LabVIEW Idea Exchange

After working with text-based languages recently, I've become more aware of a very painful flaw in the LabVIEW IDE.

First of all, as software engineer, I like to perform experiments. Make a small change, test it. If it doesn't work, then just use Git to roll back the changes. I've been doing this for years, and with LabVIEW it has been fairly painful. Until recently I didn't realize there was a better way.

Why is it painful? Everytime I use Git to check out a different branch or roll things back, I am forced to close LabVIEW or at least close the project so that LabVIEW detects and loads the new code from disk instead of whatever it has in memory. I lived with that for years because I didn't know any better.

Enter text-based programming and IDEs: VSCode, PyCharm, probably any other modern IDE. I try an experiment, it doesn't work. I roll the changes back in Git and guess what? I don't have to open and close anything! The IDE just automatically detects the file has changed and loads the new file!

When is LabVIEW going to get with the times?

Idea Part 1: The menu that appears when right-clicking an input of the Replace Array Subset node should contain Add Input and Remove Input options.

Idea Part 2: The QuickDrop Remove and Rewire tool (Ctrl + Space, Ctrl + Shift + R) should remove unwired inputs of the Replace Array Subset node.

This would be similar to the menus of several other well-loved nodes, such as the Build Array node.

Real-world example

The other day I wrote the following code:

Initially all the inputs of the Replace Array Subset node were wired. Then I realised I had made a mistake, and needed to remove the third-last pair of wires. I deleted the wires. So far so good.

I then selected the node and pressed Ctrl + Space, Ctrl + Shift + R to execute the QuickDrop Remove and Rewire tool, in the hope that it would eliminate the unwired input. It didn't. I then right-clicked the input, hoping to manually select Remove Input. That option didn't exist.

The only option I had was to manually disconnect the last four wires and reconnect them one input above, followed by removing the last input by dragging the bottom edge upwards.

Having to manually disconnect and reconnect wires was a little disconcerting. I wondered: what would have happened if I had made a mistake with say the second input, instead of the third-last input? A lot more manual wiring would have had to be redone.

Notes

• This idea is deeply related to the following idea: Add "Add Element" and "Remove Element" to the Index Array context menu. However, I arrived at it independently during recent real-world work, as described above.

The Wire Multiple Objects Together QuickDrop tool (Ctrl + W) is extremely useful. However, at the moment it has the following limitation.

The other day I found myself writing code like the following.

Naturally I tried using the QuickDrop Ctrl + W tool. However, it produced the result seen below, which is not what I wanted.

The Ctrl + W tool wires each source wire to a compatible (coerceable) destination. In the example above it wires to I32 and DBL destinations indiscriminately.

The desired outcome would be achieved if the tool preferred wiring to destinations that match the source data type exactly, before considering other compatible (coercible) destinations. In the example above, the tool should prefer the DBL destinations. It should wire to the DBL destinations first, before considering I32 destinations.

Notes

• The example above shows 10 wires being wired between the Index Array node and the Replace Array Subset node. The real-world VIs I was programming the other day required wiring multiple pairs of Index Array and Replace Array Subset nodes, some with as many as 30 wires between them. Wiring them manually was a tedious and time-consuming operation.
• This idea is somewhat related to the following idea: Improvement to the QuickDrop Ctrl+W tool: Wire constant to multiple destinations

This is an idea I've been working on for a while. It's time to let others start evaluating it. 🙂

 ^ I included the above for Dmitry Sagatelyan and similar folks who have asked me for these things over the years so they know the mindset to use when evaluating the idea. But it's written up below for LabVIEW users who only know LabVIEW as it stands today (Q3 2024).

Feedback and questions welcome. 

The asterisk (*) that LabVIEW automatically places in the title bar when a file is modified should be placed first not last so that it can be seen when the window is too narrow to display the whole string, e.g. where other programs like Notepad.exe put it when then text truncation is indicated by an ellipsis (...). Some titles can be much longer when they include lvlib and lvclass contexts.

Problem: Many native VIs use the Non-reentrant execution reentrancy setting.

Solution: The vast majority of native VIs should use the Preallocated clone reentrancy setting.

• The native VIs that need to use Non-reentrant or Shared clone are few and far between - they should be identified on a case-by-case basis. Their Context Help and/or Detailed Help should explain why they need to be set to Non-reentrant or Shared clone.

The following is a selection of vi.lib VIs that should use Preallocated clone. This selection is meant to serve as a starting point and is not comprehensive.

Notes:

• This idea is related to: The reentrancy of new VIs should be "Preallocated clone" . They both argue in favour of using the Preallocated clone setting more.
• A significant number of native VIs are already configured to use Preallocated clone, which is great.
• There are curious cases where closely related VIs are set to different reentrancy settings. For example, Color to RGB.vi is rightly using Preallocated clone, while RGB to Color.vi is Non-reentrant. Similarly, Trim Whitespace.vi is rightly Preallocated clone, while Normalize End Of Line.vi - which lives next to it on the String palette - is Non-reentrant.
  • This suggest that the reentrancy setting of some native VIs was chosen haphazardly. This needs to be rectified.
• The fact that so many native VIs are non-reentrant partly defeats LabVIEW's remarkable ability to create parallel code easily. Loops that are supposed to be parallel and independent are in fact dependent on each other when they use multiple instances of these non-reentrant native VIs. When an application uses multiple instances of these native VIs it is as if there are "hidden semaphores" that are added between the various call locations that call these native VIs. This leads to less performant applications (more CPU cycles, longer execution time, larger EXE compiled code size).

A number of people, myself included, have found it necessary to parse ISO-8601 time strings into time values. The ISO standard has a lot of options, so a complete solution is pretty time-consuming. It would be nice if the string parsing functions in LabVIEW included a format specifier that allowed parsing of ISO-8601 time strings directly.

I understand that empty interface boxes should reflect their purpose, but this design decision wastes too much block diagram space. When using interfaces, explicit type casting is often necessary by definition. Unfortunately, this quickly clutters the block diagram.