I'm trying to learn the correct way inside a Parallel ForEach loop to not reference composition root yet create a thread component based on the component referenced in the composition root.
This is the composition root code:
var builder = new ContainerBuilder();
builder.RegisterType<OperationFiscalCalendarSql>().As<IOperationCloser>().InstancePerDependency();
builder.RegisterType<SQLMessagePoller>().As<IMessagePoller>().SingleInstance();
...
var container = builder.Build();
using (var scope = container.BeginLifetimeScope())
{
...
}
and this is the code that is referenced in the poller object that has the foreach loop:
Parallel.ForEach(messageHeaders, new ParallelOptions { MaxDegreeOfParallelism = _maxDegreeOfParallelism }, messageHeader => {
...
var sapCloser = new OperationFiscalCalendarSql(closeObj, repostiory);
...
});
Note I want an instance of IOperationCloser instead of hardcoding a 'new'ed up OperationFiscalCalendarSql object.
I understand constructor injection I just don't know how to inject an IOperationCloser when it is in any kind of loop.
You can inject a factory in your Poller object with Func<IOperationCloser> and then get a new instance in the ForEach loop.
In your case it may be even better to create your own ILifetimeScope. You can do this by injecting ILieetimeScope in Poller and then call BeginLifetimeScope and Resolve in the loop.
Parallel.ForEach(messageHeaders, ..., m => {
using(ILifetimeScope childScope = scope.BeginLifetimeScope()){
var param1 = new TypedParameter(m);
var closer = childScope.Resolve<IOperationCloser>(param1);
});
});
Related
I build my extbased TYPO3 extension in TYPO3 8.7 . It is a Backend-Module. In the controller, i write my own action to clone the object.
In this example, i want to clone/duplicate the object 'Campaign' and safe it with a modified title, like add the 'copy' text to the title.
But the new object should have also its own new child elements that must be exact copies.
When the action is called, i get only a copy of the Object, but no childs. Is there an example or best case how to handle this task? I did not find, even i found some questions and answers that are on the same topic, but older version. i hope that upd to date, there is a more straight forward solution. Thank you for every hint that points me to the right ideas and maybe an up to date and version example. Here is what i have i my controller. How do i implement recursiv copying of all child elements (and some childs have childs, too)?
/**
* action clone
* #param \ABC\Copytest\Domain\Model\Campaign $campaign
* #return void
* #var \ABC\Copytest\Domain\Model\Campaign $newCampaign
*/
public function cloneAction(\ABC\Copytest\Domain\Model\Campaign $campaign) {
$newCampaign = $this->objectManager->get("ABC\Copytest\Domain\Model\Campaign");
$properties = $campaign->_getProperties();
unset($properties['uid']);
foreach ($properties as $key => $value) {
$newCampaign->_setProperty($key, $value);
}
$newCampaign->_setProperty('title', $properties['title']. ' COPY');
$this->campaignRepository->add($newCampaign);
$this->addFlashMessage('Clone was created', '', \TYPO3\CMS\Core\Messaging\AbstractMessage::OK);
$this->redirect('list');
}
I am aware that this question has been answered a long time ago. But I want to provide my solution to create a deep copy for further reference. Tested on TYPO3 9.5.8.
private function deepcopy($object)
{
$clone = $this->objectManager->get(get_class($object));
$properties = \TYPO3\CMS\Extbase\Reflection\ObjectAccess::getGettableProperties($object);
foreach ($properties as $propertyName => $propertyValue) {
if ($propertyValue instanceof \TYPO3\CMS\Extbase\Persistence\ObjectStorage) {
$v = $this->objectManager->get(\TYPO3\CMS\Extbase\Persistence\ObjectStorage::class);
foreach($propertyValue as $subObject) {
$subClone = $this->deepcopy($subObject);
$v->attach($subClone);
}
} else {
$v = $propertyValue;
}
if ($v !== null) {
\TYPO3\CMS\Extbase\Reflection\ObjectAccess::setProperty($clone, $propertyName, $v);
}
}
return $clone;
}
There is one approach which tackles this usecase from a different POV, namely that request argument values without an identity are automatically put into fresh objects which can then be persisted. This basically clones the original objects. This is what you need to do:
Add a view which has fields for all properties of your object, hidden fields are fine too. This can for example be an edit view with a separate submit button to call your clone action.
Add a initializeCloneAction() and get the raw request arguments via $this->request->getArguments().
Now do unset($arguments[<argumentName>]['__identity']);, do the same for every relation your object has if you want copies instead of shared references.
Store the raw request arguments again via $this->request->setArguments($arguments).
Finally allow the creation of new objects in the property mapping configuration of your argument and possibly all relation properties.
