I am using a Cairngorm MVC architecture for my current project.
I have several commands which use the same type of function that returns a value. I would like to have this function in one place, and reuse it, rather than duplicate the code in each command. What is the best way to do this?
Create a static class or static method in one of your Cairngorm classes.
class MyStatic
{
public static function myFunction(value:String):String
{
return "Returning " + value;
}
}
Then where you want to use your function:
import MyStatic;
var str:String = MyStatic.myFunction("test");
Another option is to create a top level function (a la "trace"). Check out this post I wrote here.
You have lots of options here -- publicly defined functions in your model or controller, such as:
var mySharedFunction:Function = function():void
{
trace("foo");
}
... static methods on new or existing classes, etc. Best practice probably depends on what the function needs to do, though. Can you elaborate?
Create an abstract base class for your commands and add your function in the protected scope. If you need to reuse it anywhere else, refactor it into a public static method on a utility class.
Related
I have a quite complex validate method in module1/actions.php called from module1/executeMyAction
I would like to reuse this in module2 rather than duplicate very similar code.
It feels like I should use a component or something like this but I don't need to call validate from a template I need to call it as part of the module1/executeMyAction or module2/executeMyAction so I can then set various variables for the executeMyActionSuccess.php template to handlle.
Can anyone let me know how I should reuse this validation code, I considered moving it into the form class but that just means I can't set the template variiables and it seems like it is breaking the MVC structure a bit so I'm not happy with that.
Would really appreciate any guidance.
If you want to share some parts of code between actions you can create a custom class which will implement some methods you need. You can put the class in the lib directory of either the application or the whole project.
E.g. create a apps/frontend/lib/myUtil.class.php
class myUtil
{
public static function addNumbers($a, $b)
{
return $a + $b;
}
}
Then in your action you can just use:
$sum = myUtil::addNumbers(2, 3);
If your code depends on some other objects it's best if you don't implement static methods but create an object of the class. E.g.
class myUtil
{
protected $request;
public function __construct(sfWebRequest $request)
{
$this->request = $request;
}
public function sumFromRequest()
{
return $this->request->getParameter('a') + $this->request->getParameter('b');
}
}
then in your action
public function executeSomething(sfWebRequest $request)
{
$util = new myUtil($request);
$this->sum = $util->sumFromRequest();
}
If your code is strictly used for validation of form fields you can create a custom validator which can be then used in your form. (which will definitely be the best solution). You can read about creating custom validators in the Symfony docs.
I am loading an swf created in flash professional cs5 via the loader class into a flex 4.1 application. The flash file contains multiple movieclips that are exported for actionscript and those movieclips exist in many instances throughout the movie.
Iterating through everything, comparing class types seems to be the most easy but also the most redundant way to solve this. Is there any way of using the class name as a kind of global selector to access the clips?
I could also make the sub-clips in the flash listen for an event on which they perform an action, but I am not really sure what might be best.
In cases like these, I find that a good way to solve the problem is to create a statically accessable class that manages instances of other classes that are registered with it on instantiation. As an example...
public class GlobalStopper{
private static var clips:Array = [];
public static function add(mc:MovieClip):void{
clips.push(mc);
}
public static function stop():void{
var mc:MovieClip;
for(var i:int = 0, ilen:int = clips.length ; i < ilen ; i++){
mc = clips[i] as MovieClip;
if (mc) mc.stop();
}
}
}
and...
public class GloballyStoppableMovieClip extends MovieClip{
public function GloballyStoppableMovieClip(){
GlobalStopper.add(this);
}
}
Any and all instances of GloballyStoppableMovieClip are instantly registered with the GlobalStopper, so calling
GlobalStopper.stop();
...will stop all registered movieclips.
You can add in any other functions you want. Furthermore, instead of having add accept MovieClip instances, you could have it accept IStoppable or IPlayable objects that implement public functions stop() and play() that your movieclip subclass (or non-movieclip object that also might need to stop and play!) then implements.
