Timepiece | Intuitive date handling in Swift | Date Time Utils library

The component I'm working on is a time input for a form. The form is relatively complex and is generated dynamically, with different fields appearing based on data nested inside other data. I'm managing the state of the form with useReducer, which has worked very well so far. Now that I'm trying to implement a time input component, I'd like to have some basic validation, in particular so I don't get junk non-formatted data into my database. My way of thinking about it was that my database wants one thing: a time, formatted per ISO8601. The UI on the other hand could get that date any number of ways, in my case via an "hour" field, a "minute" field, and eventually an am/pm field. Since multiple fields are being individually validated, and then combined into a single ISO string, my approach was to have useState manage the individual fields and their validation, and then dispatch a single processed ISO string to my centralized state.

To get that to work I tried having the onChange listener of the input fields simply update the local state with a validated input, and then have useEffect "listen" to the local state using its dependency array. So each time local state changes, the useEffect callback dispatches an action with the new input, now processed into an ISO string, in its payload. I was a bit surprised this worked, but I still have a lot to learn about.. all of it. Anyways this worked great, or so I thought..

Since the component in question, TimePiece, is being rendered dynamically (inside nested loops) inside of its parent's parent component, when the user changes the form a bit, the TimePiece component gets rendered with new props and state. But therein lies the rub, every time TimePiece is rendered, it has the same state as every other "instance" of TimePiece (it's a function component though). I used some console.logs to find out it's actually maintaining it's separate state until the moment in renders, when it's then set to the state of the last "instance" that was modified.

My central useReducer state is keyed by a series of ids, so it's able to persist as the user changes the view without a similar problem. It's only the local state which isn't behaving properly, and somewhere on the re-render it sends that state to the central useReducer state and overwrites the existing, correct value...

Something is definitely off, but I keep trying different version and just breaking the thing. At one point it was actually fluttering endlessly between the two states... I thought I would consult the internet. Am I doing this completely wrong? Is it some slight tweak? Should I not have dispatch inside of useEffect with a local state dependency?

In particular, is it strange to combine useState and useReducer, either broadly or in the specific way I've done it?

Here is the code.. if it makes no sense at all, I could make a mock version, but so often the problem lies in the specifics so I thought I'd see if anyone has any ideas. Thanks a bunch.

The functions validateHours and validateMinutes shouldn't have much effect on the operation if you want to ignore those (or so I think.....).

"Mark" is the name of the field state as it lives in memory, e.g. the ISO string. io is what I'm calling the user input.

I am looking to calculate the highest precision lat lon for the subsolar point, in a particular datetime moment, as is reasonably possible using pyephem, with the help of some other library(s) if they are needed.

Relevant context: Anyone who has used pyephem, already knows that for certain calculations it requires certain setup values before computing body positions, those values including the datetime (epoch of the observation), the location of the observer, and of course, the body being investigated. Solutions for the subsolar point through the use of pyephem, that I have found online, show the time in utc as the time needed for the pyephem setup.

Remembering way back to my first exposure to astronomy, and to celestial navigation, utc is a variant of a mean day, compared to an actual solar day, where an actual solar day's duration throughout the year varies due to several factors of the nature of the earth's orbit. Because the length of an actual solar day varies throughout the year, for certain types of astronomical calculations, this requires the Equation of Time to more precisely map the actual solar day measurements to a mean and fixed 24 hour day system such as utc. Before the advent of sufficiently accurate 'pendulum movement' clock mechanisms, and now crystal controlled clock mechanisms, going back to when sundials were the accurate timepiece, the more sophisticated sundials included markings to apply a yearly approximation of this important Equation of Time, soon after it had been observed and definitively documented. Therefore, relevant to my question, since utc is a variant of mean day, and not the true solar day, but normalized to 24 hours exactly, there is this question now of how or if pyephem incorporates the Equation of Time in its right ascension solutions for the sun. At present, I imagine the EoT is required for accuracy, as I try to visualize the sun's position against the background of stars, as seen from the earth, as the earth revolves around the sun, with historically observed variations that are made available and useful and essential with the Equation of Time.

Summary then of my question:

If it is not necessary to explicitly enter an EoT value in pyephem, because it is not relevant for computing the most accurate subsolar point, please explain why. If it is relevant, as I presently think it is, please tell me if pyephem, in its right acension calculation of the sun (and other bodies), as a body, does in fact, apply the Equation of Time as appropriate. Does it do so transparently? Is there a way to input an explicit value for it, if such is known, an EoT value that might be more accurate or more up to date compared to what pyephem is using transparently?

