Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>You are referring to the run-time duck-typing as "overriding" inheritance, however I believe inheritance has its own merits as a design and implementation approach, being an integral part of object oriented design. In my humble opinion, the question of whether you can achieve something otherwise is not very relevant, because actually you could code Python without classes, functions and more, but the question is how well-designed, robust and readable your code will be.</p> <p>I can give two examples for where inheritance is the right approach in my opinion, I'm sure there are more. </p> <p>First, if you code wisely, your makeSpeak function may want to validate that its input is indeed an Animal, and not only that "it can speak", in which case the most elegant method would be to use inheritance. Again, you can do it in other ways, but that's the beauty of object oriented design with inheritance - your code will "really" check whether the input is an "animal".</p> <p>Second, and clearly more straightforward, is Encapsulation - another integral part of object oriented design. This becomes relevant when the ancestor has data members and/or non-abstract methods. Take the following silly example, in which the ancestor has a function (speak_twice) that invokes a then-abstract function:</p> <pre><code>class Animal(object): def speak(self): raise NotImplementedError() def speak_twice(self): self.speak() self.speak() class Dog(Animal): def speak(self): print "woff!" class Cat(Animal): def speak(self): print "meow" </code></pre> <p>Assuming <code>"speak_twice"</code> is an important feature, you don't want to code it in both Dog and Cat, and I'm sure you can extrapolate this example. Sure, you could implement a Python stand-alone function that will accept some duck-typed object, check whether it has a speak function and invoke it twice, but that's both non-elegant and misses point number 1 (validate it's an Animal). Even worse, and to strengthen the Encapsulation example, what if a member function in the descendant class wanted to use <code>"speak_twice"</code>?</p> <p>It gets even clearer if the ancestor class has a data member, for example <code>"number_of_legs"</code> that is used by non-abstract methods in the ancestor like <code>"print_number_of_legs"</code>, but is initiated in the descendant class' constructor (e.g. Dog would initialize it with 4 whereas Snake would initialize it with 0). </p> <p>Again, I'm sure there are endless more examples, but basically every (large enough) software that is based on solid object oriented design will require inheritance.</p>
    singulars
    1. This table or related slice is empty.
    1. POWhat’s the point of inheritance in Python?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USRoee Adler
    1. USRoee Adler
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POWhat’s the point of inheritance in Python?
      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. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COFor the first case, it would mean that you are checking types instead of behavior, which is kind of unpythonic. For the second case, I agree, and you are basically doing the "framework" approach. You are recycling the implementation of speak_twice, not only the interface, but for overriding, you can live without inheritance when you consider python.
      singulars
      1. PO
      1. USStefano Borini
    2. COYou can live without many things, like classes and functions, but the question is what makes code great. I think inheritance does.
      singulars
      1. PO
      1. USRoee Adler
    3. CO@Stefano Borini - It sounds like you're taking a very "rules-based" approach. The old cliche is true though: they were made to be broken. :-)
      singulars
      1. PO
      1. USJason Baker
 

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