API pcall

From WoWWiki

Calls a function, returning a boolean indicating success as the first return value, and error text / return values as the following values.

retOK, ret1, ret2, ... retn = pcall (func, arg1, arg2, ... argn);

Contents 1 Parameters 1.1 Arguments 1.2 Returns 2 Example 2.1 Result 3 Details

Parameters

Arguments

(func, arg1, arg2, ... argn)

func 

Function - The function that will be called (from within) pcall().

arg1 - argn 

Variable - Any variable that is also to be passed with the function when its called (Optional).

Returns

Returns

retOK, ret1, ret2 ... retn

retOK 

Boolean - If the call to the function (that was passed to pcall) succeeded, returns true. If an error occured, returns false.

ret1 

String (if failed) / Variable - If an error occured, error text is returned; if not, ret1 is the first return value of the original function.

ret2 - retn 

Variable - If the function call succeeded, those return variables contain values returned by original function.

Example

function myTest(incrementVal)
  return incrementVal + 10;
end

local retOK, ret1 = pcall(myTest,"string value");
local msg = "";
if (retOK) then
 msg = "Function succeeded, result: " .. ret1 .. ".";
else
 msg = "Function failed, error text: " .. ret1 .. ".";
end
DEFAULT_CHAT_FRAME:AddMessage(msg);

Result

pcall will catch the error that occured within 'myTest', and output the appropriate text to the default chat window. If "string value" is replaced by a number, the code will output number+10 instead.

Details

pcall will also return other arguments returned from the "function" if all is successful.

 

---

This is a Lua function and documented as part of the World of Warcraft API