CODEWITHSUNDEEP
actionscript-3propertiesoperators
Maltram
Maltram

Reputation: 49

AS3: calling a property by name or by reference

I am kinda new to AS and stumbled upon a "funny looking" feature in the documentation:

You can use the Object class to create associative arrays. At its core, an associative array is an instance of the Object class, and each key-value pair is represented by a property and its value. Another reason to declare an associative array using the Object data type is that you can then use an object literal to populate your associative array (but only at the time you declare it). The following example creates an associative array using an object literal, accesses items using both the dot operator and the array access operator, and then adds a new key-value pair by creating a new property:

Copy var myAssocArray:Object = {fname:"John", lname:"Public"};
 trace(myAssocArray.fname);     // John
 trace(myAssocArray["lname"]);  // Public
 myAssocArray.initial = "Q";
 trace(myAssocArray.initial);   // Q

from here.

I understand that there are cases where this can be helpful, like this one but with a backround in mostly typesafe languages like Java and C# I am a little bit confused about which access-operator is common practice and why.

Normally I would go with the dot oporator, as it allows me and the compiler to keep track of all given properties and you are save regarding typos.

The code I am looking at right now uses both, with no recognizable pattern, which is even more confusing.

Any input on this? Is one better than the other? Why? When to use which one?

Upvotes: 0

Views: 140

Answers (1)

TreeTree
TreeTree

Reputation: 3230

Normally I would go with the dot oporator, as it allows me and the compiler to keep track of all given properties and you are save regarding typos.

You are not safe against typos. When you create an Object, any property that you haven't defined/assigned to will just return undefined.

var awd:Object = {}
awd.aaa++   //NaN
awd ['aaa']++   //NaN

The compiler will not catch any attempt to reference a property that hasn't been defined.

I use the [] method almost exclusively because it does everything I would need the . method to do plus more. The biggest advantage for me is that I can access properties via variables.

var awd:Object = {}
var key:String = 'some_key';
awd [key] = 1;
awd.key = 5;  //This will literally assign to the 'key' property, not what I want

Upvotes: 1

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