I'd like to make wrapper to implement simple data binding pattern -- while some data have been modified all registered handlers are got notified. I have started with this (for js target):
class Main {
public static function main() {
var target = new Some();
var binding = new Bindable(target);
binding.one = 5;
// binding.two = 0.12; // intentionally unset field
binding.three = []; // wrong type
binding.four = 'str'; // no such field in wrapped class
trace(binding.one, binding.two, binding.three, binding.four, binding.five);
// outputs: 5, null, [], str, null
trace(target.one, target.two, target.three);
// outputs: 5, null, []
}
}
class Some {
public var one:Int;
public var two:Float;
public var three:Bool;
public function new() {}
}
abstract Bindable<TClass>(TClass) {
public inline function new(source) { this = source; }
#:op(a.b) public function setField<T>(name:String, value:T) {
Reflect.setField(this, name, value);
// TODO notify handlers
return value;
}
#:op(a.b) public function getField<T>(name:String):T {
return cast Reflect.field(this, name);
}
}
So I have some frustrating issues: interface of wrapped object doesn't expose to wrapper, so there's no auto completion or strict type checking, some necessary attributes can be easily omitted or even misspelled.
Is it possible to fix my solution or should I better move to the macros?
I almost suggested here to open an issue regarding this problem. Because some time ago, there was a #:followWithAbstracts meta available for abstracts, which could be (or maybe was?) used to forward fields and call #:op(a.b) at the same time. But that's not really necessary, Haxe is powerful enough already.
abstract Binding<TClass>(TClass) {
public function new(source:TClass) { this = source; }
#:op(a.b) public function setField<T>(name:String, value:T) {
Reflect.setField(this, name, value);
// TODO notify handlers
trace("set: $name -> $value");
return value;
}
#:op(a.b) public function getField<T>(name:String):T {
trace("get: $name");
return cast Reflect.field(this, name);
}
}
#:forward
#:multiType
abstract Bindable<TClass>(TClass) {
public function new(source:TClass);
#:to function to(t:TClass) return new Binding(t);
}
We use here multiType abstract to forward fields, but resolved type is actually regular abstract. In effect, you have completion working and #:op(a.b) called at the same time.
You need #:forward meta on your abstract. However, this will not make auto-completion working unless you remove #:op(A.B) because it shadows forwarded fields.
EDIT: it seems that shadowing happened first time I added #:forward to your abstract, afterwards auto-completion worked just fine.
Related
I use Prism6 + Unity container for desktop application developing.
This is a long-read, sorry. So I ask at top: Prism SetProperty() function is not rising property changed event if input value is Unity singleton. And I understand why: because input value and save value have same reference to singleton instance. RaisePropertyChanged() don't help in this situation.
Long-read is statring...
So, I have a dependency property in my UserControl component:
public static readonly DependencyProperty WorksheetDataProperty =
DependencyProperty.Register("WorksheetData", typeof(WorksheetDataModel), typeof(SheetUserControl),
new PropertyMetadata(new WorksheetDataModel(), WorksheetDataPropertyChanged));
public WorksheetDataModel WorksheetData {
get { return (WorksheetDataModel)GetValue(WorksheetDataProperty); }
set { SetValue(WorksheetDataProperty, value); }
}
private void WorksheetDataPropertyChanged(WorksheetDataModel worksheetData) {
if (worksheetData == null)
return;
SheetGrid.Model.ActiveGridView.BeginInit();
this.ClearWorksheetModel();
this.ResizeWorksheetModel();
SheetGrid.Model.ActiveGridView.EndInit();
}
private static void WorksheetDataPropertyChanged(
DependencyObject d, DependencyPropertyChangedEventArgs e) {
((SheetUserControl)d).WorksheetDataPropertyChanged((WorksheetDataModel)e.NewValue);
}
It's important for me to invoke actions from WorksheetDataPropertyChanged() function.
And scheme without shared service (singleton) is working well: this function is called.
But now I want to share data between several modules. How I see it: I have some "parent" module, which load\save data from storage and shared this data with several other modules, which can modificate shared data, but can't save it.
And EventAggregator is not convenient for me: I don't want to create copies of data and then collect it again after modifications.