This is how a full initializeCloneAction() could look like:
public function initializeCloneAction()
{
$arguments = $this->request->getArguments();
unset(
$arguments['campaign']['__identity'],
$arguments['campaign']['singleRelation']['__identity'],
);
foreach (array_keys($arguments['campaign']['multiRelation']) as $i) {
unset($arguments['campaign']['multiRelation'][$i]['__identity']);
}
$this->request->setArguments($arguments);
// Allow object creation now that we have new objects
$this->arguments->getArgument('campaign')->getPropertyMappingConfiguration()
->setTypeConverterOption(PersistentObjectConverter::class, PersistentObjectConverter::CONFIGURATION_CREATION_ALLOWED, true)
->allowCreationForSubProperty('singleRelation')
->getConfigurationFor('multiRelation')
->allowCreationForSubProperty('*');
}
Now if you submit your form using the clone action, your clone action will get a fully populated but new object which you can store in your repository as usual. Your cloneAction() will then be very simple:
public function cloneAction(Campaign $campaign)
{
$this->campaignRepository->add($campaign);
$this->addFlashMessage('Campaign was copied successfully!');
$this->redirect('list');
}
If you have "LazyLoadingProxy" instance in your object you need add one more conditions.
if ($propertyValue instanceof \TYPO3\CMS\Extbase\Persistence\Generic\LazyLoadingProxy) {
$objectStorage = $propertyValue->_loadRealInstance();
}
This is my solution for "deepcopy" function:
private function deepcopy($object)
{
$clone = $this->objectManager->get(get_class($object));
$properties = \TYPO3\CMS\Extbase\Reflection\ObjectAccess::getGettableProperties($object);
foreach ($properties as $propertyName => $propertyValue) {
if ($propertyValue instanceof \TYPO3\CMS\Extbase\Persistence\ObjectStorage) {
$objectStorage = $this->objectManager->get(\TYPO3\CMS\Extbase\Persistence\ObjectStorage::class);
foreach ($propertyValue as $subObject) {
$subClone = $this->deepcopy($subObject);
$objectStorage->attach($subClone);
}
} elseif ($propertyValue instanceof \TYPO3\CMS\Extbase\Persistence\Generic\LazyLoadingProxy) {
$objectStorage = $propertyValue->_loadRealInstance();
} else {
$objectStorage = $propertyValue;
}
if ($objectStorage !== null) {
\TYPO3\CMS\Extbase\Reflection\ObjectAccess::setProperty($clone, $propertyName, $objectStorage);
}
}
return $clone;
}
I think a good solution is, to emulate the backend-function.
See the code-example (german text)
http://blog.marcdesign.ch/2015/05/27/typo3-extbase-objekte-kopieren/
The general idea is to extend the TYPO3\CMS\Core\DataHandling\DataHandler and use the parent-method copyRecord. You declare your predefined backend-user to $this->BE_USER in your extend class. The obejct of your predefined backenduser can you get by using the class TYPO3\\CMS\\Backend\\FrontendBackendUserAuthentication and the known name of you predefined backenduser. Your user should have admin-rights and you should define the $BE_USER->uc_default['copyLevels']= '9999'; and declare $BE_USER->uc = $BE_USER->uc_default.
I have not checked, if the declaration $GLOBALS['PAGES_TYPES'][254]['allowedTables'] = '*'; is really needed.
The method copyRecorditself needs mainly the table-name, the uid-value, the pid-value and a language-object as parameters.The languages-object can you get $GLOBALS['lang'], which can although be generated by instanciating \TYPO3\CMS\Lang\LanguageService to $GLOBALS['lang'] and \TYPO3\CMS\Core\Charset\CharsetConverter to $GLOBALS['LANG']->csConvObj.
Sorry about my poor english.
I have data coming from an external source that I want to process. In order to do that, the objects I'm receiving are tagged with their original class name. Now I want to take that tag name and use it to populate a model in my own application. I'm stuck at the step where I check for that class having an equivalent in my codebase. Its going to look something like this:
this.objects.forEach((object) => {
if (typeof object.class_tag !== 'undefined') { //the problem line
//create class instance
}
});
In php I'd simply call class_exists to achieve this
<?php
if (class_exists($object->class_tag)) {}
What is the correct approach here?
I don't see the clear way to do this in a just one line.
One of the possible approaches is the way you register your existing classes.
For example if you use some kind of a namespace later on you can simply check the class for existance in the namespace.
Sample code:
class A {}
const a = "A"
const namespace = { A };
if (namespace[a]) {
// class exists, you can create object
const instance = new namespace[a]();
}
Probably, much better approach would be to make some service, that will registerClass, checkClass and createInstance for you. So your logic is wrapped in one place.
