drjdpowell

The close function won’t cause a leak if passed a previously closed or invalid reference. However, if the problem is not that the reference was closed, but instead you lost the correct open reference due to a bug in the code upstream, then that still-open reference could be a leak. So make sure the reference actually was properly cleaned up somewhere else.

Oh no, definitely not that. I mean what if the User requests: — the string “Hello” as a DBL? Is this NaN, zero, or an error? What about as an Int32? A timestamp? — for that matter, what about a boolean? Should anything other than ‘true’/‘false' be an error? Any non-‘null'/non-‘false' be true (including the JSON strings “null” and false”)? Or any non ‘true' be false (even the JSON string “true”)? — “1.2Hello” as a DBL? Is this 1.2 or an error? — or just “1.2”, a JSON string, not a JSON numeric? Should we (as we are doing) allow this to be converted to 1.2? — a JSON Object as an Array of DBL? A “Not an array” error, or an array of all the Objects items converted to DBL? — a JSON Scalar as an Array of DBL? Error or a single element array? — a JSON Object as a DBL? Could return the first item, but Objects are unordered, so “first” is a bit problematic. And what if the User asks for an item by name from: — an Object that doesn’t have that named item? Currently this is no error, but we have a “found” boolean output that is false. — an Array or Scalar? Could be an Error, or just return false for “found”. Then for the JSON to Variant function there is: — cluster item name not present in the JSON Object: an error or return the default value Personally, I think we should give as much “loose-typing” as possible, but I’m not sure where the line should be drawn for returning errors.

I’m talking about errors in the conversion from our “JSON” object into LabVIEW datatypes. There are also errors in the initial interpretation of the JSON string (missing quotes, or whatever); there we will definitely need the throw errors, with meaningful information about where the parsing error occurred in the input JSON string. For debugging type conversion problems, one can use the custom probes to look at the sub-JSON objects fed into the “Get as…”; this will be a subset of the full initial JSON string. BTW, heres the previous example where I’ve introduced an error into the Timestamp format (and probed the value just before the “Get”):

Actually, another possible error choice is to basically never throw an error on “Get”; just return a “null” (or zero, NaN, empty string, etc.) if there is no way to convert the input JSON to a meaningful value of that type (this follows the practice of SQLite, which always provides value regardless of a mismatch between requested and stored data type). Then perhaps all “Get” instances should have a “found” boolean output. Ton, Shaun, what do you think?

Just added some improvements to the bitbucket repo. Below is the new “Example Extract… V2” example using the polymorphic Get function. Note that there is no object type casting now, as the function do the casting themselves (throwing an error if the input type is invalid). I’ve also been working on meaningful error messages. On issue I’d like comment on is getting an item in a JSON object when the object isn’t found. Currently this is not an error, but just makes the “found” output false. I would rather get rid of the “found” output and make it an error instead. — James

I also looked into “public domain” and it seemed problematic. I would be happy to get rid of the requirements on binaries (buried in some readme file that none ever reads). The attribution on source code, read by other developers, seems the only meaningful one, and this also create no burden on customers, since one just leaves the license in the code or documentation.

Hi Ton, This is my first use of Hg or bitbucket. I’ve got a bitbucket account, installed TortoiseHg and successfully downloaded the latest JSON version and created a small “change set” ready for “pushing” up to the repository, but my authorization fails. Do you need to add me to your “team”?

Haven’t use GOOP, but Daklu’s “Slave Loop” is an example of an active object with queues to and from the process. Actor Framework is another example, but Daklu’s design will be simpler to understand. — James

Your deeper problem is one of abstraction; your taking the “wire branches make copies” abstraction too literally. Actually, the compiler will only make copies when necessary. And even if copies are made, it will take a lot of copies to match the low performance of storing data in UI elements (which mostly comes from necessary thread-switching into the UI thread). A DVR is what you should actually have chosen to avoid copies, although the best choice may have been to just let the compiler worry about about it.

I haven’t used this function, but I’ve done similar timing, and I find that both forms of timing ("since last", and “on schedule”) are both needed. There is no reason to prefer one over the other as default, and thus it would be simpler to stick with the current behavior as default, with the new one as an option.

First thing we could use are functions to convert between JSON-format strings and regular LabVIEW Text (escaped characters, encoding, add/remove the quotes). I’m weak on regex.

I’ve added a new version to the CR (sorry Ton, I will need to learn how to use Github). I added a JSON to Variant function. Note that I’m trying to introduce as much loose-typing as possible (very natural when going through a string intermediate), so the below example shows conversion between clusters who have many mismatched types, as well as different orders of elements. It would be nice to think about what type conversion should be allowed without throwing an error. And I’ve started on a low-level set of Get/Set polymathic VIs for managing the conversion from JSON Scalers/Arrays to LabVIEW types (very similar to Shaun’s set but without the access by name array). I’ve reformatted two of Shaun’s VIs to be based of the new lower-level ones. The idea is to restrict the conversion logic (which at some point will have to deal with escaped characters, special logic for null (==NaN), Inf, UTF-8 conversion, allowed Timestamp formats, etc.) to be in only one clearly defined place. At some point, I will redo the Variant stuff to work off of these functions rather than relying on the OpenG String Palette as they do now).

Could NI legal not just mail us a simple form to sign?

Oh, copyright violations. Thought you meant I could be sued for damages due to a very unfortunate manifestation of a bug in Trim Whitespace.

