Using the AMD and module paradigm used by UI5, I want to use separate JS classes in distinct JS files to separate my ajax code from the related controllers.
A foundation class will be concerned with common activity such as generic error handling whilst specific classes extending from this will deal with subject-specific ajax communication only. This will NOT be a custom control so no requirement for render capability, metadata, etc.
I wish to benefit from the sap.ui.define functionality and also want my new class to be good UI5 citizen. For example I want to fire my init when the class is instantiated.
Which sapui5 class or classes should I extend from? I am currently using sap/ui/base/Object but would like to know if there is a better choice based on better performance or better fit to purpose.
I am aware of the documentation on custom controls but this seems to focus only on details of classes that render to screen.
This is the skeleton of my current approach:
sap.ui.define(['sap/ui/base/Object'],
function(BaseObject) {
"use strict";
var AjaxBase = BaseObject.extend("myAjaxBase", {
constructor: function(oControl) {
BaseObject.apply(this);
console.log("AjaxBase.constructor() fires")
}
})
AjaxBase.prototype.init = function() {
console.log("AjaxBase.init() fires")
}
return AjaxBase;
}, true)
You can use sap.ui.define even for objects which do not extend sap.ui.base.Object. So if you do not really need functionality provided by UI5 objects you are not forced to extend them. However, in your case it looks like you want to use event support and in this case it would be useful to at least extend sap.ui.base.EventProvider.
As you want to separate backend calls from your controllers it looks like you are using a JSONModel and have more complex use cases than just reads. In this case you could also extend the JSONModel with support for create, update and delete operations.
Related
I've been refactoring my app to make more components stateless/pure components; i.e., they're just functions. However, I noticed that some components will need to connect with the redux store via mapStateToProps. Which causes me to do something like this:
const someComp = (props) => {
const {
funcFromReduxStore,
} = props;
return (
...
<SomeComponent
func={ funcFromReduxStore(myArgs) }
...
);
};
This will not work because I am executing funcFromReduxStore. An easy solution is to wrap the prop in an arrow function. However, this causes many unnecessary re-renders b/c the function won't be bound.
The question then becomes: How do I bind a function in a stateless component?
Is it still stateless if I make it a class, without a constructor, and create a class instance field as so:
class someComp extends React.Component {
const {
funcFromReduxStore,
} = this.props,
wrapper = (x) => funcFromReduxStore(x) // equivalent way to bind w/ ES8+
render() {
...
<SomeCompnent
func={ wrapper(myArgs) }/>
...
}
}
I don't have a constructor, nor state. I want to keep the comopnent stateless, but I also want to bind the function to avoid unncessary re-renders. I also want to continue to keep it stateless b/c React has stated there will be performance benefits for stateless comopnents. Does this qualify as a workaround?
Short answer, no. Stateless functional components need to be simple functions.
You should take a look at the Recompose library for some really cool helpers that allow you to beef up your SFCs.
If you're trying to prevent unnecessary re-renders, you could look into onlyUpdateForKeys() or pure().
EDIT: So, I've been thinking about this a bit more and found this really great article on React component rendering performance. One of the key points in that article that pertains to your question:
Stateless components are internally wrapped in a class without any optimizations currently applied, according to Dan Abramov.
From a tweet in July 2016
So it appears that I was wrong. "Stateless Functional Components" are classes...for now. The confusing thing is that there have been performance improvements theorized:
In the future, we’ll also be able to make performance optimizations specific to these components by avoiding unnecessary checks and memory allocations.
At this point, I think the answer to your question becomes largely subjective. When you make a class that extends a React Component, any instances of your class get the setStateprototype method. Meaning you have the ability to set state. So does that mean it's stateful even if you're not using state? Thanks to #Jordan for the link to the code. SFCs only get a render method on the prototype when they are wrapped in a class by React.
To your point about wanting to bind functions, there's only two reasons I can think of that you'd want to bind the function:
To give the function access to this (the instance of the component). From your example, it doesn't seem like you need that.