Some initial research results that formed the question: Upon doing a search through various search engines, I found several posts in topical forums that give what seems a very simple answer for finding the subsolar point. Finding the lattitude apears to be the less complicated part of the solution, being simply the computed declination. Finding the longitude is where the question arose in my thinking, and now I wonder if it is applicable for the declination as well, since using the properly precise time is essential for the most precise result of both declination(lat) and longitude of the subsolar point. I always applied the EoT from the Nautical Almanac, back when I was involved with celestial navigation.

Two links, specific to pyephem, present the same approach to the subsolar point solution. When the question(s) was first asked, Brandon Rhodes quickly presented the single line formula using pyephem's computing of the sun's right ascension. His was specifically the code for the longitude calculation in a more theoretical tone, without all the pyephem contextual details. Liam Kennedy presented a more complete context of python code, showing those additional pyephem details, so that one could 'copy and paste' the entire block of code, (needing only to add the import ephem and import datetime), and modify it as appropriate, which I also found to be a useful review. The code is from these links...

Computing sub-solar point

Confusion with using dec/ra to compute sub-lunar location

subsolar point:

Brandon's code

When I point the Tomcat and TomEE Integration plugin in IntelliJ Ultimate 2017.2 via menu item Run > Edit Configurations to a fresh download of Tomcat 8.5.16, my Vaadin 8.1 app runs successfully. Good.

But when I optionally point the configuration’s Server > Application Server > Configure button > Tomcat base directory to an empty folder, I get a message:

Cant find directory 'Users/basilbourque/apache-tomcat-base-dev/conf'

➠ Must I create this conf folder?

In contrast to IntelliJ, when I point NetBeans IDE to an empty folder when running Tomcat externally, it automatically populates the empty folder with the entire hierarchy of folders and files needed to run the app.

So, okay, I create a conf folder in my otherwise empty folder. This satisfies the Edit Configurations panel. Next, I run my app by running this configuration.

Notice how Unnamed_ is prepended to my application name (timepiece), I get this message in a floating dark-red box within the IntelliJ IDE window:

Error running 'Tomcat 8.5.16'

Cannot load /Users/basilbourque/Library/Caches/IntelliJIdea2017.2/Unnamed_timepiece/conf/server.xml: /Users/basilbourque/Library/Caches/IntelliJIdea2017.2/tomcat/Unnamed_timepiece/conf/server.xml (No such file or directory) (5 minutes ago)

➠ Must I create a server.xml?

Such a requirement confuses me given that as I said above, NetBeans simply populates the external Tomcat "base" empty folder as needed entirely and automatically.

I am also curious why the message repeats the same path with a colon in the middle, though that is a minor issue.

The Vaadin Framework guide has a page describing how to use Column Renderers in a Vaadin Grid. And this page describes implementing renderers, but all too briefly.

I want to implement a InstantRenderer to complement the partial set of java.time renderers added in Vaadin 8.1. Renderers were added for LocalDate & LocalDateTime but not for Instant, OffsetDateTime, and ZonedDateTime. For my Instant renderer I am currently simply applying the current default time zone (ZoneId) to get a ZonedDateTime on which I call the toString method. More could be done, but this is just to get started.

So my code should be very similar to the provided LocalDateTimeRenderer. I am trying to follow that code as an guide.

In searching the Vaadin source code and reading the doc, it seems I need three pieces of source code:

• InstantRenderer ( similar to LocalDateTimeRenderer )
• InstantRendererConnector ( similar to LocalDateTimeRendererConnector )
• InstantRendererState ( similar to LocalDateTimeRendererState )

I have done this, and it all compiles. But my table fails to render, all I get is a white empty box on the page. No errors appear on the console or logs. If I remove my use of my InstantRenderer, and fall back to letting my Instant objects be rendered by the default of their own toString methods, all is well and the table appears as expected. So I know my custom renderer is at fault.

I am a newbie when it comes to "server-side" vs "client-side" Vaadin.

➠ Is there some kind of packaging I need to perform? Currently I have my three classes in my Vaadin project alongside the MyUI source file.

➠ Am I missing some other piece?

I instantiate my renderer by calling the no-arg constructor:

When running my Vaadin app on Tomcat 8.5 externally from IntelliJ Ultimate 2017.2 on macOS Sierra, I get an error message:

Artifact timepiece-ui:war exploded: Error during artifact deployment. See server log for details.

➠ Where is this ‘server log’?

When I look in apache-tomcat-8.5.20 > logs, the folder is empty. Indeed, I cannot find any trace of my app being deployed within apache-tomcat-8.5.20.

➠ Is there some other place where IntelliJ+Tomcat is placing my app and the server logs?

"Logs" dialog box">

I am trying to allow multiple modals in a single page. The html set-up is: