when to use initcomponent and when constructor?

[wceuppens]

I had a problem recently while using initcomponent:

Ext.ns("APP.view");
APP.view.North = Ext.extend(Ext.Toolbar, {
    initComponent : function() {
        Ext.apply( this, {
            region    : 'north',
            height    : 30,            // give north region a height
            border    : false,
            margins    : '0 5 0 5',
            items    : this.buildTbar()
        });
        APP.panel.North.superclass.initComponent.call(this);
    },
    .....

using constructor solved the problem:

Ext.ns("APP.view");
APP.view.North = Ext.extend(Ext.Toolbar, {
    constructor : function(config) {
//  config = config || {};
    Ext.applyIf( config, {
        region    : 'north',
        height    : 30,            // give north region a height
        border    : false,
        margins    : '0 5 0 5',
        items    : this.buildTbar()
    });
    APP.view.North.superclass.constructor.call(this, config);
    },
    .....

My question:
Are there situations where it is preferable to use initcompontent? Or is it save to say that constructor is a more safe option in any case?

[Animal]

Because the instances of configs being accessed at construction time, or configs access from initialConfig are not documented, I would say always write your own constructor.

Copy configs into a new object, and fiddle that before calling the superclass constructor.

[Bulle Bas]

I just asked that question on stackoverflow.

I wonder why so many examples and books use initComponent. Does it have advantages over constructor?

Copy configs into a new object, and fiddle that before calling the superclass constructor.

I think wceuppens did that, or do you mean something differently? It is similar to the guidelines in the wiki.

[Animal]

No, wceuppens mutates the config object in his constructor. You have to be careful.

[Animal]

The code must be

config = Ext.apply({
    foo: 'default foo value',
    ...
} config);

You copy config INTO a brand new object, and then pass that NEW OBJECT into the superclass constructor for it to do its business with.

[Bulle Bas]

If the passed config has references itself, you are still not safe, are you? For example

var ref = new Array(1,2,3)
var config = {myRef: ref};

I see no cloning in Ext.apply:

Ext.apply = function(o, c, defaults){
    // no "this" reference for friendly out of scope calls
    if(defaults){
        Ext.apply(o, defaults);
    }
    if(o && c && typeof c == 'object'){
        for(var p in c){
            o[p] = c[p];
        }
    }
    return o;
}; 

Otherwise, we need to update the wiki I think?

[Animal]

Your code creates a new object, and assigns config to reference it. It's fine.

[VinylFox]

Did I miss what the original posters problem was?

I use initComponent over constructor most of the time and can't say I have run into any problems yet.

[Animal]

But you probably set initialConfig properties?

[VinylFox]

I guess I must be if im not running into problems.

Honestly the OP's code seems silly to me, why would you hard code the region of the component your creating, which is where he must have run into trouble since that is set in the constructor. All of the other options he set are trivial.