How can I get this type of usage out of my C++ compiler? Consider a very simple hierarchical state-machine, where you can specify the states are unique enum types (enum class). Here's some use-case pseudo code:
enum class lev0
{
start,
end
};
enum class lev1
{
start,
end
};
enum class lev2
{
start,
end
};
HSMSimple<lev0, lev1, lev2> hsm_lev0;
const HSMSimple<lev1, lev2>& hsm_lev1 = hsm_lev0.nextLevel;
const HSMSimple<lev2>& hsm_lev2 = hsm_lev1.nextLevel;
switch (hsm_lev0)
{
case lev0::start:
switch (hsm_lev1)
{
case lev1::start:
switch (hsm_lev2)
{
case lev2::start:
break;
case lev2::end:
break;
}
break;
case lev1::end:
break;
}
break;
case lev0::end:
break;
}
...
Ideas? I've tried a class as such:
template<typename arg1, typename ... TArgs>
class HSMSimple
{
public:
operator const arg1&() const { return m_lev1; }
operator arg1() { return m_lev1; }
const HSMSimple<TArgs>& nextLev() const { return m_nextLevel; }
HSMSimple<TArgs> nextLev() { return m_nextLevel; }
protected:
arg1 m_lev1;
HSMSimple<TArgs> m_nextLevel;
};
But the compiler says an instantiation must pack the args at that last line in the class. When I try writing 'HSMSimple< TArgs...> m_nextLevel;' just more chaos ensues. I feel like more trickery is needed, but can't figure out what.
Related
I have something similar to the following code snippets. I am simplifying the code here for attempted brevity.
First, a subclass of QAbstractListModel with the following data() implementation, and Q_INVOKABLE get_thing() method, which returns a pointer to a QObject subclass, QML_thing:
QVariant data(QModelIndex& index, int role) {
const auto& thing = m_data.at(index.row()); // shared pointer to QML_thing
switch(role)
{
case Qt::DisplayRole:
return thing->name(); // this works
case WholeThingRole:
return QVariant::fromValue(QML_thing*>(thing.get());
}
}
QML_thing* getThing(int index) const
{
const thing = m_data.at(index); // shared pointer
return thing.get();
}
Next, I have a Repeater in a QML file that has this code:
Repeater {
id: repeater
model: thingModel
ThingDelegate {
thing: wholeThing // This calls the role, but ends up being null
}
onItemAdded {
item.thing = model.getThing(index) // this works, but 'breaks' the binding
}
}
My question is: why doesn't the thing: binding in QML work, but the thing = version does?
I'm trying to translate a ParameterizedTest from JUnit4 to JUnit5 (sadly I'm not particularly skilled in testing).
In JUnit4 I have the following class:
#RunWith(Parameterized.class)
public class AssertionTestCase {
private final TestInput testInput;
public AssertionTestCase(TestInput testInput) {
this.testInput = testInput;
}
#Parameterized.Parameters
public static Collection<Object[]> data() {
return AssertionTestCaseDataProvider.createDataCase();
}
#Test(timeout = 15 * 60 * 1000L)
public void testDailyAssertion() {
LOG.info("Testing input {}/{}", testInput.getTestCase(), testInput.getTestName());
//assert stuffs
}
}
in the AssertionTestCaseDataProvider class I have a simple method generating a collection of Object[]:
class AssertionTestCaseDataProvider {
static Collection<Object[]> createDataCase() {
final List<TestInput> testInputs = new ArrayList<>();
//create and populate testInputs
return testInputs.stream()
.map(testInput -> new Object[]{testInput})
.collect(Collectors.toList());
}
}
I've been trying to translate it using JUnit5 and obtained this:
class AssertionTestCase {
private final TestInput testInput;
public AssertionTestCase(TestInput testInput) {
this.testInput = testInput;
}
public static Collection<Object[]> data() {
return AssertionTestCaseDataProvider.createDataCase();
}
#ParameterizedTest
#MethodSource("data")
void testDailyAssertion() {
LOG.info("Testing input {}/{}", testInput.getTestCase(), testInput.getTestName());
// assert stuffs
}
}
I did not apply any change to the AssertionTestCaseDataProvider class.