To ensure that the function passed as a prop to a child component always retains the same identity. The wrapper function in your example seems unnecessary. The identity of the function is determined by the parent component (or mapStateToProps, or whatever HOC).
You should also take a look at React's PureComponent which does the same kind of shallow checking that the pure() HOC from recompose does.
I'm looking for a way of condensing some of my AS3 code to avoid almost duplicate commands.
The issue is that I have multiple variables with almost the same name e.g. frenchLanguage, englishLanguage, germanLanguage, spanishLanguage
My Controller class contains public static variables (these are accessed across multiple classes) and I need a way to be able to call a few of these variables dynamically. If the variables are in the class you are calling them from you can do this to access them dynamically:
this["spanish"+"Language"]
In AS3 it's not possible to write something like:
Controller.this["spanish"+"Language"]
Is there any way to achieve this? Although everything is working I want to be able to keep my code as minimal as possible.
It is possible to access public static properties of a class this way (assuming the class name is Controller as in your example:
Controller['propertyName']
I'm not sure how this helps to have "minimal code", but this would be a different topic/question, which might need some more details on what you want to achive.
Having said that, I like the approach DodgerThud suggests in the comments of grouping similar values in a (dynamic) Object or Dictonary and give it a proper name.
Keep in mind, that if the string you pass in as the key to the class or dynamic object is created from (textual) user input you should have some checks for the validity of that data, otherwise your programm might crash or expose other fields to the user.
It would make sense to utilize a Dictionary object for a set of variables inherited: it provides a solid logic and it happens to work...
I do not think this is what you are trying to accomplish. I may be wrong.
Classes in AS3 are always wrapped within a package - this is true whether you have compiled from Flash, Flex, Air, or any other...
Don't let Adobe confuse you. This was only done in AS3 to use Java-Based conventions. Regardless, a loosely typed language is often misunderstood, unfortunately. So:
this["SuperObject"]["SubObject"]["ObjectsMethod"][ObjectsMethodsVariable"](args..);
... is technically reliable because the compiler avoids dot notation but at runtime it will collect a lot of unnecessary data to maintain those types of calls.
If efficiency becomes an issue..
Use:
package packages {
import flash.*.*:
class This implements ISpecialInterface {
// Data Objects and Function Model
// for This Class
}
package packages {
import...
class ISpecialInterface extends IEventDispatcher
I know there are view controllers and action controllers. I think that view helpers can be used from views and action helpers used from actions in controllers.
I need a class that at bootstrap or wherever, it initializes a number of configuration options, arrays for things like convert month numbers to their names and role numbers to their names.
How can this be achieved?
Put them in a model and use it anywhere you like by instantiating it and calling its helper methods. All model files are auto loaded whenever you call them.
Have a model Constants.php:
<?php
class Constants {
public static function convertMonth($month) {
doLogic();
return $something;
}
}
?>
In your controller or view:
Constants::convertMonth(12);
You could build a Resource Plugin and then add it to yout bootstrap class.
The Constants class or Resource approaches both work nicely. However, I recently had to undo/upgrade a Constants class based solution to meet new requirements, so you might want to consider your future plans before going down those paths.
Specifically, if you ever intend to support multiple languages, or even different words for the constants in different contexts, check out Zend_Translate API docs, Zend_Translate example, or this blog post.
I have a circumstance where I have to create a lot of forms for an application, the forms are all located in the same package. They are named like: A11111.java, A11112.java, etc.
When the user clicks in the NavigationPane, I wish to load the form into a TabItem and display the form. The issue is I need to dynamically generate the name of the form by appending the form name to the location, such as String formName = "com.foo.appName.client.forms" + e.getData("formCode"); something like that, where e is the event of the user click.
I have looked at several Reflection methods, but you cannot pass a derived string to them. How best to do this? Several posts mention using generators, but I get lost trying to sort their logic, and none have to do with displaying forms.
