Is it possible to get an existing object reference using CEF API?
For example I run a script using ExecuteJavaScript()
function foo()
{
var self = this;
self.value="some value";
}
var fooObj = new foo;
This script creates a new variable fooObj. It is possible to get a reference to this variable later in the C++ code and to modify its value?
You should be able to get it by doing something like the following (untested):
auto context = AppGetBrowser()->GetMainFrame()->GetV8Context();
CefRefPtr<CefV8Value> p = context->GetGlobal()->GetValue(CefString("fooObj"));
You may need to Enter/Exit the context depending on where you're calling it from in C++. Furthermore you may need to actually reference your object explicitly as 'window.fooObj' in which case you'll have to get the value for 'window' and then get 'fooObj' off that.
(edit - accidentally posted too early)
(edit 2 - more)
Related
I am trying to add the instance of an object that I click on to a list on my control object. However when I do so it says that the reference is not set to an instance of an object. The code I have to instantiate the list on the control object is:
public List<Transform> selected = new List<Transform>();
And I tried to add to it to that list using this code attached to the unit:
if (!selected)
{
// Set selected state
selected = true;
// Add to Selected List
control.GetComponent<ForwardCommandScript>().selected.Add(this.transform);
// Set material colour brighter
oldColour = gameObject.renderer.material.color;
newColour = oldColour + new Color(0.2f, 0.2f, 0.2f);
gameObject.renderer.material.color = newColour;
}
I have tried with transform as well. Later I will try to remove it by finding a reference id that was set when the unit is instantiated so should I try to add the script instead of the object if I need to find its variables and then delete the game object attached to the script. I have tried with the GameObject, transform and the class. I wanted to use the class so I can easily access the variables. I have posted this on unity answers and forums but no one replied in the week it was up and I don't like reposting the same stuff on the same site.
Cheers, Scobbo
Your error NullReferenceException: Object reference not set to an instance of an object states that something in the associated line is null. Since the error message doesn't state which part is null, you have to split your code up and check which part is failing.
I'm not sure how you split it up, but try it this way:
var script = control.GetComponent<ForwardCommandScript>();
if (script == null) Debug.Log("script not found");
if (script.selected == null) Debug.Log("selected is null");
script.selected.Add(this.transform);
Now you should get one of the two messages in your debug log before the exception raises. Either the script was not found and you have to check if it is correctly assigned to the game object and if control is the correct game object, or selected is null which should not happen if you initialized it like you posted...
Thanks for adding the complete Error Message :)
you need to replace
control.GetComponent<ForwardCommandScript>().selected.Add(this.transform);
with
control.GetComponent<ForwardCommandScript>().selected.Add(transform);
because
this
is a reference to the script and not the GameObject. you could also use gameObject.transform which transform is just an abbreviation for
I'm using Luabind to bind my Lua scripts to my C++ engine. (it uses lua 5.1.4)
I added a new lua script called "controller.lua" which my entities script, called "cat.lua", will reference and use. One the c++ calls the method "Update" it's all in the hands of Lua.
But once I try to pass my binded c++ methods to the new script file, it feels like all the bindings from that c++ object disapear. I get the following error:
Expression: scripts/controller.lua:5(method MoveUp)
scripts/controller.lua:5: attempt to call method 'GetComponent' (a nil value)
Here is some C++ snippets
// Definitions
module(luaState)
[
class_<Entity>("Entity")
.def("GetComponent", &Entity::GetComponent)
class_<Component>("Component")
.enum_("eComponentTypes")
[
value("Steering", kComponentType_Steering)
],
class_<SteeringComponent>("SteeringComponent")
];
// The script components update
void ScriptComponent::Update() {
const Entity* owner = this.GetOwner();
mLuaDataTable["Update"](owner); // Executes the Update function on the script Cat.lua
}
The entities code being called by c++ (When it executes it returns the Cat table to c++.)
