Summary

Yields execution of thread back to the caller

Prototype

args = coroutine.yield (v1, v2, ...)

Description

Yields execution back to the caller, effectively creating co-operative multi-tasking. Values supplied to yield are returned to coroutine.resume.

The coroutine cannot be running a C function, a metamethod, or an iterator.

Returns any arguments passed to the thread from coroutine.resume.

function f (s)
  print ("Entering f with value", s)
  v = coroutine.yield ("goat")
  print ("After yield, v is", v)
  return 22
end -- f

thread = coroutine.create (f)

ok, result = coroutine.resume (thread, 42) -- start it up
assert (ok, result) -- check ok
print (result) -- see what the yield returned

ok, result = coroutine.resume (thread, 55) -- resume it
assert (ok, result) -- check ok
print (result) -- see what the function returned


 -->
 
Entering f with value 42
goat
After yield, v is 55
22

See Also ...

Lua functions

coroutine.create - Creates a new coroutine thread
coroutine.resume - Start or resume a thread
coroutine.running - Returns the running coroutine
coroutine.status - Returns the status of a thread
coroutine.wrap - Creates a thread and returns a function to resume it

Topics

Lua base functions
Lua bc (big number) functions
Lua bit manipulation functions
Lua coroutine functions
Lua debug functions
Lua io functions
Lua math functions
Lua os functions
Lua package functions
Lua PCRE regular expression functions
Lua script extensions
Lua string functions
Lua syntax
Lua table functions
Lua utilities
Scripting
Scripting callbacks - plugins

(Help topic: lua=coroutine.yield)