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#1 rule: don't define an interface until you have more than one implementation

Johnny Sins is truly a modern polymath!

Something to point out - a BIG difference from other programming languages - is that the type (in this case CR7, Messi or FootballPlayer) does not explicitly implement the interface as it would for example, in C# or Java where the class declares implementing it. Instead, it is enforced by the Go compiler which checks the function to be declared for the type.

THANK YOU again, Anthony, for demystifying complex concepts, with easy-to-understand real-world analogies most people can relate to!

The last part of the video where you added Name() was so important to understand and grasp the "contract" analogy fully, good vid

After 7+ years of senior python thinking for me this was the 'AHA' moment right here: " team := make([]Player, 11) for i := 0; i < (len(team) - 2); i++ " I was like 'what???, you can loop over a slice of "capabilites", not just actual objects???" I think this opens a whole range of different design ideas, way of decouplig, testing, etc. Cos you're focusing on the capability, not the object / instance or whatever. Now the term 'contract' makes a lot more sense. Because you are saying, hey I don't care WHAT you are as long as you CAN DO this or that. BTW, thanks a lot Anthony! In addition to the depth of your (applicable real life) knowldge I really like your style. Feels likehaving a coding conversation in pub w. a beer. :)

This clears things up for interfaces with GO. Keep up the good work !

I'm just discovering this channel and I got suscribed just right now! Good job my man

Just in time when I started to face the problem of understanding interfaces in go. Thanks, you really helped me

How I think of an interface is that it is a struct but for functions. So while a struct describes what properties an "object" has, and an interface defines what functions an "object" has, though not only limited to those functions. So as long as your object has all the functions in the interface, it implements that interface. Meaning if you have a function or method that only works at an interface level, that "object" is a valid candidate.

Interfaces are the only thing I struggle with in Golang (well, that and channels/concurrency)

it definitely helped me out to understand interface better thanks a lot

You're the most enthusiastic and incredible! Well you got it, INCREDIBLE golang guru I have ever watched in youtube! you deserve millions of subs, bro!

Love your videos man. Thank you for making the best videos on golang

I find that the biggest problems with interfaces in Go is that people have pre existing ideas for how they should be designed, ie defining the interface first with the implementation. In Go you don't do this, you define an interface where you want to use it. Because they are implicit rather than explicit it's almost a complete reversal of thinking, and it catches a lot of people out.

Thanks for this! You gave me that big AHA and thumbs up for using VIM 🎉

If I ever find myself in Belgium, I'm gonna reach out to meet up. You're the man.

Hello, mate I extremely love ur content. I was curious about ur course (despite the price), so had a look into it. As a dev with 7 months of commercial exp in go (microservice architecture) (2,5 years overall) I can tell ur course (imho) lacking very important aspect (from the glance to the full course description) - and it's work with DB. Especially, when u need to do bunch of aggregations, hit the endpoint from one service to another, sending bunch of some data to sync and upsert relative data in the db of the other microservice, etc. etc. Mb I'm wrong and didn't notice that in the list, but without this I reckon course isn't complete at all. Anyways, thanks for what u r doing.

Hi Anthony, I'd like to ask you, why did you move to vscode from nvim? Just curious.

I think the explanation is decent, but i do also think it would be beneficial to have a followup where you truly see the benefits of interfaces. Maybe in combination with a strategy pattern where it's commonly used. Strategy patterns are pretty mandatory to understand as a professional developer imo. It's where i learned to understand interfaces, as it's a perfect place to use it.

Hi Anthony, hilarious thumbnail, made me chuckle! Love your content :)

This is a great video, good job!

This example is clears my entire doubt about the interface in golang. Thank you ❤

Hi Anthony, how do you use rand without seeding?

Great video!

I personally think the biggest "gotcha" with learning interfaces coming from different languages is the dual behavior they have: either as a type constraint, or the traditional "thing that implements", but not both simultaneously. You can use an interface as a field in struct if it implements functions, but if you change it to a type constraint, it no longer works. When I was initially learning Go, this was unexpected to me.

do you think you could make a video on tui on a telnet/ssh server? im currently trying to make a casino for fun so me and my friends can play but i cant seem to make any good tui for instance i cant get it to work on the ssh server

This video was included in the recommendation of Go Weekly

What theme are you using on VSCode. Looks very sleek!

This made me understand golang interfaces! +1

Ive been binging many of your Golang vids and find em really helpful. Thanks for your tips and insight Anthony. btw anyone know what vscode theme he's using?

Thank you! That did help a lot. I was wondering if I could do something better because I almost never declared my own interfaces. I actually calmed down a bit because a lot of my code is very interconnected with the database...and my logic used interfaces that were already made for me by the db engines and stuff

U are my best teacher 😊

I think the confusion primarily comes from Go interfaces being more descriptive than prescriptive. You don’t declare you are implementing an interface for a type, so there is no checking whether a type actually implements it until you try to use it as interpreted by the interface.

Are you using some kind of Vim plugin for VSC? You're super fast with. Any hints on getting that good at text/code editing?

can you make a video with practical use of interfaces?

Anthony I have a question if I made a receiver function on a struct which is global access but my struct is private so how do I unit test that

Great video.

