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// -----------------------------------------------------------------------------
// File: invoke.ss
// Description: a function object that invokes a function of another object
// Author: Alexandre Martins <http://opensurge2d.org>
// License: MIT
// -----------------------------------------------------------------------------
//
// Invoke is a function object that invokes a function of another object. This
// is particularly useful when combined with a FunctionEvent (see below).
//
// Arguments:
// - obj: object. The target object.
// - method: string. The name of the function to be invoked.
// - params: array. The parameters to be passed to the function. It may be empty.
//
// Example:
//
// using SurgeEngine.Events.FunctionEvent;
// using SurgeEngine.Web;
// ...
// fn = FunctionEvent("Invoke")
// .withArgument(Web)
// .withArgument("launchURL")
// .withArgument([ "http://opensurge2d.org" ]);
//
// Calling fn() is equivalent to calling Web.launchURL("http://opensurge2d.org").
// The difference is that fn may be passed as a parameter to other functions!
// This technique lets you store a function call in a variable. In addition,
// you can wrap similar function events in an EventList to store multiple calls.
//
// Note that events do not return a value, whereas Invoke returns the returned
// value of the invoked function, or null on error. A wrapper can be created to
// get the returned value of the invoked function.
//
object "Invoke"
{
fun call(obj, method, params)
{
if(obj === null)
Console.print("Invoke: target object is null");
else if(typeof obj != "object")
Console.print("Invoke: " + obj.toString() + " is not an object");
else if(!obj.hasFunction(method))
Console.print("Invoke: " + obj.__name + "." + method + "() doesn't exist");
else if(typeof params != "object" || params.__name != "Array")
Console.print("Invoke: an array of parameters is expected to call " + obj.__name + "." + method + "()");
else if(obj.__arity(method) != params.length)
Console.print("Invoke: " + obj.__name + "." + method + "() expects " + obj.__arity(method) + " parameters, not " + params.length);
else
return obj.__invoke(method, params);
return null;
}
}
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