So I register my "shared service" as singleton:
_container.RegisterInstance(new WorksheetDataModel());
Now I can load data from database in "parent" viewmodel to singleton object created in previous step:
var data = _container.Resolve<WorksheetDataModel>();
data.Header = args.Header;
data.User = args.User;
data.RowHeader = new WorksheetRowHeader(_model.ReadRowHeader(data.Header.WshCode));
data.ColHeader = new WorksheetColHeader(_model.ReadColHeader(data.Header.WshCode));
data.Cells = _model.ReadCells(data.Header.WshCode);
Further, I notify child viewmodels about new data in singleton:
data.OnDataChanged?.Invoke();
And now most important code from child viewmodel.
In delegate handler I "apply" new value:
WorksheetData = _container.Resolve<WorksheetDataModel>();
WorksheetData is:
private WorksheetDataModel _worksheetData;
public WorksheetDataModel WorksheetData {
get { return _worksheetData; }
set { SetProperty(ref _worksheetData, value); }
}
And problem in this line:
set { SetProperty(ref _worksheetData, value); }
It works only once at first call, because _worksheetData is null. But then refernce of _worksheetData (pointer) setted to singleton and in all next call value and _worksheetData are identical for SetProperty() and, as result, it just quit.
I tried next code:
set {
SetProperty(ref _worksheetData, value);
RaisePropertyChanged("WorksheetData")
}
But no effect. WorksheetDataPropertyChanged() callback in UserControl component is not calling.
So, I don't know now how to better share some data between several modules.
Thanks for any advice.
WorksheetData does not change, the contents of the WorksheetDataModel instance change.
So to update your bindings,
either WorksheetDataModel implements INotifyPropertyChanged and/or uses INotifyCollectionChanged-implementing collections
or you let the view model listen to WorksheetDataModel.OnDataChanged and raise its own PropertyChanged to update all bindings to WorksheetData.
Example:
private WorksheetDataModel _worksheetData;
public WorksheetDataModel WorksheetData
{
get { return _worksheetData; }
set
{
if (_worksheetData != null)
_worksheetData.OnDataChanged -= DataChangedHandler;
SetProperty(ref _worksheetData, value);
if (_worksheetData != null)
_worksheetData.OnDataChanged += DataChangedHandler;
}
}
private void DataChangedHandler( object sender, DataChangedEventArgs args )
{
RaisePropertyChanged( nameof( WorksheetData ) );
}
I have two table rows at an HTML file. When the first row gets clicked, it changes its styling via classes.add("active_style"). If the second row gets clicked, I would like to clear the first row styling.
I know that I can just write...
querySelector("#first_row_div").classes.clear();
... in order to clear the first row class (and then resetting its style), but in a bigger code I think that observable would be the best fit.
I don't know if observable works for this. But, if it does, how can I do that?
EDIT/UPDATE: I think that the right question is "is there any way to run a function when a variable gets changed?".
Thanks for the help!
You can make a getter/setter for a field and run your function in the setter.
class MyClass {
String _cssClass;
String get cssClass => _cssClass;
set cssClass(String newClass) {
_cssClass = newClass;
updateDom();
}
void updateDom() {
// do important work here
}
}
You can use a model class that extends Observable.
Here you have to call dirtyCheck() to make Observable check for changes and notify listeners.
Dart also offers the ChangeNotifier mixin. Here you don't need to call any method for dirty-checking. When changes are made listeners are invoked.
A simple example I wrote a while ago while examining the functionality
import 'package:observe/observe.dart';
class Notifiable extends Object with ChangeNotifier {
String _input = '';
#reflectable
get input => _input;
#reflectable
set input(val) {
_input = notifyPropertyChange(#input, _input, val + " new");
}
Notifiable() {
this.changes.listen((List<ChangeRecord> record) => record.forEach(print));
}
}
class MyObservable extends Observable {
#observable
String counter = '';
MyObservable() {
this.changes.listen((List<ChangeRecord> record) => record.forEach(print));
}
}
void main() {
var x = new MyObservable();
x.counter = "hallo";
Observable.dirtyCheck();
Notifiable notifiable = new Notifiable();
notifiable.input = 'xxx';
notifiable.input = 'yyy';
}
I am trying to find a way to override a structuremap registry statement containing EnrichWith like so (here is the Registry class):
public class MyRegistry : Registry
{
public MyRegistry()
{
For(typeof(IMyList<int>)).EnrichWith(x => DecorateMyList(x)).Use(typeof(MyListA<int>));
For(typeof(IMyList<int>)).Use(typeof(MyListB<int>));
For<IMyList<string>>().Use<MyListA<string>>();
For<IMyList<string>>().Use<MyListB<string>>();
}
private object DecorateMyList(object o)
{
var genericParameters = o.GetType().GetGenericArguments();
var myListDecoratorType = typeof(MyListDecorator<>).MakeGenericType(genericParameters);
var decorated = Activator.CreateInstance(myListDecoratorType, new []{o});
return decorated;
}
}
public class MyRegistryUser
{
ObjectFactory.GetInstance<IMyList<string>>(); // Good: Returns an instance of MyListB<string> as expected
ObjectFactory.GetInstance<IMyList<int>>(); // Bad: Returns an instance of the decorator containing MyListB<int> - my second rule should have overridden the EnrichWith as well.
