Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>This kind of prototype inheritance is often done this way:</p> <pre><code>function Parent() {} function Child() { Parent.call(this); // call the constructor of the parent } var Constr = function() {}; Constr.prototype = Parent.prototype; Child.prototype = new Constr(); Child.prototype.constructor = Child; </code></pre> <p>So the "trick" is to assign the <code>Parent.prototype</code> as prototype to an empty function and set a new instance of this function as prototype of <code>Child</code>.</p> <p>This is done so that extending <code>Child.prototype</code> does not extend <code>Parent.prototype</code>.</p> <p>You also have to call the parent's constructor in the child's constructor. I guess this is the part you struggled with. Every function has a <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/call"><code>call</code> <em><sup>[docs]</sup></em></a> and <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/apply"><code>apply</code> <em><sup>[docs]</sup></em></a> method which let's you explicitly set the element <code>this</code> should refer to inside the function.</p> <p>In your example, it would look like:</p> <pre><code>function Employee(name,title){ this.title=title; Person.call(this, name); } </code></pre> <p>without assigning the constructor to a property of the instance.</p> <p>In your example, <code>this.base(name)</code> works, because through assigning the constructor to a property of the instance (and calling it this way), <code>this</code> inside the function refers to that instance.</p> <hr> <p>There are several libraries implementing this pattern, e.g. <a href="http://closure-library.googlecode.com/svn/docs/closure_goog_base.js.html">Google Closure library</a>:</p> <pre><code>goog.inherits = function(childCtor, parentCtor) { /** @constructor */ function tempCtor() {}; tempCtor.prototype = parentCtor.prototype; childCtor.superClass_ = parentCtor.prototype; childCtor.prototype = new tempCtor(); childCtor.prototype.constructor = childCtor; }; </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POInheritance in JS: this.base = Class(); this.base() or ...?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USFelix Kling
    1. USFelix Kling
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POInheritance in JS: this.base = Class(); this.base() or ...?
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COI cannot express how grateful I am for this answer...
      singulars
      1. PO
      1. USMerc
    2. COI totally understand the function in the Google Closure library (wow, I must be getting somewhere :D ) But! From what I understand, when I create derived class, it's up to me if I want to inherit the internal attributes or not, typing Parent.call(this); or Parent.call(this, name) -- is that right? Wouldn't you ALWAYS want to do that though, really?
      singulars
      1. PO
      1. USMerc
    3. CO@Tony: I think you would. But if you have classical inheritance in mind (like Java), then you also have to call the parent's constructor if you overwrite it. The only difference is that in JavaScript you basically *always* overwrite the constructor because this is how we simulate classes. So it is actually not that different and maybe it is even easier to understand what is going on.
      singulars
      1. PO
      1. USFelix Kling
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload