How do I make it so that when a bullet from the bullet group collides with an enemy from the enemy group, only the two hitting eachother will get affected?
I tried doing (In playstate):
if (FlxG.collide(bullet, enemy)){
bullet.kill();
enemy.kill();
}
But the only thing this succeeded in doing is killing the entire group. How do I only kill the ones affected?
In the Haxeflixel API docs:
collide(?ObjectOrGroup1:FlxBasic, ?ObjectOrGroup2:FlxBasic, ?NotifyCallback:Dynamic‑>Dynamic‑>Void):Bool
so I think you can use something like:
FlxG.collide(
groupBullets,
groupEnemies,
function (bullet:FlxObject, enemy:FlxObject):Void {
enemy.kill();
bullet.kill();
}
);
You want to pass in a notification callback:
https://github.com/HaxeFlixel/flixel/blob/24529ac96d4ad49a5f0c7e64799d0197cee9049e/flixel/FlxG.hx#L395
So something like this is what you want:
FlxG.collide(bulletGroup, enemyGroup, collideBulletEnemy));
function collideBulletEnemy(bullet:FlxObject, enemy:FlxObject):Void
{
bullet.kill();
enemy.kill();
}
Some more explanation:
The collide() function in flixel lets you pass in either an object or a group to either parameter, and tells you if those two things collide. In the case of two objects, you can directly follow that test up with logic operating on those two objects. But if one of the objects is a group, you don't know based on the test alone which things collided, so you need to rely on a callback you supply yourself to get that specific information.
Related
For work I'm learning Go and Terraform. I read in their tutorial how the different contexts are defined but I'm not clear on exactly when these different contexts are called and what triggers them.
From looking at the Hashicups example it looks like when you put this:
resource "hashicups_order" "new" {
items {
coffee {
id = 3
}
quantity = 2
}
items {
coffee {
id = 2
}
quantity = 2
}
}
in your Terraform file that is going to go look at hashicups_order remove the hashicups prefix and look for a resource called order. The order resource provides the following contexts:
func resourceOrder() *schema.Resource {
return &schema.Resource{
CreateContext: resourceOrderCreate,
ReadContext: resourceOrderRead,
UpdateContext: resourceOrderUpdate,
DeleteContext: resourceOrderDelete,
What isn't clear to me is what triggers each context . From that example it seems like since you are increasing the value of quantity it will trigger the update context. If this were the first run and no previous state existed it would trigger create etc.
However it my case the resource is a server and one API resource I want to present to the user is server power control. However you would never "create/destroy" this resource... or would you? You could read the current power state and you could update the power state but, at least intuitively, you wouldn't create or destroy it. I'm having trouble wrapping my head around how this would be modeled in Terraform/Go. I conceptually understand the coffee resource in the example but I'm having trouble making the leap to imagining what that looks like as something like a server power capability or other things without a clear matching to the different CRUD operations.
I need to find a way to generate a random number each time the REST call is executed.
I have the following GET call:
exec(http("Random execution")
.get("/randomApi")
.queryParam("id", getRandomId()))
}
Obviously it doesn't work as the random number is only generated once and I end up with the same
number whenever this call is executed. I cant use the feeder option as my feeder is already huge and is generated by a 3rd party for each test.
.queryParam takes Expressions as its arguments, and since Expression is an alias for a session function, you can just do...
.queryParam("id", session => getRandomId())
You could also define a second feeder that uses a function to generate the values - no need to update your existing feeder or add another csv file. This would be useful if you had more complicated logic for getting / generating an Id
val idFeeder = Iterator.continually(Map("id" -> Random.nextInt(999999)))
//in your scenario...
.feed(idFeeder)
.exec(http("Random execution")
.get("/randomApi")
.queryParam("id", "${id}")
)
In the spirit of having options, another option you have is to store an object in the session that support toString, which generates whatever you need. It's a nifty trick that you can use for all kinds of things.
object RANDOM_ID {
toString() { return RandomId().toString() }
}
...
exec( _.set( "RANDOM_ID", RANDOM_ID ) )
...
.exec(
http("Random execution")
.get("/randomApi")
.queryParam( "id", "${RANDOM_ID}" )
)
You can apply the same principle to generating random names, addresses, telephone numbers, you name it.
So, which is the better solution? The feeder, or the object in session?
Most of the time, it'll be the feeder, because you control when it is updated. The object in session will be different every time, whereas the feeder solution, you control when the value updates, and then you can reference it multiple times before you change it.
But there may be instances where the stored object solution results in easier to read code, provided you are good with the value changing every time it is accessed. So it's good to know that it is an option.
I've got a question regarding outside-aggregate validation.
In our domain partner can place orders that contain certain products (1).
Once order is placed (2) he can mark it as paid (3) in our system.
Once order is marked as paid (4) we assign licences to products in external library service (5).
Once we know licences are assigned (6) we close entire saga.
Here's a small drawing illustrating the process:
At this moment besides commands, command handlers and events there are two domain classes that are involved in entire process:
Order aggregate containing business logic
Order saga coordinating entire process and assigning licences
Now, there is one invariant that is not modelled in this process yet - before we mark order as paid we have to check if user does not already have particular licence assigned. We get this from library service as well.
Where would you put this validation? Command handler? Wrap Order in some domain service? Pass some validator to Order constructor?
class Order
{
public function __construct(OrderValidator $validator)
{
if (!$validator->isValid($this)) {
throw new \DomainException();
}
// else proceed
}
}
class OrderValidator
{
private $libraryServiceClient;
public function isValid(Order $order)
{
// check licence using $libraryServiceClient
}
}
As far as I understood the problem is in step 3 (Mark order as payed). In this step we need a user (let's call it payer) that marks the order as payed. So when creating this payer object (using factory maybe) we need to know if he is allowed to mark an order as payed. In order to get this information a call should be made to the external library.
What I suggest is to have an application service that have ->markOrderAsPayed($orderId, $payerUserId)
This method will make a call to 2 domain services. One for getting the payer and one for marking the order as payed.
$payer = $this->payerService->getPayer($payerUserId);
$this->orderService->payOrder($orderId, $payer);
In the getPayer() function you should make a call to the external library to know how many licences the payer have.
I hope this will be helpful, it is just based on what I understood from the questions and comments.
I am scraping an 90K record database using JSON-RPC and I am trying to put in some basic error checking. I want to start by scraping the database twice using two different settings and adding a prefix to the second scrape. This way I can check to ensure that the two settings are not producing different records (due to dropped updates, etc). I wanted to implement the comparison using a view which compares each document from the first scrape with it's twin produced by the second scrape and then emit the names of records with a difference between them.
However, I cannot quite figure out how to pull in another doc in the view, everything I have read only discusses external docs using the emit() function, which is too late to permit me to compare it. In the example below, the lookup() function would grab the referenced document.
Is this just not possible?
function(doc) {
if(doc._id.slice(0,1)!=='$' && doc._id.slice(0,1)!== "_"){
var otherDoc = lookup('$test" + doc._id);
if(otherDoc){
var keys = doc.value.keys();
var same = true;
keys.forEach(function(key) {
if ((key.slice(0,1) !== '_') && (key.slice(0,1) !=='$') && (key!=='expires')) {
if (!Object.equal(otherDoc[key], doc[key])) {
same = false;
}
}
});
if(!same){
emit(doc._id, 1);
}
}
}
}
Context
You are correct that this is not possible in CouchDB. The whole point of the map function is that it must be idempotent, otherwise you lose all the other nice benefits of a pre-calculated index.
This is why you cannot access external resources in the map function, whether they be other records or the clock. Any time you run a map you must always get the same result if you put the same record into it. Since there are no relationships between records in CouchDB, you cannot promise that this is possible.
Solution
However, you can still achieve your end goal, just be different means. Some possibilities...
Assuming there is some meaningful numeric value in each doc, you could use a view to take the sum of all those values and group them by which import you did ({key: <batch id>, value: <meaningful number>}). Then compare the two numbers in your client or the browser to see if they match.
A brute force approach would be to use a view to pair the docs that should match. Each doc is on a different row, but they're grouped by a common field. Then iterate through the entire index comparing the pairs. This would certainly be the quickest to code and doesn't depend on your application or data.
Implement a validation function to enforce a schema on your data. Just be warned that this will reduce your write throughput since each written record will be piped out of Erlang and into the JS engine. Also, this is only applicable if you're worried about properly formed records instead of their precise content, which might not be the case.
Instead of your different batch jobs creating different docs, have them place them into the same doc. The structure might look like this: { "_id": "something meaningful", "batch_one": { ..data.. }, "batch_two": { ..data.. } } Then your validation function could compare them or you could create a view that indexes all the docs that don't match. All depends on where in your pipeline you want to do the error checking and correction.
Personally I like the last option better, but only if you don't plan to use the database as is in production. Ie., you wouldn't want to carry around all that extra data in each record.
Hope that helps.
Cheers.
I have a cakephp 1.3 application and I have run into a 'data leak' security hole. I am looking for the best solution using cake and not just something that will work. The application is a grade tracking system that lets teachers enter grades and students can retrieve their grades. Everything is working as expected but when I started to audit security I found that the basic CRUD operations have leaks. Meaning that student X can see student Y's grades. Students should only see their own grades. I will limit this questions to the read operation.
Using cake, I have a grade_controller.php file with this view function:
function view($id = null) {
// Extra, not related code removed
$this->set('grade', $this->grade->read(null, $id));
}
And
http://localhost/grade/view/5
Shows the grade for student $id=5. That's great. But if student #5 manipulates the URL and changes it to a 6, person #6's grades are shown. The classic data leak security hole.
I had two thoughts on the best way to resolve this. 1) I can add checks to every CRUD operations called in the controller. Or 2) add code to the model (for example using beforeFind()) to check if person X has access to that data element.
Option #1 seems like it is time consuming and error prone.
Option #2 seem like the best way to go. But, it required calling find() before some operations. The read() example above never executes beforeFind() and there is no beforeRead() callback.
Suggestions?
Instead of having a generic read() in your controller, you should move ALL finds, queries..etc into the respective model.
Then, go through each model and add any type of security checks you need on any finds that need to be restricted. 1) it will be much more DRY coding, and 2) you'll better be able to manage security risks like this since you know where all your queries are held.
For your example, I would create a getGrade($id) method in my Grade model and check the student_id field (or whatever) against your Auth user id CakeSession::read("Auth.User.id");
You could also build some generic method(s) similar to is_owner() to re-use the same logic throughout multiple methods.
If CakePHP supports isAuthorized, here's something you could do:
Create a column, that has the types of users (eg. 'student', 'teacher', ...)
Now, it the type of User is 'student', you can limit their access, to view only their data. An example of isAuthorized is as follows. I am allowing the student to edit only their profile information. You can extend the concept.
if ((($role['User']['role'] & $this->user_type['student']) == $this->user_type['student']) {
if (in_array($this->action, array('view')) == true) {
$id = $this->params->pass[0];
if ($id == $user_id) {
return (true);
}
}
}
}