Note, I am not passing any variables to the forms, or calling any methods in the form java files, also the forms are created using uibinding.
Thanks in advance
if you're aiming at lazy-loading classes via the class-loader, like you would when using the command design pattern, note that it can't be done within a GWT application, as the frameworks JRE emulation only provides a subset of types and/or methods available in the JRE, so most of the reflection API - like forName() - will not be available.
rather than lazy-loading classes, think in terms of lazy-rendering widgets to the DOM. this can be achieved by instantiating all your form classes on module load, but only render upon tab-switching. place all your render-related functionality inside onRender() callbacks and you're good to go:
public class FormItem extends TabItem {
#Override
protected void onRender(Element parent, int index) {
super.onRender(parent, index);
// render related functionality
}
}
I have inherited a project that has an awkwardly big interface declared (lets call it IDataProvider). There are methods for all aspects of the application bunched up inside the file. Not that it's a huge problem but i'd rather have them split into smaller files with descriptive name. To refactor the interface and break it up in multiple interfaces (let's say IVehicleProvider, IDriverProvider etc...) will require massive code refactoring, because there are a lot of classes that implement the interface. I'm thinking of two other ways of sorting things out: 1) Create multiple files for each individual aspect of the application and make the interface partial or 2) Create multiple interfaces like IVehicleProvider, IDriverProvider and have IDataProvider interface inhertit from them.
Which of the above would you rather do and why? Or if you can think of better way, please tell.
Thanks
This book suggests that interfaces belong, not to the provider, but rather to the client of the interface. That is, that you should define them based on their users rather than the classes that implement them. Applied to your situation, users of IDataProvider each use (probably) only a small subset of the functionality of that big interface. Pick one of those clients. Extract the subset of functionality that it uses into a new interface, and remove that functionality from IDataProvider (but if you want to let IDataProvider extend your new interface to preserve existing behavior, feel free). Repeat until done - and then get rid of IDataProvider.
This is difficult to answer without any tags or information telling us the technology or technologies in which you are working.
Assuming .NET, the initial refactoring should be very minimal.
The classes that implement the original interface already implement it in its entirety.
Once you create the smaller interfaces, you just change:
public class SomeProvider : IAmAHugeInterface { … }
with:
public class SomeProvider : IProvideA, IProvideB, IProvideC, IProvideD { … }
…and your code runs exactly the way it did before, as long as you haven't added or removed any members from what was there to begin with.
From there, you can whittle down the classes on an as-needed or as-encountered basis and remove the extra methods and interfaces from the declaration.
Is it correct that most if not all of the classes which implement this single big interface have lots of methods which either don't do anything or throw exceptions?
If that isn't the case, and you have great big classes with lots of different concerns bundled into it then you will be in for a painful refactoring, but I think handling this refactoring now is the best approach - the alternatives you suggest simply push you into different bad situations, deferring the pain for little gain.
One thing to can do is apply multiple interfaces to a single class (in most languages) so you can just create your new interfaces and replace the single big interface with the multiple smaller ones:
public class BigNastyClass : IBigNastyInterface
{
}
Goes to:
public class BigNastyClass : ISmallerInferface1, ISmallerInterface2 ...
{
}
If you don't have huge classes which implement the entire interface, I would tackle the problem on a class by class basis. For each class which implements this big interface introduce a new specific interface for just that class.
This way you only need to refactor your code base one class at a time.
DriverProvider for example will go from:
public class DriverProvider : IBigNastyInterface
{
}
To:
public class DriverProvider : IDriverProvider
{
}
Now you simply remove all the unused methods that weren't doing anything beyond simply satisfying the big interface, and fix up any methods where DriverProvider's need to be passed in.
I would do the latter. Make the individual, smaller interfaces, and then make the 'big' interface an aggregation of them.
After that, you can refactor the big interface away in the consumers of it as applicable.