Uh, wait, what? Can I be sued for stuff I post on NI.com? Sounds like an argument to not post anything on NI.com. Ties back to my previous point about the NI.com Terms of Use containing disclaimers to protect NI but not posters; do I need to add a legal disclaimer to every post and uploaded sample VI? And if something is adopted into LabVIEW, it becomes NI’s responsibility, surely? That’s why I like the “1 clause BSD”, dropping the binary requirement. The source code requirement is trivially satisfied by placing the license in the FP or BD or hidden away in the documentation. Edit added later: found this link: The Amazing Disappearing BSD License BTW to OpenG developers (JG if he’s reading): does OpenG not have some transfer of copyright to OpenG itself? It will be impossible to change licensing terms on OpenG once some of the authors die. I’d like to propose dropping the binary clause.

I like Ton’s idea. And not just for NI; having to compile a list of all licenses to make available in an executable is a pain, especially as no one will ever read them. While providing a license in source code is easy if the license is already on the FP, or BD, or documentation of the VI’s themselves. What about a test case? In OpenG there is a Trim Whitespace function that duplicates the same function in LabVIEW. Due to the work of several programmers, OpenG’s version has considerably higher performance. I don’t believe there is any other difference in function, no “advanced” features or anything, and thus no reason why the OpenG version shouldn’t be adopted as standard. What would it take to do this? — James

I could, presumably, post only the core part involving the JSON classes which I wrote, leaving out Shaun’s polymorphic accessors. Or I could get Ton and Shaun’s permission to post the whole thing (maybe; how does that work as only one person can actually post it on NI?).

My reading agrees with yours. Posting to NI.com gives NI an unrestricted license to do whatever they want with it. Further, I don't see why the authors of a work previously released under BSD can't upload it to NI.com and thus grant NI unrestricted use separate from BSD.

My understanding is... that at any moment AQ is going to rightly point out that it is only some lawyer's understanding that actually matters, and there is really no understanding of that. For discussion, what about this unlicense:

On looking carefully at the BSD license the "JSON LabVIEW" is under, and at the "Terms of Use" governing posts on NI.com, I see that both have prominent legal liability disclaimers. BSD says that I'm not liable, while the Terms of Use only says that NI is not liable. Should I be concerned by that? Also, I could not see why I, along with any other copyright holders of "JSON LabVIEW" couldn't legally upload the code to NI.com and thus trigger NI's ability to use the code unhindered by the BSD (I also didn't see anything that indicated that posted code is now owned by NI; just that, by posting, I grant them the right to so whatever they want with it).

Question: As the author of a work released under BSD or some other license, am I not able to re-release it under another, less restrictive license, such as one waiving any attribution requirements? And can I not make it "public domain" with no licensing restrictions at all? Also, as a side point. if I were a company that did not want to allow open-source code, I would certainly not allow arbitrary code posted to ni.com. That such code is legally owned by NI would be immaterial, as it is not tested or certified by NI. Only if such code became part of LabVIEW would it be acceptable. Added later: I should explain that I always assumed that some companies did not allow Open Source software because of concerns about the quality of that code. But if the real issue is attribution and keeping track of all the licenses that have to be reproduced, then that is different. Personally, I don't really care about personal attribution beyond perhaps a note in the code itself. -- James

And I just don't understand them. I picked BSD because it seemed to be to be entirely permissive, except for an acknowledgment. It's not "copy left" which would prevent it from being used in a commercial product. Would making things "public domain" be any better? And though I understand why some companies may shy away from open-source software, preferring all code to come from "approved vendors", how does posting things on NI solve this issue? And for future knowledge, was it posting on the LAVA CR that creates the issue, or was it already tainted once we posted code in a conversation on LAVA? Anyway, this answers a question I've long had: Why does OpenG need a different "Trim Whitespace" VI; why doesn't NI just adopt the higher-performance version as standard LabVIEW? -- James Do you not like VI Package Manger? I think some "JSON" implementations have (perhaps wrongly) allowed these values, so it is probably a good idea to accept things like "Inf", "Infinity", "NaN" when parsing in JSON. When writing JSON, a problem with the 1e5000 idea is that there is no defined size limit for JSON numbers; one could theoretically use it for arbitrarily large numbers. Not that I've ever needed 1e5000 Maybe there should be an input on "Flatten" that selects either strict JSON or allows NaN, Inf and -Inf as valid values. BTW, i'm on vacation without a LabVIEW machine so I'll comment on the excellent code additions when I get back.

Added to the CR. But won’t this package be 3rd party/open source? To everyone but us at least. And OpenG is a “Silver Add-on” on the LabVIEW Tools Network (oooh, shiny!).

View File JSON LabVIEW JSON is a data interchange format (sometimes compared to XML, but simpler). There are multiple projects to create a JSON package for LabVIEW. This is yet another one motivated by this hijacked conversation originally about a different project to convert JSON into LabVIEW Variants. This project uses a set of LVOOP classes to match the recursive structure of JSON, rather than variants. It allows conversation to and from JSON. All functionality is available through two polymorphic VIs: Set and Get. In addition to Get and Set VIs for common data types, one can also convert directly to or from complex clusters via variant-JSON tools. Copyright 2012-2016 James David Powell, Shaun Rumbell, Ton Plomp and James McNally. [Note: if you are using LabVIEW 2017, please also see the JSONtext library as a an alternative.] Submitter drjdpowell Submitted 10/04/2012 Category General LabVIEW Version