I found a way of doing it
(credit to https://stackoverflow.com/a/34656123/746549)
let logger = require('../javascripts/serverlog');
let util = require('util');
let Extension = require('../models/object/Extension');
const classes = {Extension: Extension};
/**
* Utility to emulate class exists / dynamic class naming
* #param className
* #returns {*}
*/
module.exports.dynamicClass = (className) => {
logger.debug(classes);
logger.debug(className);
if (classes[className]) {
return classes[className];
} else {
return false;
}
};
Usage:
let ClassOrFalse = dynamicClass.dynamicClass(object._class_tag);
for() {
let obj1 = new Object();
}
Is this any different, with regard to performance, from
let obj1;
for() {
obj1 = new Object();
}
Yes. It's different, because when using 'let' that variable will only exists inside the for loop and at every iteration you will be creating a new variable.
When you declare the let obj outside the for, it can be used inside and outside the loop.
Check this for more info https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let
Hope it helped :)
How do we use 'inheritance' in Node.JS? I heard that prototype is similar to interfaces in java. But I have no idea how to use it!
Although there are various ways of performing inheritance and OO in javascript, in Node.js you would typically use the built in util.inherits function to create a constructor which inherits from another.
See http://book.mixu.net/ch6.html for a good discussion on this subject.
for example:
var util = require("util");
var events = require("events");
function MyOwnClass() {
// ... your code.
}
util.inherits(MyOwnClass, events.EventEmitter);
Creating an object constructor in pure JS:
They're just functions like any other JS function but invoked with the new keyword.
function Constructor(){ //constructors are typically capitalized
this.public = function(){ alert(private); }
var private = "Untouchable outside of this func scope.";
}
Constructor.static = function(){ alert('Callable as "Constructor.static()"'); }
var instance = new Constructor();
Inheritance:
function SubConstructor(){
this.anotherMethod(){ alert('nothing special'); }
}
function SubConstructor.prototype = new Constructor();
var instance = new SubConstructor();
instance.public(); //alerts that private string
The key difference is that prototypal inheritance comes from objects, rather than the things that build them.
One disadvantage is that there's no pretty way to write something that makes inheritance of instance vars like private possible.
The whopping gigantor mega-advantage, however, is that we can mess with the prototype without impacting the super constructor, changing a method or property for every object even after they've been built. This is rarely done in practice in higher-level code since it would make for an awfully confusing API but it can be handy for under-the-hood type stuff where you might want to share a changing value across a set of instances without just making it global.
The reason we get this post-instantiated behavior is because JS inheritance actually operates on a lookup process where any method call runs up the chain of instances and their constructor prototype properties until it finds the method called or quits. This can actually get slow if you go absolutely insane with cascading inheritance (which is widely regarded as an anti-pattern anyway).
I don't actually hit prototype specifically for inheritacne a lot myself, instead preferring to build up objects via a more composited approach but it's very handy when you need it and offers a lot of less obvious utility. For instance when you have an object that would be useful to you if only one property were different, but you don't want to touch the original.
var originInstance = {
originValue:'only on origin',
theOneProperty:'that would make this old object useful if it were different'
}
function Pseudoclone(){
this.theOneProperty = "which is now this value";
}
Pseudoclone.prototype = originInstance;
var newInstance = new Psuedoclone();
//accesses originInstance.originValue but its own theOneProperty
There are more modern convenience methods like Object.create but only function constructors give you the option to encapsulate private/instance vars so I tend to favor them since 9 times out of 10 anything not requiring encapsulation will just be an object literal anyway.
Overriding and Call Object Order:
( function Constructor(){
var private = "public referencing private";
this.myMethod = function(){ alert(private); }
} ).prototype = { myMethod:function(){ alert('prototype'); };
var instance = new Constructor();
instance.myMethod = function(){ alert(private); }
instance.myMethod();//"undefined"
Note: the parens around the constructor allow it to be defined and evaluated in one spot so I could treat it like an object on the same line.
myMethod is alerting "undefined" because an externally overwritten method is defined outside of the constructor's closure which is what effective makes internal vars private-like. So you can replace the method but you won't have access to what it did.
Now let's do some commenting.
( function Constructor(){
var private = "public referencing private";
this.myMethod = function(){ alert(private); }
} ).prototype = { myMethod:function(){ alert('prototype'); };
var instance = new Constructor();
//instance.myMethod = function(){ alert(private); }
instance.myMethod();//"public referencing private"
and...
