Oop exercise #416

OlexiyDobroskok · 2022-09-03T13:07:11Z

OOP exercise

Demo |
Code base

The code is submitted in a dedicated feature branch.

Only code files are submitted.

Please, review.

github-actions · 2022-09-03T19:04:39Z

Hey!

Congratulations on your PR! 😎😎😎

Let's do some self-checks to fix most common issues and to make some improvements to the code before reviewers put their hands on the code.

Go through the requirements/most common mistakes listed/linked below and fix the code as appropriate.

If you have any questions to requirements/common mistakes feel free asking them here or in Students' chat.

When you genuinely believe you are done put a comment stating that you have completed self-checks and fixed code accordingly.

Also, be aware, that if you would silently ignore this recommendation, a mentor can think that you are still working on fixes. And your PR will not be reviewed. 😒

A Tiny JS World -- OOP exercise check list

Relates to A Tiny JS World OOP exercise.

Check-list - definition of done

Minimal requirements to meet:

Optional level up (not required to implement):

Friends list is a list of objects refs rather than names (strings)
Cat-woman class is built employing composition rather than inheritance only

Bonus:

toString magic method; when implemented print(inhabitant) does the job as .toString is called implicitly
this.constructor.name; when used for output then no need to store species property

Helpful resources:

Universal recommendations:

Give variables and functions meaningful names. Avoid generic names like item, element, key, object, array or their variations. Exception: helper functions that are specifically and intentionally designed to be multipurpose.
Function names should start with a verb as they denote actions; variables are normally nouns; boolean variables/functions start with is, does, has etc; variable containing multiple entities and functions returning lists contain entity name in plural form.
Have consistent code style and formatting. Employ Prettier to do all dirty work for you.
Use common sense or seek for an advice whenever requirements look ambiguous or unclear.

Also take a note of the requirements above and follow them in all your future projects.

By the way, you may proceed to the next task before this one is reviewed and merged.

Sincerely yours,
Submissions Kottachecker 😺

OlexiyDobroskok · 2022-09-13T17:26:42Z

Made a self-test and looked at the task from a new perspective)

OleksiyRudenko

@OlexiyDobroskok a really good job!
A few improvements and we are done.

OleksiyRudenko · 2022-09-20T17:34:27Z

submissions/OlexiyDobroskok/OOP_exercise/index.js

+    super({ species: "human", name, gender, saying, friends });
+    this.hands = hands ?? humanDefaultProperties.hands;
+    this.legs = legs ?? humanDefaultProperties.legs;
+  }


Why not just to set default value the same way it is done for species?
This is not a rhetoric question.

I’ve overdone the default values a little bit. =))

OleksiyRudenko · 2022-09-20T17:35:58Z

submissions/OlexiyDobroskok/OOP_exercise/index.js

+  addFriend({ name }) {
+    this.friends += name + "; ";
+  }


From the requirements:

Friends list is a list of objects refs rather than names (strings)

OleksiyRudenko · 2022-09-20T17:38:16Z

submissions/OlexiyDobroskok/OOP_exercise/index.js

+class CatWoman extends Woman {
+  constructor({ name, saying = "", friends, legs, hands }) {
+    super({ name, saying, friends, legs, hands });
+    this.saying = Cat.meow + " " + saying;


Use static property is a good start in the right direction.
But here is the problem: if we change cat's defaut meow (which is allowed by Cat class API), cat-women's saying will be out of sync. Can you devise a way to bind their saying more tightly? You are only one step away from the solution.

@OleksiyRudenko The easiest way I see is to assign a default value to the static property of the cat:

Cat.meow = "¡miau miau";
this.saying = Cat.meow;

but then all cats lose their identity and it makes me sad =)))
Is this the right way?

As long as property holds a primitive value the tie is weak, i.e. simply copied once. Strings, numbers and booleans are primitives. We need something that is passed by reference. These are JS objects (arrays and functions are also objects). Class methods can also be static. There are also very specific methods - getters and setters.
Given the above find a solution that will help to both meet requirements and minimize impact on code to keep it readable (i.e. we do not want dogs and humans to have added complexity just becase we need to resolve a matter between cats and cat-women).

@OleksiyRudenko Tried to bind Woman and cat by static method. Looks strange)

It does. Truth is that hybrids do not fit OOP hierarchical nature really well.
Composition is a better pattern in similar cases.
The purpose of this part of task was exactly to see the weirdness of how it has to be implemented in OOP paradigm.

@OleksiyRudenko Good task. At a glance nothing difficult, but on the small details forces to revise a lot of materials). Do I still have to make some adjustments to the task?

OleksiyRudenko · 2022-09-20T17:39:33Z

submissions/OlexiyDobroskok/OOP_exercise/index.js

+const inhabitantDefaultProperties = {
+  species: "No species",
+  name: "No name",
+  gender: "No gender",
+  saying: "Hello",
+  friends: "",
+};
+
+const humanDefaultProperties = {
+  hands: 2,
+  legs: 2,
+};
+
+const petsDefaultProperties = {
+  paws: 4,
+};


It would be a better approach to have defaults within class definitions. Not necessarily in form of explicit const definitions. KISS

OleksiyRudenko · 2022-09-20T17:40:56Z

submissions/OlexiyDobroskok/OOP_exercise/index.js

+    this.gender = gender ?? inhabitantDefaultProperties.gender;
+    this.saying = saying ?? inhabitantDefaultProperties.saying;
+    this.friends = friends ?? inhabitantDefaultProperties.friends;
+    Inhabitant.worldPopulation.push(this);


Not a good idea to populate world from within inhabitants.
There is a Factory pattern in SW design, but this is not the case.