Good one

This is how it looks without interfaces, As you'll see, it becomes messier and less scalable. package main import ( "fmt" "math/rand" ) type Rolando struct { name string stamina int power int sPower int } type Messi struct { name string stamina int power int sPower int } type FootbalPlayer struct { name string stamina int power int } func KickBallExample(player interface{}) { switch p := player.(type) { case Rolando: shot := p.stamina + p.power + p.sPower fmt.Printf("%sshot: %d ", p. name, shot) case Messi: shot := p.stamina + p.power + p.sPower fmt.Printf("%sshot: %d ", p. name, shot) case FootbalPlayer: shot := p.stamina + p.power fmt.Printf("%sshot: %d ", p. name, shot) default: fmt.Println("Unknown player type") } } func main() { team := make([]interface{}, 11) for i := 0; i < len(team)-2; i++ { team[i] = FootbalPlayer{ stamina: rand.Intn(10), power: rand.Intn(10), name: "random", } } team[len(team)-2] = Rolando{ stamina: 10, power: 10, sPower: 10, name: "Ronaldo", } team[len(team)-1] = Messi{ stamina: 10, power: 10, sPower: 8, name: "Messi", } for i, player := range team { KickBallExample(player) } }

In your other video you have said that we should not create a lot of files. But I think it would be perfect to place CR7, Messi and FootballPlayer into different files (if for instance they had larger logic inside). Isn't it?)

best Golang teacher ever

14:26 Roberto Carlos, 14:29 Arjen Robben. I am from the time of these people's. 13:48 Belgian goalie. I was there as well, coz I used to study in Belgium. This is a good video, catching my past.

Well I am from a third world country. The pricing of your course is basically more than half my salary. If it was on udemy at a low price I would buy it. Or if it was 15-30$ a month I would buy it. I love your style. thanks for the youtube videos.

Good tutorial.

What is your vscode theme?

Hey Anthony, I've recently been getting your video suggestions on YT since I just started with Golang. I don't if anybody has mentioned this to you, But in your video the voice is very low. Please check it out and thank you for the knowledge you share.

Hi guys! can someone explain to me why rand.Intn(10) return values greater than 10?, it should return a value between (0,n) but no greater than, right?

thanks

what's Anthony's vs code theme?

😂😂😂😂 The ronaldo love was too funny

sorry i don't code in Go but how can you allocate an Interface instead of a struct? how does it even know the size of what it is allocating? in order for this to work, Go is doing some wild magic behind the scenes. Maybe it allocates a base struct with virtual methods? This seems pretty bad for performance and other things.

Weather it is handler function or webserver or service layer or repo layer mocking everything

In soccer if you have only 11 players, even the ones with shot 1 will stay off the bench for the whole season ;-) 🙂

I just wonder, all the base calculations are the same. Power + Stamina. So can you abstract that to something and apply that to all. So kickBall = getBasePower on the FootballPlayer and on CR7 kickball = getBasePower * SUI

thank u, but it would be more usuful if you can show how interfaces and structs present in 3rd party packages can be used in your own application and the patterns potentially be used

Always thought Arjen Robben was a Rust guy

You can even let your mom enter the football team as long as she can 'KickBall()' She isnt even a football player, but it doesn't matter ;-)

mutexes locking, DELTS POPPING

❤

Thank you Anthony, great video but for some reason every time CR7 getting higher score than Messi Go seems to Panic.

You know the "append()" function exist 😂

So we make a slice with a type Player and populate that slice with FootballPlayers and nowhere else we tell the program that football players are indeed players? Snap jij het nog?

First thank you for your passion it is great to show how much fun developing is. But your code is not a good example. If you have a slice you should use range. To use for, looks a little bit like old JavaScript to me. Also the explanation of the interface is how interfaces works in general. It is a good explanation, but it does not cover the Go specific approach. The goal of defining an interface is that the consumer can define the interface. If you have a function "kickIt(players []player)" the kickIt-package can define the interface. The packages "basketball", "americanfootball", "soccer" even don't need to know that there is an interface. There is not "type a implements interface player" in Go. This makes the packages more flexible.This is the idea of interfaces in Go.

it doesn't seem easily scalable. add one function to the interface and now you have to make potentially dozens of changes.

😂😂Got to learn with comedy characters! CR7 and Suuuii Fked Little less messi 🤣 15:41

Voetbal😂 i catch u slacking again brodie

Can we Indian’s have a discount over this 250 dollar price, because of Purchase power parity this amount is little expensive for students to buy?

Love your channel, you know what i mean?

Do CONTEXT next

Next video, explain crazy function with interface interface * wtf

Thank you johnny sins XD

U should train more

Explanation was spot on but you don't get my like for suggesting Ronaldo's shots were more powerful than Messi's. Just joking.

how is that Messi SUI, probably the greatest player in history, is lower than CR7? c'mon!

Course is still pricy :/

Please make a full fledge unit test , integration test on all possible scenarios

i found a big mistake in your video, Messi>ronaldo.

to much time for small concept

suiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii

i get it so cr7 is better than messi 😂

You are a smart guy and have great point in your videos. But the problem I have with it, after spearing more than 20 minutes snatching this I realized that you lost a lot of my time. You could explain this concept in less that 10 minutes without losing quality. Please make your videos shorter. This is why but the end of this video I lost interest to purchase you choose. If you talk so much empty words there I'll lose a lot of time. I do not want to pay someone to entertain me. I need knowledge. And I'm an sorry, no one will tell you that nowadays, but you are not that funny, but you are defensively very experienced developer. This is you doing past. Lean on it.

bla-bla-bla... I am here to learn how to code GO, not to listen to a parrot.

The interface paradox I face when developing a feature, "when to implement an interface?" ... 🫥