The article below describes the behavior of the Singleton design pattern as an anti-pattern, where it violates the basic principle of creating a single object. We all are very much aware of Singletons, one of the main Creational Design Patterns. It's a very widely and commonly used Design Pattern. Most of you are aware of the advantages and the problems solved by the pattern, but I am not going to deal with those features in this article.
For example, passing a boxed instance to C code for an arbitrary amount of time, then fetching it back out and 'resurrecting it' by using transmute. It must use a Semaphore style guard lock to ensure that multiple tests do not concurrently run, and then unsafely access some kind of static mutable value.
I thought perhaps this implementation would workbut practically speaking it fails because occasionally race conditions result in a duplicate execution of init:. Note specifically that unlike a normal program where you can be certain that your entry point main is always running in a single task, the test runner in Rust does not offer any kind of single entry point like this.
Other, rust lang singleton, than specifying the maximum number of tasks; given dozens of tests, only a handful need to do this sort of thing, and it's slow and pointless to limit the test task pool to one rust lang singleton for this one case. It looks like a use case for std:: Once guarantees that your init will only be executed once, no matter how many times you call INIT.
How can rust lang singleton make a safe static singleton in Rust? Imagine I have a safe wrapper for this sort of API: I thought perhaps this implementation would workbut practically speaking it fails Good opening line for internet dating occasionally race conditions result in a duplicate execution of init: Shepmaster k 11 Levans 8, 1 27 Usage looks like this from the documentation: Rust lang singleton you want a mutable static, you'll need to use a Mutex: James Gilles 3 If you want mutation, that's the point of the question How do I create a global, mutable singleton?