}
Am I right to think that there is a glitch in structure map or is there something I'm not seeing?
Thanks in advance
I have code like this:
//Fields
Product _prod, _existingProd;
void Test()
{
_prod = MakeAndPopulateSomeRandomProduct();
_existingProd = GetProdFromDb(1);
Mapper.CreateMap()
.AfterMap((s, d) =>
{
Console.WriteLine(d==_existingProd); //Why does this print false?
//Customize other properties on destination object
});
Mapper.Map(_prod, _existingProd);
}
When I call Test(), false is printed but I expected true. In my scenario, it is important to be able to access the original destination object via the AfterMap argument. I only included the fields to demonstrate the problem but in my real code, I don't have direct access to them. How can I access the object instances passed in to Map() when customizing the mapping?
The following example works. Probably you are using some type converter which creates new instance... Also please provide all mapping configurations to better understand the problem.
[TestFixture]
public class AfterMap_Test
{
//Fields
private Product _prod, _existingProd;
[Test]
public void Test()
{
Mapper.CreateMap<Product, Product>()
.AfterMap((s, d) =>
{
Trace.WriteLine(d == _existingProd); //Why does this print false?
//Customize other properties on destination object
});
_existingProd = new Product {P1 = "Destination"};
_prod = new Product {P1 = "Source"};
Mapper.Map(_prod, _existingProd);
}
}
internal class Product
{
public string P1 { get; set; }
}
The Goal is to have a list of options (that a user can chose through radio buttons) in one place(for eg: a yaml config file). No other place should have this list hard-coded
I've done something similar to create select elements, and I think enums worked just fine. Doing radio buttons should be very similar. I've set it up so that the labels can be defined in the messages file. I'm going to try to excerpt the relevant portions from my larger auto-form-generation code (using FastTags) the best I can. It's a bit heavy for this one case but it makes sense in the larger system.
I use the tag like #{form.selector 'order.status' /}, which looks find the variable named order in the template, sees that status is declared as public Status status, and then goes to find all the values of the Status enum and generate options for them in the select element.
First, I use a FieldContext object which just contains a bunch of info that's used by the other code to determine what to generate along with some utility methods:
public class FieldContext {
public final Map<?,?> args;
public final ExecutableTemplate template;
public final int fromLine;
public Class clazz = null;
public Field field = null;
public Object object = null;
public Object value = null;
private Map<String,String> attrs = new HashMap<String,String>();
private Map<String,Boolean> printed = new HashMap<String,Boolean>();
private List<Option> options;
...
Then I have this in another helper class (its info gets added to the FieldContext):
public List<Option> determineOptions(FieldContext context) {
List<Option> options = new ArrayList<Option>();
if (context.field.getType().isEnum()) {
for (Object option : context.field.getType().getEnumConstants()) {
options.add(new Option(option.toString(), Message.get(option.toString())));
}
}
return options;
}
then the tag declaration is
public static void _selector(Map<?,?> args, Closure body, PrintWriter out, ExecutableTemplate template, int fromLine) {
String field_name = args.get("arg").toString();
TagContext.current().data.put("name", field_name);
SelectHelper helper = HelperFactory.getHelper(SelectHelper.class);
try {
FieldContext context = new FieldContext(field_name, args, template, fromLine);
helper.autoconfigure(context);
TagContext.current().data.put("selected", helper.determineValue(context));
out.print("<div class=\"formutil-field formutil-selector\">");
out.print("<label for=\"" + context.getAttr("id") + "\">");
out.print(helper.findOrCreateLabel(context));
out.print("</label>");
out.print("<select");
context.printAttribute(out, "id", "name");
out.print(">");
if (context.hasOptions()) {
for (Option option : context.getOptions()) {
out.print("<option value=\"" + option.value + "\">" + option.label + "</option>");
}
}
out.print("</select>");
context.printErrorIfPresent(out);
context.printValidationHints(out);
out.println("</div>");
}
...
}