Not a good idea to populate world from within inhabitants. There is a Factory pattern in SW design, but this is not the case.

Can I create a separate function that will create and push objects into an array?

Yeah. Creating World class would be an overkill at this stage of project development.
But please avoid .push. Array methods provide more semantic ways to solve this.
And you will probably want to help inhabitants make friends after they are born. At least exisiting inhabitants cannot make friends with those who are not born yet.

I abandoned this idea because it was originally intended to simplify the creation of the world, but Later there are problems with withdrawal of friends.What method can you recommend to replace the push?It seemed to me very convenient to work initially with an empty array. (

I reviewed this fragment. I agree that .push is a way to go.
The only thing remains: it is a world that consists of Inhabitants rather than world is a part of any Inhabitants.
Sure, syntax allows us to do this and make a static prop looks attractive. But having world as a part of inhabitant is counter-intuitive.
World can be a collection of inhabitants. Simplest collection is JS array. If we wanted some world-wide operations we would have multiple functions for those operations and it would make sense to scope them under class World.

Changed the default parameter settings; Removed the static method of creating world in a inhabitant;

OleksiyRudenko

@OlexiyDobroskok nearly there.

OleksiyRudenko · 2022-09-26T16:35:25Z

submissions/OlexiyDobroskok/OOP_exercise/index.js

+
+  introduceYourSelf() {
+    if (this.friends.length === 0) {
+      this.friends = "Looking for friends!";


What will happen if we .addFriend after first call of .introduceYourSelf?

@

What will happen if we .addFriend after first call of .introduceYourSelf?

@OleksiyRudenko Instead of an empty array, I get a string...) Done)

OleksiyRudenko · 2022-09-26T16:36:02Z

submissions/OlexiyDobroskok/OOP_exercise/index.js

+      return `<strong>${this.saying}! My name is ${this.name}. Species: ${this.species}. Gender: ${this.gender}. Friends: ${this.friends} </strong>`;
+    }
+    const friendsName = this.friends.map((friend) => friend.name).join(", ");
+    return `<strong>${this.saying}! My name is ${this.name}. Species: ${this.species}. Gender: ${this.gender}. Friends: ${friendsName}. </strong>`;
+  }


This fragment can be made DRY.
Optimize this method.

This fragment can be made DRY. Optimize this method.

done

Fixed bug with adding friends.

OleksiyRudenko

@OlexiyDobroskok well done!

OleksiyRudenko · 2022-09-26T20:54:58Z

submissions/OlexiyDobroskok/OOP_exercise/index.js

+    const template = `<strong>${this.saying}! My name is ${this.name}. Species: ${this.species}. Gender: ${this.gender}.</strong>`;
+    if (this.friends.length !== 0) {
+      const friendsName = this.friends.map((friend) => friend.name).join(", ");
+      return template + `<strong>Friends: ${friendsName}.</strong>`;
+    }
+    return template + `<strong>Friends: Looking for friends!</strong>`;


You have something for any situation about friends (0 or non-zero number of friends).
const friendsName = this.friends.length ? this.friends.map((friend) => friend.name).join(", "); : "Looking for friends"
Now you can have a single return statement. Altogether 2 lines of code for this method.
Feel free searching for ternary operators and/or seek for explanation in Students' chat.

Ternaries are helpful, you will use them often. Worth mastering them.

@OleksiyRudenko Thanks. Looks cool) Need to look at ternary operators.

OlexiyDobroskok added 4 commits September 3, 2022 11:56

OOP_exercise task

bb9688f

delete comment

60ab98c

Friends list is a list of objects refs

f8e33ab

delete comments

611b213

OlexiyDobroskok force-pushed the OOP_exercise branch from 344e1c1 to 611b213 Compare September 3, 2022 13:09

A-Ostrovnyy added the task-TJSW-OOP label Sep 3, 2022

OlexiyDobroskok force-pushed the OOP_exercise branch from 7fe36e3 to 611b213 Compare September 13, 2022 17:20

New Perspective on the Task

5f342e5

OleksiyRudenko added the self-check-done Student confirmed that self-checks against requirements/common-mistakes are done label Sep 20, 2022

OleksiyRudenko self-assigned this Sep 20, 2022

OleksiyRudenko requested changes Sep 20, 2022

View reviewed changes

Tried to make a woman and a cat friends;

21c4ad9

Changed the default parameter settings; Removed the static method of creating world in a inhabitant;

OlexiyDobroskok requested a review from OleksiyRudenko September 21, 2022 17:05

OleksiyRudenko requested changes Sep 26, 2022

View reviewed changes

Made method introduceYourSelf DRY;

c8e3d14

Fixed bug with adding friends.

OlexiyDobroskok requested a review from OleksiyRudenko September 26, 2022 18:16

Correcting strong tag

38a73ef

OleksiyRudenko approved these changes Sep 26, 2022

View reviewed changes

OleksiyRudenko merged commit 1aa498a into kottans:main Sep 26, 2022

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Oop exercise #416

Oop exercise #416

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Oop exercise #416

Oop exercise #416

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OlexiyDobroskok commented Sep 3, 2022

OOP exercise

github-actions bot commented Sep 3, 2022

A Tiny JS World -- OOP exercise check list

Check-list - definition of done

OlexiyDobroskok commented Sep 13, 2022

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