( function Constructor(){
var private = "public referencing private";
//this.myMethod = function(){ alert(private); }
} ).prototype = { myMethod:function(){ alert('prototype'); };
var instance = new Constructor();
//instance.myMethod = function(){ alert(private); }
instance.myMethod();//"prototype"
Note that prototype methods also don't have access to that internal private var for the same reason. It's all about whether something was defined in the constructor itself. Note that params passed to the constructor will also effectively be private instance vars which can be handy for doing things like overriding a set of default options.
Couple More Details
It's actually not necessary to use parens when invoking with new unless you have required parameters but I tend to leave them in out of habit (it works to think of them as functions that fire and then leave an object representing the scope of that firing behind) and figured it would be less alien to a Java dev than new Constructor;
Also, with any constructor that requires params, I like to add default values internally with something like:
var param = param || '';
That way you can pass the constructor into convenience methods like Node's util.inherit without undefined values breaking things for you.
Params are also effectively private persistent instance vars just like any var defined in a constructor.
Oh and object literals (objects defined with { key:'value' }) are probably best thought of as roughly equivalent to this:
var instance = new Object();
instance.key = 'value';
With a little help from Coffeescript, we can achieve it much easier.
For e.g.: to extend a class:
class Animal
constructor: (#name) ->
alive: ->
false
class Parrot extends Animal
constructor: ->
super("Parrot")
dead: ->
not #alive()
Static property:
class Animal
#find: (name) ->
Animal.find("Parrot")
Instance property:
class Animal
price: 5
sell: (customer) ->
animal = new Animal
animal.sell(new Customer)
I just take the sample code Classes in CoffeeScript. You can learn more about CoffeeScript at its official site: http://coffeescript.org/
I have a module Vehicle that contains general vehicle info. I have another module Car, which adds more functionality to Vehicle object.
// Pseudo code only. The final functions do not have to resemble this
var vehicle = require('vehicle')
vehicle.terrain = 'Land'
var car = vehicle.createCar()
// car and anotherCar will have unique Car-related values,
// but will use the same Vehicle info
var anotherCar = vehicle.createCar()
I am looking at using Object.create for the Car module, but not sure where the Object.create calls should go.
Should I have a constructor in the Car module that takes an instance of a Vehicle object and does an Object.create with the Vehicle instance as the prototype?
Or should the Object.create happen in a function on the Vehicle object, like createCar? My issue with this way, is Car should care that it's derived from Vehicle, Vehicle shouldn't know Car requires that.
Or even if Object.create is the right approach.
Please, any examples and best practices would be greatly appreciated.
Update:
I changed the example to better reflect the inheritance problem I'm trying to solve.
imo, you're describing a builder pattern rather than inheritance I think -- I wouldn't use object.create for this. A VehicleBuilder is responsible for constructing an object that has certain properties associated with it.
var builder = new VehicleBuilder();
builder.terrain = 'Land';
builder.wheelCount = 2;
builder.color = "blue";
var motorcycle = builder.createVehicle();
It might use something like:
VehicleBuilder.prototype.createVehicle = function(){
var me = this;
return new Vehicle({
color: me.color,
terrain: me.terrain,
wheelCount: me.wheelCount
});
}
If you look at the typical inheritance pattern in js, its something much more well defined and uses two primary patterns in node. One is util.inherits. Its code is simple: https://github.com/joyent/node/blob/master/lib/util.js#L423-428
exports.inherits = function(ctor, superCtor) {
ctor.super_ = superCtor;
ctor.prototype = Object.create(superCtor.prototype, {
constructor: { value: ctor, enumerable: false }
});
};
And the second is calling the parent constructor in the child class constructor.
function ChildClass(){
SuperClass.call(this); // here
}
Example: https://github.com/joyent/node/blob/master/lib/stream.js#L25-28
So instead of a vehicle taking a bunch of properties or another object in its constructor, you use the prototype chain and the constructor to define custom subclass behavior.
I would recommend a different approach
// foo.js
var topic = require("topic");
topic.name = "History";
topic.emit("message");
topic.on("message", function() { /* ... */ });
// topic.js
var events = require("events");
var Topic = function() {
};
// inherit from eventEmitter
Topic.prototype = new events.EventEmitter();
exports.module = new Topic;
You have a good EventEmitter to do message passing for you. I recommend you just extend the prototype of Topic with it.
Why not just use js native prototype based inheritance? Expose your constructor directly using module.exports:
//vehicle.js
module.exports = function() {
//make this a vehicle somehow
}
Then:
// Pseudo code only. The final functions do not have to resemble this
var Vehicle = require('vehicle')
Vehicle.terrain = 'Land'
var car = new Vehicle()
// car and anotherCar will have unique Car-related values,
// but will use the same Vehicle info
var anotherCar = new Vehicle()