Nevertheless, I'm getting the following error:
No ParameterResolver registered for parameter [com.xxx.xx.xxx.xxx.testinput.TestInput arg0] in constructor [public `com.xxx.xxx.xxx.xxx.xxx.AssertionTestCase(com.xxx.xxx.xxx.xxx.testinput.TestInput)]. org.junit.jupiter.api.extension.ParameterResolutionException: No ParameterResolver registered for parameter [com.xxx.xx.xxx.xxx.testinput.TestInput arg0] in constructor [public com.xxx.xxx.xxx.xxx.xxx.AssertionTestCase(com.xxx.xxx.xxx.xxx.testinput.TestInput)].`
I understand I'm probably not applying correctly JUnit5 when initializing the input collection for the test. Am I missing some annotations?
I've also tried to use #ArgumentSource instead of #MethodSource and implementing Argument for AssertionTestCaseDataProvider, with the same failing results.
It works in a bit another way in Junit5.
Test Method should have parameters, and provider method should return a Stream.
static Stream<Arguments> data(){
return Stream.of(
Arguments.of("a", 1),
Arguments.of("d", 2)
);
}
#ParameterizedTest
#MethodSource("data")
void testDailyAssertion(String a, int b) {
Assertions.assertAll(
() -> Assertions.assertEquals("a", a),
() -> Assertions.assertEquals(1, b)
);
}
In your case you can just return a Stream<TestInput>:
static Stream<TestInput> createDataCase() {
final List<TestInput> testInputs = new ArrayList<>();
//create and populate testInputs
return testInputs.stream();
}
and then in your testMethod:
#ParameterizedTest
#MethodSource("createDataCase")
void testDailyAssertion(TestInput testInput) {
{your assertions}
}
I'm trying to make a use from Steam API data as I like to learn on live examples, and looking at the way various statistics are returned I began to think that OOP approach would suit me best in this case.
What I'm trying to achieve is to loop through all the results, and programatically populate an array with objects of type that corresponds to the actual type of the statistic. I've tried to build myself a basic class, called Statistic, and after instantiating an object determine wheter or not it's class should change (i.e. whether or not to cast an object of type that Statistic is parent to and if so, of what type). How to do that in PHP? My solution gives me no luck, all of the objects are of type Statistic with it's 'type' property being the object I want to store alone in the array. Code:
$data = file_get_contents($url);
$data = json_decode($data);
$data = $data->playerstats;
$data = $data->stats;
$array;
for($i=0;$i<165;$i++)
{
$array[$i] = new Statistic($data[$i]);
echo "<br/>";
}
var_dump($array[10]);
And the classes' code:
<?php
class Statistic
{
public function getProperties()
{
$array["name"] = $this->name;
$array["value"] = $this->value;
$array["type"] = $this->type;
$array["className"] = __CLASS__;
return json_encode($array);
}
public function setType($x)
{
$y = explode("_",$x->name);
if($y[0]=="total")
{
if(!isset($y[2]))
{
$this->type = "General";
}
else
{
if($y[1]=="wins")
{
$this->type = new Map($x);
$this->__deconstruct();
}
if($y[1]=="kills")
{
$this->type = new Weapon($x);
$this->__deconstruct();
}
else $this->type="Other";
}
}
else $this->type = "Other";
}
function __construct($obj)
{
$this->name = $obj->name;
$this->value = $obj->value;
$this->setType($obj);
}
function __deconstruct()
{
echo "deconstructing <br/>";
return $this->type;
}
}
class Weapon extends Statistic
{
public function setType($x)
{
$y = explode("_",$x);
if($y[1]=="kills")
{
$this->type = "kills";
}
else if($y[1]=="shots")
{
$this->type = "shots";
}
else if($y[1]=="hits")
{
$this->type = "hits";
}
}
function __construct($x)
{
$name = explode("_",$x->name);
$this->name = $name[2];
$this->value = $x->value;
$this->setType($x->name);
}
function __deconstruct()
{
}
}
class Map extends Statistic
{
public function setType($x)
{
if($x[1]=="wins")
{
$this->type = "wins";
}
if($x[1]=="rounds")
{
$this->type = "rounds";
}
}
public function setName($name)
{
if(isset($name[3]))
{
if(isset($name[4]))
{
return $name[3] + " " + $name[4];
}
else return $name[3];
}
else return $name[2];
}
function __construct($x)
{
$name = explode("_",$x->name);
$this->name = $this->setName($name);
$this->value = $x->value;
$this->setType($name);
}
function __deconstruct()
{
}
}
Gives the result:
object(Statistic)#223 (3) {
["name"]=> string(18) "total_kills_deagle"
["value"]=> int(33)
["type"]=> object(Weapon)#222 (3) {
["name"]=> string(6) "deagle"
["value"]=> int(33)
["type"]=> string(5) "kills" }
}
Should that determination be driven from the loop itself, the whole advantage of having a set of functions that does everything for me and returns a ready-to-serve data is gone, since I would really have to cast different objects that aren't connected to each other, which is not the case here. How can I achieve returning objects of different type than the object itself is?
