Module coroutine

Coroutine Manipulation.

The operations related to coroutines comprise a sub-library of the basic library and come inside the table coroutine. See http://www.lua.org/manual/5.1/manual.html#2.11 for a general description of coroutines.

Type coroutine

coroutine.create(f)	Creates a new coroutine, with body f.
coroutine.resume(co, ...)	Starts or continues the execution of coroutine co.
coroutine.running()	Returns the running coroutine, or nil when called by the main thread.
coroutine.status(co)	Returns the status of coroutine co, as a string: "running", if the coroutine is running (that is, it called status); "suspended", if the coroutine is suspended in a call to yield, or if it has not started running yet; "normal" if the coroutine is active but not running (that is, it has resumed another coroutine); and "dead" if the coroutine has finished its body function, or if it has stopped with an error.
coroutine.wrap(f, ...)	Creates a new coroutine, with body f.
coroutine.yield(...)	Suspends the execution of the calling coroutine.

Type coroutine

Field(s)

coroutine.create(f)

Creates a new coroutine, with body f.

f must be a Lua function. Returns this new coroutine, an object with type "thread".

Parameter

• f : a function used as coroutine body.

Return value

#thread: a new coroutine.

coroutine.resume(co, ...)

Starts or continues the execution of coroutine co.

The first time you resume a coroutine, it starts running its body. The values val1, ... are passed as the arguments to the body function. If the coroutine has yielded, resume restarts it; the values val1, ... are passed as the results from the yield.

If the coroutine runs without any errors, resume returns true plus any values passed to yield (if the coroutine yields) or any values returned by the body function (if the coroutine terminates). If there is any error, resume returns false plus the error message.

Parameters

• #thread co : coroutine to start or resume.

• ... : arguments passed to the body function or as result of yield call.

Return values

1. #boolean: true plus any values passed to yield (if the coroutine yields) or any values returned by the body function (if the coroutine terminates)

2. #boolean: false plus an error message.

coroutine.running()

Returns the running coroutine, or nil when called by the main thread.

Return value

#thread: the running coroutine, or nil when called by the main thread.

coroutine.status(co)

Returns the status of coroutine co, as a string: "running", if the coroutine is running (that is, it called status); "suspended", if the coroutine is suspended in a call to yield, or if it has not started running yet; "normal" if the coroutine is active but not running (that is, it has resumed another coroutine); and "dead" if the coroutine has finished its body function, or if it has stopped with an error.

Parameter

• #thread co : a coroutine

Return value

#string: the status : "running", "suspended", "normal" or "dead".

coroutine.wrap(f, ...)

Creates a new coroutine, with body f.

f must be a Lua function. Returns a function that resumes the coroutine each time it is called. Any arguments passed to the function behave as the extra arguments to resume. Returns the same values returned by resume, except the first boolean. In case of error, propagates the error.

Parameters

• f : a function used as coroutine body.

• ... : arguments passed to the body function or as result of yield call.

Return value

Any values passed to yield (if the coroutine yields) or any values returned by the body function (if the coroutine terminates).

coroutine.yield(...)

Suspends the execution of the calling coroutine.

The coroutine cannot be running a C function, a metamethod, or an iterator. Any arguments to yield are passed as extra results to resume.

Parameter

• ... : arguments passed as extra results to resume function.

Return value

Any values passed to the resume function.