WoW:API pcall: Difference between revisions

Revision as of 23:03, 25 March 2010

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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, ...);

Arguments

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

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.

@@ Line 1: / Line 1: @@
-<center>'''pcall''' ''-Documentation by [[user:Darjk|Darjk]]-''</center>
+{{luaapi}}
+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, ...);
-Native Lua statement:
+== Arguments ==
+;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 a boolean value to catch errors from the function call (func).
+== Returns ==
+;retOK : Boolean - If the call to the function (that was passed to pcall) succeeded, returns true. If an error occured, returns false.
- retVal = pcall (func, arg1, arg2, ...);
+;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.
-== Parameters ==
-=== Arguments ===
-:(func, arg1, arg2, ...)
-:;func : Function - The function that will be called (from within) pcall().
-:;arg1 : Variable - Any variable that is also to be passed with the function when its called (if any).
-:;arg2 : Variable - Same as arg1.
-=== Returns ===
-;''Returns''
-:retVal
-:;retvaL : Boolean - If the call to the function (that was passed to pcall) succeeded, returns true. If an error occured, returns false.
 == Example ==
-  function myTest()
+  function myTest(incrementVal)
-    local strTest = "I am a string";
+    return incrementVal + 10;
-   strTest = strTest + 10;
   end
-  local retVal = pcall(myTest);
+  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 return false.
+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.
- retVal = false;
 ==Details==
 : pcall will ''also'' return other arguments returned from the "function" if all is successful.
-{{LUA}}

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