-- Cat.lua
local controller = loadfile("scripts/controller.lua")
local Cat = {}
function Cat.Update(entity)
steeringComponent = entity:GetComponent(Component.Steering) -- Works fine
controller:MoveUp(entity)
end
return Cat
and the Controller
--controller.lua
local up = vec2(0.0, 1.0)
local Controller = {}
function Controller.MoveUp(entity)
steeringComponent = entity:GetComponent(Component.Steering) -- Fails
end
return Controller
Bonus points:
When I make a change to the controller that doesn't work (like if I just threw an s character anywhere), the controller loads up nil, no warnings. Is there some way to make it throw warnings?
Is there a better way I should be doing to "link" to other lua files, like the way im working with Controller?
Thanks to ToxicFrog on Freenode chat for helping me figure this one out.
Basically: I was calling controller MoveUp like so:
controller:MoveUp(entity)
which of course translates into
controller.MoveUp(controller, entity)
and the function was defined as
function Controller.MoveUp(entity)
this "entity" was accepted as the first parameter, controller, while the actual entity is discarded per spec.
http://lua-users.org/wiki/ObjectOrientationTutorial
I need to call a function of an object and pass it a variable. Because I need to make multiple call to function of this object I've tried to make one only handler that invoke the specific function by the form value I pass it. The code works, but CFBuilder show me that there is an error (missing semicolon on the last row). I'm on Railo.
local.myReport = seoUtility.init();
local.func = form.action;
local.report = local.myReport[local.func](form.user);
So the question is: this code is correct? I could simply ignore the cfbuilder error icon?
If you don't want CFBuilder to nag you about the syntax, you can change to this:
local.myReport = seoUtility.init();
local.func = local.myReport[form.action];
local.myReport.func = local.func;
local.report = local.myReport.func(form.user);
This sets local.func to the instance of seoUtility as a reference to the actual function you want to call, preserving its relationship to the parent object. This way the offending []() syntax isn't needed.
However, this only works if seoUtility.init() is returning a fresh instance every time, as opposed to a singleton shared by the application, in which case there would be a race condition on all calls to local.myReport.func().
So I'm working on a little project in which I'm using Python as an embedded scripting engine. So far I've not had much trouble with it using boost.python, but there's something I'd like to do with it if it's possible.
Basically, Python can be used to extend my C++ classes by adding functions and even data values to the class. I'd like to be able to have these persist in the C++ side, so one python function can add data members to a class, and then later the same instance passed to a different function will still have them. The goal here being to write a generic core engine in C++, and let users extend it in Python in any way they need without ever having to touch the C++.
So what I thought would work was that I would store a boost::python::object in the C++ class as a value self, and when calling the python from the C++, I'd send that python object through boost::python::ptr(), so that modifications on the python side would persist back to the C++ class. Unfortunately when I try this, I get the following error:
TypeError: No to_python (by-value) converter found for C++ type: boost::python::api::object
Is there any way of passing an object directly to a python function like that, or any other way I can go about this to achieve my desired result?
Thanks in advance for any help. :)
Got this fantastic solution from the c++sig mailing list.
Implement a std::map<std::string, boost::python::object> in the C++ class, then overload __getattr__() and __setattr__() to read from and write to that std::map. Then just send it to the python with boost::python::ptr() as usual, no need to keep an object around on the C++ side or send one to the python. It works perfectly.
Edit: I also found I had to override the __setattr__() function in a special way as it was breaking things I added with add_property(). Those things worked fine when getting them, since python checks a class's attributes before calling __getattr__(), but there's no such check with __setattr__(). It just calls it directly. So I had to make some changes to turn this into a full solution. Here's the full implementation of the solution:
First create a global variable:
boost::python::object PyMyModule_global;
Create a class as follows (with whatever other information you want to add to it):
class MyClass
{
public:
//Python checks the class attributes before it calls __getattr__ so we don't have to do anything special here.
boost::python::object Py_GetAttr(std::string str)
{
if(dict.find(str) == dict.end())
{
PyErr_SetString(PyExc_AttributeError, JFormat::format("MyClass instance has no attribute '{0}'", str).c_str());
throw boost::python::error_already_set();
}
return dict[str];
}
//However, with __setattr__, python doesn't do anything with the class attributes first, it just calls __setattr__.
