anonymous struct and empty struct

by

Note that one interesting aspect of using struct{} for the type pushed to a channel (as opposed to int or bool), is that the size of an empty struct is… 0!

See the recent article “The empty struct” (March 2014) by Dave Cheney.

You can create as many struct{} as you want (struct{}{}) to push them to your channel: your memory won’t be affected.
But you can use it for signaling between go routines, as illustrated in “Curious Channels“.

finish := make(chan struct{})

As the behaviour of the close(finish) relies on signalling the close of the channel, not the value sent or received, declaring finish to be of type chan struct{} says that the channel contains no value; we’re only interested in its closed property.

And you retain all the other advantages linked to a struct:

  • you can define methods on it (that type can be a method receiver)
  • you can implement an interface (with said methods you just define on your empty struct)
  • as a singleton

in Go you can use an empty struct, and store all your data in global variables. There will only be one instance of the type, since all empty structs are interchangeable.

See for instance the global var errServerKeyExchange in the file where the empty struct rsaKeyAgreement is defined.

More Related Contents:

  1. How to broadcast message using channel
  2. Goroutine does not execute if time.Sleep included
  3. How do goroutines work? (or: goroutines and OS threads relation)
  4. No output from goroutine
  5. Is this an idiomatic worker thread pool in Go?
  6. Is it safe to read a function pointer concurrently without a lock?
  7. Can I concurrently write different slice elements
  8. Prevent the main() function from terminating before goroutines finish in Golang
  9. How does select work when multiple channels are involved?
  10. Number of threads used by Go runtime
  11. If I am using channels properly should I need to use mutexes?
  12. Multiple goroutines listening on one channel
  13. How to collect values from N goroutines executed in a specific order?
  14. Closing channel of unknown length
  15. How to recover from concurrent map writes?
  16. What exactly does runtime.Gosched do?
  17. Sudden Increase in the number of goroutines after upgrade [closed]
  18. How to stop a goroutine
  19. cancel a blocking operation in Go
  20. What is the difference between lock, mutex and semaphore?
  21. How does a non initialized channel behave?
  22. What is a coroutine?
  23. Is it OK to leave a channel open?
  24. How safe are Golang maps for concurrent Read/Write operations?
  25. Go http.Get, concurrency, and “Connection reset by peer”
  26. What is channel buffer size?
  27. Go, tcp too many open files debug
  28. How to configure concurrency in .NET Core Web API?
  29. Do buffered channels maintain order?
  30. Are POSIX’ read() and write() system calls atomic?

Leave a Comment