For answer your question How can I achieve returning objects of different type than the object itself is?
"Casting to change the object's type is not possible in PHP (without using a nasty extension)"
For more info: Cast the current object ($this) to a descendent class
So you can't change the class type of an instance with type of a derived class. In other world can't change instance of Static with instance of Weapon.
I am actually reading theory about clean code and SOLID principles. I know understand well that we should program to an interface and not to an implementation.
So, I actually try to apply those principles to a little part of my code. I would like to have your advice or point of view so I can know if I am going in the good direction. I'll show you my previous code and my actual so you can visualize the evolution.
To start, i had a method in my controller to check some requirements for every step of an order process (4 steps that the user have to follow in the right order => 1 then 2 then 3 and then 4)
This is my old code :
private function isAuthorizedStep($stepNumber)
{
$isStepAccessAuthorized = TRUE;
switch($stepNumber) {
case self::ORDER_STEP_TWO: // ORDER_STEP_TWO = 2
if (!($_SESSION['actualOrderStep'] >= ORDER_STEP_ONE)) {
$isStepAccessAuthorized = FALSE;
}
break;
case self::ORDER_STEP_THREE:
if (!($_SESSION['actualOrderStep'] >= ORDER_STEP_TWO)) {
$isStepAccessAuthorized = FALSE;
}
break;
...
}
return $isStepAccessAuthorized;
}
public function orderStepTwo()
{
if ($this->isAuthorizedStep(self::ORDER_STEP_TWO) {
return;
}
... // do some stuff
// after all the verifications:
$_SESSION['actualOrderStep'] = ORDER_STEP_TWO
}
Trying to fit to SOLID principles, I splited my code following this logic:
Extracting hard-coded logic from controllers to put it in classes (reusability)
Using Dependency Injection and abstraction
interface RuleInterface {
public function matches($int);
}
class StepAccessControl
{
protected $rules;
public function __construct(array $rules)
{
foreach($rules as $key => $rule) {
$this->addRule($key, $rule);
}
}
public isAccessGranted($actualOrderStep)
{
$isAccessGranted = TRUE;
foreach($this->rules as $rule) {
if (!$rule->matches($actualOrderStep) {
$isAccessGranted = FALSE;
}
}
return $isAccessGranted;
}
public function addRule($key, RuleInterface $rule)
{
$this->rules[$key] = $rule;
}
}
class OrderStepTwoRule implements RuleInterface
{
public function matches($actualStep)
{
$matches = TRUE;
if (!($actualStep >= 1)) {
$isStepAccessAuthorized = FALSE;
}
return $matches;
}
}
class StepAccessControlFactory
{
public function build($stepNumber)
{
if ($stepNumber == 1) {
...
} elseif ($stepNumber == 2) {
$orderStepTwoRule = new OrderStepTwoRule();
return new StepAcessControl($orderStepTwoRule);
}...
}
}
and then in the controller :
public function stepTwoAction()
{
$stepAccessControlFactory = new StepAccessControlFactory();
$stepTwoAccessControl = $stepAccessControlFactory(2);
if (!$stepTwoAccessControl->isAccesGranted($_SESSION['actualOrderStep'])) {
return FALSE;
}
}
I would like to know if I get the spirit and if I am on the good way :)
In C++/CLI code I need to check if the type is a specific generic type. In C# it would be:
public static class type_helper {
public static bool is_dict( Type t ) {
return t.IsGenericType
&& t.GetGenericTypeDefinition() == typeof(IDictionary<,>);
}
}
but in cpp++\cli it does not work the same way, compiler shows the syntax error:
class type_helper {
public:
static bool is_dict( Type^ t ) {
return t->IsGenericType && t->GetGenericTypeDefinition()
== System::Collections::Generic::IDictionary<,>::typeid;
}
};
The best way I find is compare strings like this:
class type_helper {
public:
static bool is_dict( Type^ t ) {
return t->IsGenericType
&& t->GetGenericTypeDefinition()->Name == "IDictionary`2";
}
};
Does anybody know the better way?
PS:
Is it limitation of typeof (typeid) in c++\cli or I do not know "correct" systax?
You could write:
return t->IsGenericType
&& t->GetGenericTypeDefinition() == System::Collections::Generic::IDictionary<int,int>::typeid->GetGenericTypeDefinition();