But as for jQuery-like selectors? Not really the way I'd handle this particular issue.
i guess typing it out did the trick. i used the event solution:
in the root timeline i placed a function like this:
function cause():void {
dispatchEvent(new Event("do stuff",true));
}
and in the library clip's main timeline goes:
DisplayObject(root).addEventListener("do stuff", function (e:Event=null) {
... whatever ...
});
this is dirty but you get the idea.
Using FluentMigrator, the default creation of a Column using .AsString() results in an nvarchar(255). Is there a simple way (before I modify the FluentMigrator code) to create a column of type nvarchar(MAX)?
You could create an extension method to wrap .AsString(Int32.MaxValue) within .AsMaxString()
e.g.
internal static class MigratorExtensions
{
public static ICreateTableColumnOptionOrWithColumnSyntax AsMaxString(this ICreateTableColumnAsTypeSyntax createTableColumnAsTypeSyntax)
{
return createTableColumnAsTypeSyntax.AsString(int.MaxValue);
}
}
OK, I found it. Basically, use .AsString(Int32.MaxValue). Pity there's not a .AsMaxString() method, but I guess it's easy enough to put in...
You can use AsCustom("nvarchar(max)") and pack it to extension
If you often create columns/tables with the same settings or groups of columns, you should be creating extension methods for your migrations!
For example, nearly every one of my tables has CreatedAt and UpdatedAt DateTime columns, so I whipped up a little extension method so I can say:
Create.Table("Foos").
WithColumn("a").
WithTimestamps();
I think I created the Extension method properly ... I know it works, but FluentMigrator has a LOT of interfaces ... here it is:
public static class MigrationExtensions {
public static ICreateTableWithColumnSyntax WithTimestamps(this ICreateTableWithColumnSyntax root) {
return root.
WithColumn("CreatedAt").AsDateTime().NotNullable().
WithColumn("UpdatedAt").AsDateTime().NotNullable();
}
}
Similarly, nearly every one of my tables has an int primary key called 'Id', so I think I'm going to add Table.CreateWithId("Foos") to always add that Id for me. Not sure ... I actually just started using FluentMigrator today, but you should always be refactoring when possible!
NOTE: If you do make helper/extension methods for your migrations, you should never ever ever change what those methods do. If you do, someone could try running your migrations and things could explode because the helper methods you used to create Migration #1 works differently now than they did earlier.
Here is the code for creating columns incase it helps you create helper methods: https://github.com/schambers/fluentmigrator/blob/master/src/FluentMigrator/Builders/Create/Column/CreateColumnExpressionBuilder.cs
How about extending like this:
public static class StringMaxMigratorExtensions
{
public static ICreateTableColumnOptionOrWithColumnSyntax AsStringMax(this ICreateTableColumnAsTypeSyntax createTableColumnAsTypeSyntax)
{
return createTableColumnAsTypeSyntax.AsCustom("nvarchar(max)");
}
public static IAlterColumnOptionSyntax AsStringMax(this IAlterColumnAsTypeSyntax alterColumnAsTypeSyntax)
{
return alterColumnAsTypeSyntax.AsCustom("nvarchar(max)");
}
}
I have a doubt,.... How would you create a Singleton class in Flex...
Is there any convention like the class name should eb Singleton or it should extend any other class.
How many Singleton class can a project have?
Can anyone say the real time usage of a Singleton class?
I am planning to keep my components label texts in a Singleton class... Is it a good approach.
Can of worms asking about singletons!
There are a few different options about creating singletons mainly due to AS3 not having private constructors. Here's the pattern we use.
package com.foo.bar {
public class Blah {
private static var instance : Blah;
public function Blah( enforcer : SingletonEnforcer ) {}
public static function getInstance() : Blah {
if (!instance) {
instance = new Blah( new SingletonEnforcer() );
}
return instance;
}
...
}
}
class SingletonEnforcer{}
Note that the SingletonEnforcer class is internal so can only be used by the Blah class (effectively). No-one can directly instantiate the class, they have to go through the getInstance() function.
hope I'm not hitting dead horses here :)
(edit: ahh, I'm just repeating phils link)
Gregors singleton implementation does not protect against invoking the constructor with a null value, as in:
var b:Blah = new Blah(null);
You will still have only 1 instance, but invoking the constructor is still possible with the consequences that follows.
