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    <p>The second and third snippet are functionally equivalent. <code>callParent</code> is just a cleaner and simpler way to invoke the parent's function instead of going through the <code>superclass</code> property. </p> <p>The first example is completely different. For one, it does not call the parent's constructor. This is usually bad news. The base class usually has some initialization that needs to get done, and forgetting to call the parent for constructor (and initComponent) is a common source of bugs. </p> <p><code>initConfig</code> is a convenience method which will: </p> <ul> <li>merge your object's initial config with the config that is passed in</li> <li>create getters and setters for all properties in the config</li> <li>apply the config to the object</li> </ul> <p>This is entirely different from invoking the parent constructor. What invoking the parent constructor does is entirely dependent on what it's written to do. Some will use <code>initConfig</code>, some won't, and others will do similar things that initConfig does, but manually.</p> <p>It's not necessary to use <code>initConfig</code>, and it's even dangerous at times. But that's another story altogether (for Ext 4.1, initConfig looks to be hopefully harmless and not contain the same dangerous side effects that it has in 4.0) </p> <h2>Side Note</h2> <p>Just to point out. In the second and third snippet, the constructor is not needed. If your constructor is only calling the parent's constructor, then you can leave your constructor out altogether.</p>
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    1. POIn ExtJS, callParent() versus initConfig versus superclass
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    1. USMatt Greer
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    1. COthanks, matt. very helpful. could you comment on the difference between the constructor and initialize functions? do they apply to all defined classes? how do they differ?
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    2. COok, learning here... i subclassed a proxy and see that i can override constructor, initialize, and initConfig. i overrode initConfig in order to modify the config - is that appropriate? it worked ok. also, still curious the diff between initialize and constructor
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    3. COYou probably shouldn't override initConfig. I'd argue don't use initConfig at all. Sencha doesn't use initConfig ever in any of their stuff. The reason why is initConfig can blow up on you in certain situations. `initialize` on `Proxy` is private. Probably best to leave it alone. For Proxies I'd say the best way to initialize it is by subclassing the constructor.
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