Coroutine-safe xpcall and pcall versions


Coxpcall encapsulates the protected calls with a coroutine based loop, so errors can be dealed without the usual pcall/xpcall issues with coroutines.

Using Coxpcall usually consists in simply loading the module and then replacing Lua pcall, xpcall and coroutine.running by copcall, coxpcall, and running.

Coxpcall is free software and uses the same license as Lua 5.1 and 5.2.


It supports Lua 5.1, 5.2 and 5.3. Lua 5.2 was extended with the Coxpcall functionality and hence coxpcall is no longer required. The 5.2+ compatibility by coxpcall means that it maintains backward compatibility while using the built-in implementation.


You can get Coxpcall using LuaRocks:

luarocks install coxpcall

See also its GitHub page.


Coxpcall module offers three functions that reproduce the behaviour of pcall, xpcall, and coroutine.running:

local coxpcall = require "coxpcall"
coxpcall.xpcall(f, err)
Offers the same functionality as Lua xpcall(f, err), but calls the error handler after the error unwinds the stack, so that it's impossible to gather more information about the error. To compensate, if the error is a string, stack trace is appended to it. Also set as global coxpcall.
coxpcall.pcall(f, ...)
Offers the same functionality as Lua pcall(f, ...). Also set as global copcall.
Because coxpcall and copcall run the function to protect inside a new coroutine, coroutine.running() will return an unexpected coroutine when used inside the protected function. If the coroutine coro was created by the coxpcall module, then running(coro) will return the original coroutine that created it. If coro is not provided, it will default to the currently running coroutine.


Coxpcall was designed and implemented by Roberto Ierusalimschy and André Carregal with the colaboration of Thomas Harning Jr., Ignacio Burgueño, Gary NG and Fábio Mascarenhas as part of the Kepler Project which holds its copyright.

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