbitrary length binary data that just happen to be strings.. . There are two ways of transferring variable length data to/from a library. Memory is allocated by labview and the library populates this memory the data (library needs to know the size and the resultant data must be no more than that passed - create and pass array like the ol' for loop of bytes) Memory is allocated by the library and labview accesses this memory (Labview needs to know the size and the resultant data can be any size- moveblock ). Either way. One or the other needs to know the size of the allocated memory. The general method is case no.2 since this does not require pre-allocation, is unlikely to crash because the data is too big and only requires one call for allocation and size, You call the function and have the size as one of the returned parameters and a pointer (uintptr_t) as the other Then use Moveblock to get the data (since it will be known at that point by the size parm). You will also need a separate function to release the memory. This also happens to be the fastest CDECL calling convention is the one of choice as the STDCALL is windows specific (you are intending to port this to other platforms.....right?)

Apart from Daklus sound advice. You might also check that you are using the High Performance Ethernet driver. Not so much for bandwidth, but more for CPU usage. Missing pieces of the image (or entire images) is usually due to bandwidth saturation/collisions. Just because a camera is capable of supplying images at a frame-rate and resolution doesn't mean that it can all be squirted over a LAN interface. You generally have to play with the camera settings to get things working nicely. Whilst the "theoretical" maximum of a 1 GbE is 125MB/s, in reality I have never achieved more than about 100MB/s reliably (assuming jumbo frames are enabled) and a 100Mb interface you will be lucky to get 10MB/s (rule of thumb is about 80% of interface speed). If Jumbo frames aren't being used (default is usually 1500) or are not supported by the interface, then this is usually the bandwidth restriction and you will have to go down to lower resolutions and frame-rates as the packet overhead crucifies the performance (note that if you are going through a router or switch, jumbo frames will also have to be turned on for these devices and match the packet size of the LAN interface).

In my case. I'm pretty sure it's my leopard-print lycra underpants with the elephant trunk codpiece.

Indeed.My brain shuts down contemplating Daklu

Like Comic-con (nerds) without the babes in lycra You shouldn't lose sleep over it

I've done it many times, even to the point of a complete scripting language for one client. It works well as long as you don't have to handle state too much and it is sequential. You end up with files of the formCHECK_VOLTS, TCPIP->READ->MEAS:VOLT:DC?, %.2f Volts, 10, -10

Well. You haven't really given much detail since if a parent class is too much hassle. I would guess anything else would be too. However. There are some simple edge-case scenarios where you can make a flexible system that can be extended without writing additional code at all. Consider a DVM that is CMD->Response for all operations. By defining a "translation" file you can convert operations to commands (or a series of commands) and expected results so that you can use a simple parser and just choose the file dependent on device. If a new DVM is used (but the tests are the same) then you just create a new translation file. You can extrapolate this technique for the tests themselves too. However. It all depends on the system, what you need to do and the complexity/flexibilty required. None of that has to do with classes or VIs, however. It's more a design choice to abstract away hw dependencies from the programming environment.