R0uter's Blog

Not all of the dynamic

we all know，The method is put in the running instance。That is the result of the implementation of the method is based on the instance property came，The property is an example of the current state of change - we call it "dynamic"。

But really all it is dynamic? In fact, not，Some methods give results which will directly and according to your call，It does not need to change according to the change of the instance attribute-that is to say, it will produce a definite result anyway，We call such methods static methods，It is static。

Let's take a look：
[crayo[……]

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In front of so many bedding，Now finally we want to address this thing the garbage collector。

ARC

This is not the Ark ...... This is automatic reference counting (Automatic Reference Counting)，This thing is used to manage Apple memory。

Its function is that the garbage collector on the garbage heap。It would not have been able to ensure that all heap objects that reside in the running to be released in the heap。It ensures that memory will be reallocated to other objects to be used。

What is released

Speaking of the object will not be taken away to the garbage collector，Then it depends on the citation meeting[……]

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At the end of the previous lesson，We finally made clear the process of creating an object，Then，Speaking create an object looks like is to call a method，This method may in the end what is it?

Initializer

Not wrong，When we initialize a class object when，We did call a method - initializer。

Initializer method is actually a special provision of the，It is possible for the class to initialize。

Let's imagine，If no initializer，So we call the class will certainly be stereotyped，Every time they have to create an object，Then modify its properties?[……]

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It's time to look at the living space objects and methods - and want to learn object-oriented，I do not know where to put the methods and objects is a very embarrassing thing - after all, we still have to face the garbage collector，Want to make the garbage collector to help you do more，We have to understand its working mechanism to some extent，Learn how and where to store objects，if not，You have to write a program to the vulnerable!

We have already mentioned the basic concept of the heap in front of the course which，Yes，Objects (instances) is placed on the heap - I put it vividly described as "garbage"。

Be piled[……]

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Last time we mentioned agreement，But we talk about it the way an application，This lesson we take a deeper look at this class and used up almost exactly what profound esoteric protocol。

Now，We again review the shameful inheritance tree once：

Here we wrote a weapon ...... is used for attack and defense。Then，As a game，Model weapons can not just only in one place，Otherwise development costs will be too high - we want to drain as much as possible the value of the code。

Communicate with the designers of our future，designers want[……]

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Rewriting said method，We come back to look at the inheritance tree：

This should look okay，We can create an instance of the sword，Create an instance of a pistol ......

But if I have to write it?

So the question is：excavator……

Do not，Our problem is "weapon" in the end is what?

We say "animal"，Man is an animal，Birds are animals，dog、Cats are animals，That there is no animal animals?

The answer is no[……]

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Said so many times rewriting，This time we have to rewrite treat seriously what method。

contract

We say，Inheritance is the equivalent of signing a contract，We inherited out of the subclass must comply with this contract，So even if you want to do something where no contract，Must comply with contract specifications，so，You override methods，It must also comply with the type of process。

We talked about the type of approach，It ()->() This represented。so，Overridden method must also comply with this type of argument that is receiving the return parameter type to be the same as the name of the same ...... Need I say more?[……]

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We finished the last lesson inheritance，That this lesson we will continue in-depth，What to look at inheritance tree is big move。

You and I could talk about this polymorphic pronunciation，Your first thought should be a high school biology talked of "polypeptide"；Ok，The only possibility is to pronounce the same between the two。

Inherited significance

We say that to achieve the extraordinary significance of inherited，It greatly reduces the number of redundant lines in our code，Reducing the difficulty of maintaining the code ......

In fact，I did not mention the inherited another sense - Contract。

A lesson we did a Demo，On behalf of the subclass inherits the parent class to get[……]

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Last time we specifically about the inheritance mechanism，And also designed an inheritance tree，So the question is：I'm not going to ask Excavator strong Which? I want to ask how to determine whether a class is a subclass of another class do? How do we design a class instead of a class of attributes?

"A" and "a"

Here we will use such a method to examine the relationship between the two of them：

we say，Pistol firearms --OK，no problem，So pistol This class is a subclass of firearms。

There is a sword sword，It is a cold steel - no problem，So that[……]

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