//Which means anything that's been defined as a class attribute won't be modified here - including things set with
//add_property(), def_readwrite(), etc.
void Py_SetAttr(std::string str, boost::python::object val)
{
try
{
//First we check to see if the class has an attribute by this name.
boost::python::object obj = PyMyModule_global["MyClass"].attr(str.c_str());
//If so, we call the old cached __setattr__ function.
PyMyModule_global["MyClass"].attr("__setattr_old__")(ptr(this), str, val);
}
catch(boost::python::error_already_set &e)
{
//If it threw an exception, that means that there is no such attribute.
//Put it on the persistent dict.
PyErr_Clear();
dict[str] = val;
}
}
private:
std::map<std::string, boost::python::object> dict;
};
Then define the python module as follows, adding whatever other defs and properties you want:
BOOST_PYTHON_MODULE(MyModule)
{
boost::python::class_<MyClass>("MyClass", boost::python::no_init)
.def("__getattr__", &MyClass::Py_GetAttr)
.def("__setattr_new__", &MyClass::Py_SetAttr);
}
Then initialize python:
void PyInit()
{
//Initialize module
PyImport_AppendInittab( "MyModule", &initMyModule );
//Initialize Python
Py_Initialize();
//Grab __main__ and its globals
boost::python::object main = boost::python::import("__main__");
boost::python::object global = main.attr("__dict__");
//Import the module and grab its globals
boost::python::object PyMyModule = boost::python::import("MyModule");
global["MyModule"] = PyMyModule;
PyMyModule_global = PyMyModule.attr("__dict__");
//Overload MyClass's setattr, so that it will work with already defined attributes while persisting new ones
PyMyModule_global["MyClass"].attr("__setattr_old__") = PyMyModule_global["MyClass"].attr("__setattr__");
PyMyModule_global["MyClass"].attr("__setattr__") = PyMyModule_global["MyClass"].attr("__setattr_new__");
}
Once you've done all of this, you'll be able to persist changes to the instance made in python over to the C++. Anything that's defined in C++ as an attribute will be handled properly, and anything that's not will be appended to dict instead of the class's __dict__.
Now this would seem to be something very straight forward, but seemingly not so in ColdFusion. I need to create an instance of a CFC from within itself as in var a = new this() but this obviously does not work. The CFC name can't be used as it is a base that will be extended so I am attempting a hack around the issue with the following:
component {
public function subQuery (required string table) {
var classPath = getMetaData(this).fullname;
return createObject("component", classPath).init(table, this.dsn);
}
}
This would be acceptable but the class path returned from getMetaData(this).fullname is incorrect. The CFC is within a folder named with a hypen as in my-folder and the returned path looks like my.-folder.myCFC with a period inserted before the hyphen. Obviously I could manipulate this string with a Regex but that is just not a road I want to go down.
Hoping someone has a cleaner approach, thanks.
You should be able to do it without any context on the object name in theory, as it will be being executed from within itself and it should check its current directory.
The following should therefore do the job you need
var classPath = ListLast(getMetaData(this).fullname,'.');
return createObject("component", classPath).init(table, this.dsn);
This way it doesn't matter what the directory names are, and it will work on any objects that extend that one regardless of directory structure, or for a complete example
public function cloneMe() {
return CreateObject('component', ListLast(getMetaData(this).fullname,'.')).init(argumentCollection=arguments);
}
This way any arguments passed in will be passed through into the init. I.e. an extending CFC may redefine the method as the following (if you want errors when the init arguments aren't supplied)
public function cloneMe(required string table) {
return super.cloneMe(table=arguments.table,dsn=this.dsn);
}