extends

来源： https://stackoverflow.com/questions/57409183/how-to-fix-class-extends-value-undefined-is-not-a-constructor-or-null-nodejs

来源： https://stackoverflow.com/questions/57409183/how-to-fix-class-extends-value-undefined-is-not-a-constructor-or-null-nodejs

问题 I am trying to lazy-load data from the server into a Map. For that reason I would like to add functionality to Map, so that when a key doesn't exist, a call is done to get the value . What I tried is this: class LazyMap extends Map { // use .length for now. When this works, go use xhr operator [](key) => LazyMap.putIfAbsent(key, () => key.length); } LazyMap test = new LazyMap(); main() { print(test.containsKey('hallo')); // false // I prefer to use this terse syntax and not have to use

问题 I have a parent and child class. class a { val name :String = "jo" def extract(){ println(name) } } now i need to do as below. class b extends a { override def extract(){ override var name :String = "dave". //the problem is here and super.extract() name = "jenny" //here super.extract() } } Issues Im facing now. 1) I cannot use var if im to override the value in class a, needs to be immutable to use override. 2) needs to call the super function twice with different variable. 3) Cannot call

问题 I have a parent and child class. class a { val name :String = "jo" def extract(){ println(name) } } now i need to do as below. class b extends a { override def extract(){ override var name :String = "dave". //the problem is here and super.extract() name = "jenny" //here super.extract() } } Issues Im facing now. 1) I cannot use var if im to override the value in class a, needs to be immutable to use override. 2) needs to call the super function twice with different variable. 3) Cannot call

问题 Here is the thing. I have a main class called A. I want this class to extend class B. class A extends B {} But in fact, I want the class B to extend C, D or E on a specific condition: class B extends B1 {} or class B extends B2 {} or class B extends B3 {} So the B class would be a "fake" class, just to check a condition and then extend the right class. In the final, the result would be the same as: class A extends B1 {} or class A extends B2 {} or class A extends B3 {} I know this is possible

问题 I am trying to create view that has functionality described in a view in am extending, but with different class names. What is happening is the ExpTypesView classes are ['nav','nav-pills'] and ['nav','nav-tabs']. How do i set it so they replace the classnames set in NavView? Resume.NavView = Em.View.extend({ tagName: 'ul', classNames: ['nav','nav-tabs'], currentPathDidChange: function(){ Ember.run.next( this, function() { $("ul li:has(>a.active)").addClass('active'); $("ul li:not(:has(>a

问题 I have a question about using a certian drools functionality in drools decision spreadsheet, that would help a lot in reducing the files and making them more readable. I can't add more than two links so please downlad this .zip file that includes: Version1.PNG, Version1.drl, Version2.PNG, Version2.drl, Version3desired.drl http://s000.tinyupload.com/?file_id=89653236807266194978 So here is the sample rule that we are using right now (something similar)Version1.PNG And this when converted to a

问题 I am very very new to java and trying to extend File class to add some more methods and properties to it with below class import java.io.File; public class RecordingFile extends File { private static final long serialVersionUID = -4774703382591639948L; String RecordingNameFormatted; String RecordingDurationFormatted; String RecordingSizeFormatted; String RecordingDateFormatted; String RecordingBitrateFormatted; public RecordingFile(String path) { super(path); File f = new File(path);

问题 Let's say the following type is defined: interface Shape { color: string; } Now, consider the following ways to add additional properties to this type: Extension interface Square extends Shape { sideLength: number; } Intersection type Square = Shape & { sideLength: number; } What is the difference between both approaches? And, for sake of completeness and out of curiosity, are there other ways to yield comparable results? 回答1: Yes there are differences which may or may not be relevant in your