# on.varChange

This event gets fired when a monitored variable gets changed.
It has an argument it creates by itself (like 'gc' with on.paint), which is varlist, being a list of variable names whose values were changed.
This handler must return a value to indicate if it accepts the new value(s) or vetoes the change.

## Syntax

on.varChange(varlist)

## Return values

Valid return values are:

• 0 Success. The script application accepts the change.
• -1 Veto range. The new value is unsatisfactory because it is outside the acceptable range, i.e. too low or too high.
• -2 Veto type. The new value is unsatisfactory because its type cannot be used by the script application.
• -3 Veto existence. Another application deleted the variable and this application

## Example

This example is about Highscore Saving.
More details here : http://www.inspired-lua.org/index.php/2011/08/save-a-high-score-without-cheating-possibility/

function on.construction()
if not var.recall("highscore") then
highscore = 0
var.store("highscore", highscore)
end
var.monitor("highscore")
end

function on.varChange(varlist)
for k, v in pairs(varlist) do
if k == "highscore" then
if var.recall(k) ~= highscore then
return 1 -- it is an external change, block modifications
else
return 0 -- it is an internal change, allow modifications
end
end
end
return 0 -- allow modifications of other monitored variables if any
end