4/9/2023 0 Comments Nodatime iclock![]() So, let's wrap the Noda's IClock interface in a static provider that is also async thread-safe :ok_hand. that NodaTime prefers the dependency injection method, which as discussed above, I think for a core cross-cutting concern you want to make the usage as easy as possible. Learn how to use NodaTime's Instant and the IClock interface which pretty much does what this is trying to do. Using NodaTimeĪ few weeks after we switched our to using NodaTime, a friend raised issue DateTimeProvider #29 that I should use Noda Time instead. After a bit of research, If you're in a similar situation, I recommend using NodaTime by Jon Skeet - it gives you the much needed confidence that you are capturing date/time correctly. In the application that I'm tech leading, we have non-functional requirements that need precise handling of date and/or time across multiple time-zones. NET Standard Platform Support Matrix for further details. Installation PM > Install-Package NodaTime.NetworkClock This library is targeting. This abstraction works well if your domain only needs DateTime and rough approximations of TimeZone, i.e. A NodaTime.IClock implementation that gets the current time from an NTP server instead of the computer's local clock. This is relatively easier to using AsyncLocal as I'll show you in a bit. One caveat of using a static implementation is that you need to async theadsafe or otherwise this will happen. I think this is a really useful feature as it allows to you to write and test time dependent code.įinally, it has a Rosyln Analyser that detects usages of DateTime.Now and in Visual Studio suggests replacing usages :lightbulb: with DateTimeProvider. It allows you to Pin DateTime so can be manipulated in a fixed scope. I feel like, instead of an interface or class, I want to have a delegate/func definition, but thats possibly just my fascination with functional languages talking. I prefer this approach so that you aren't forced to dependency inject an instance of IClock or IDateTimeProvider down through layers. Side note: Both Java (Clock - also has a timezone property) and NodaTime (IClock) have this, so the precedent is definitely there. Uses static injection that you can access DateTimeProvider.Now from anywhere in your code similar to DateTime.Now. In my (humble) opinion, DateTimeProvider has a few great features: Although its not strictly incorrect to call directly, in the same way as you might call UtcNow, its strongly discouraged as a matter of style for production code. A few years ago, I rolled up my experiences from several projects into a library DateTimeProvider. IClock is intended for use anywhere you need to have access to the current time. I have previously tried to solve the last point using a IClock or ITimeProvider interfaces. Allowing your code to be testable, i.e.Side Note: This is why it's important to always test in a deployed environment before handing over for testing or the Product Owner for sign-off.Forgotting that your API can be hosted in UTC, i.e.Ensuring that you can capture your domain accurately across timezones.The fundamental idea here is a really useful one - but it does get messy to implement.Date and Time is one of those frustrating things in building an application that can be difficult to get right. But be aware of the limitations of that, in terms of other async operations not happening in the meantime. Quoting the NodaTime API reference: IClock is intended for use anywhere you need to have access to the current time. You may have simpler requirements of course - if you don't have anything else going on, you may just be able to advance the clock. You can't just advance the clock and then return a completed task - because you'd want other asynchronous calls to occur in the "simulated time" between starting and completing the delay. ![]() I would say that the test implementation has caused us a lot of problems over time, because it's a really complex thing to simulate. Just like IClock, there's then a singleton implementation which uses Task.Delay - and a test implementation which advances a clock. Task Delay(TimeSpan delay, CancellationToken cancellationToken) In the GAX project I maintain as part of the Google Cloud client libraries, we have this abstraction: public interface IScheduler ![]() What you want is a different abstraction. IClock doesn't have any notion of delaying - it only answers the question of "what's the current time". ![]()
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