If you absolutely must enforce the singleton, the constructor should make sure that the enforcer parameter isn't null.
public function Blah( enforcer : SingletonEnforcer ) {
if(!enforcer){
throw new Error("whoops!");
}
}
You should also be concerned about ApplicationDomain when loading swf files. External swf files that uses the same definitions, may have multiple singleton instances (1 in each separate applicationdomain) if you do not specify that the swf file must be loaded into the existing applicationdomain.
This means that Blah.getInstance() in AAA.swf is not the same instance as Blah.getinstance() in BBB.swf, if AAA.swf loads BBB.swf without a LoaderContext instance that tells the plugin to load BBB.swf into the same ApplicationDomain as AAA.swf
First you can reference a previous question to find out how to create a singleton class. You can find more info from a Yakov Fain presentation as well.
Second question, your project can technology have as may singleton class as you see fit but it will only create 1 instance of each. For example, in the cairngorm architecture you have 3 main singletons: controller, service and model. The number of actual class can very depending on your project.
Finally, A real world solutions would be. You have 2 components that need to talk to each other but you don't want them to know the other exists. Meaning sometimes the components are there and sometimes they are not...so you need them to be loosely coupled. you can uses singletons to pass the data from one component to the other with out "talking" to them directly.
Using singletons is a good approach if you need to pass data around your application from component to component and would like to decouple them from each other.
package com.foo.bar
{
public class MySingleton
{
private static var _instance:MySingleton = new MySingleton;
private var _myName:String;
public static function get instance():MySingleton
{
return _instance;
}
public function set myName(value:String):void
{
_myName = value;
}
public function get myName():String
{
return _myName;
}
}
}
Notice the absence of a constructor here.
Hello you could check out the following of a Flex Singleton Class example on http://www.how-to-code.com/flex/flex-design-patterns/flex-singleton-class.html
Due to requirements outside of my control (don't ask, it's ridiculous) I need to create an AS3 class called 'Math' that references the Global AS Math class. So, for example:
package my.package
{
public class Math
{
public static function pow( a:Number, b:Number ):Number {
// How do I call the Global.as$Math#pow(..) function?
return Math.pow(a,b);
}
}
}
The code above is clearly wrong - results in infinite recursion. I'm not sure how to say that I want to delegate to the Global.as$Math class and not this Math class...
My current awkward solution is to delegate to another class (not named Math) that passes through to the Global Math class. Is there a better way to do this?
Thanks!
Here is another way that popped into my mind after reading Josh Tynjala's post about how package in actionscript are just an abstraction layer over namespaces:
public class Math
{
namespace globalNs = "";
public static function pow( a:Number, b:Number ):Number
{
return globalNs::Math.pow(a, b);
}
}
The globalNs::Math.pow explicitly refer to the top level Math Class.
Save a static reference to the flash player Math object and use it throughout your static methods:
package test
{
import flash.utils.getDefinitionByName;
public class Math
{
private static var _flashMath:Class = Class(getDefinitionByName("Math"));
public static function pow( a:Number, b:Number ):Number
{
return _flashMath.pow(a, b);
}
}
}
Try using the AS3 namespace to refer to the AS3 Math object. Or your class could simply extend the Math object and it would automatically have all of the Math object's functionality without you having to rewrite all those wrapper functions.
As a small follow up on apphackers reply, you can not simple extends the AS3 Math object and have all it's functionality as was suggeested. Static methods are lost when extending an object since they are statically tied to the object which defines them. Additionally you can't extends a class with the same name. You might have some success with the namespace solution however, though I'm not sure if it'll work with static methods, I'd be interested to see your results.
Math is a special case in AS3 because really it shouldn't be global but it is. So it has no namespace as far as I can tell. The solution you came up with to route through another class is actually very clever. But you know that really the solution is to name the class Math2 or MathHelper or MathUtils rather than Math. Please tell me what the reason beyond your control is! The not knowing is killing me!!!