5 minutes into the video and you've made more sense than the last 10 videos I've watched around Go concepts. Incredible approach to teaching while covering real world scenarios. Amazong job. Subbed!
@@edwingarcia5043 That happens too, doesn't it. Great point (if not misplaced)! Most likely, it doesn't materially negate the effectiveness of Francesc's approach. It's a vector field and Rob seemed to clearly be using a short-hand to say, "damn, this vector has a magnitude and direction that helped me."
Very clear explanation, with mental leaps just at the right times. And also blending the real world use cases into the examples is very well thought of. Thank you!
I love the preaching of good practices like not using the context to pass values unless absolutely necessary. This aligns with how I like to write code, even though I've seen other developers use context to pass non-request scoped data. This channel seems to be a hidden gem!
Francesc, I know this is an old Just for Func but I went back and watched it today and wanted to say Thanks! Great episode. As others have said, the explanation is perfect! Just what I needed. Thanks again and keep up the great work!
Thanks for the great video. This video was just the right speed and amount of explanation that I needed, very to the point. Watching you code through the examples, I learned things other than the context package too.
Thank you for this, this is amazing. I have read about context package, but couldn't really understand. But this 36 mins have been priceless. Very well done.
I keep coming back to this video over time. It has a lot of value. Thanks for taking time and doing that. Where are you by the way, get back here and produce some more please.
Great video. A very important concept for setting up and handling things like timeouts and even exceptions in Go. I don't see this being addressed in other Go overview sites/videos. Really happy to come accross this. However, perhaps its just me but I don't think the last point/topic on sending value between "client.go" and "server.go" had appropriate phrasing from @justforfunc. I get his explanation for "foo" id to properly show up, the client has to include it as a header/body/uri-id as they are purely HTTP request data/communication. But that has nothing to do with inherently Go or even "context". I sort of interpreted this context as some internal "Go" communication between the client.go and server.go processes. And really the context in both client.go and server.go are between the those process' and operating system, but something like an HTTP client and server are really good examples to show where "context" is very applicable. Really good video but slightly misleading.
I kept trying sending value with a context over the http to another machine, I stopped after I watched this video. Very detailed! I love your videos :D
thanks, this was a great video! one question i still have is this: i see a lot of talk about not storing contexts anywhere, and only passing contexts around as parameters. i don't have a problem with this, but i wonder why this is so important? what would be some of the unintended consequences of a struct holding a reference to a context? does the same rule apply to cancellation functions? (ok that was more than one question. i'm sorry) cheers!
I was a little puzzled by your suggestion to not use Context values to store information which affects program flow. I mean... I understand the argument, but I fail to see the alternative for HTTP middleware. First, sure, it's a given that it should only be used for request-scoped values and request-id is a prime example. But you recommended to pass request scoped values which affected program flow as parameters. That is of course in general correct for any code, but for HTTP middleware you are kinda stuck with the http.Handler interface (reponsewriter, request). So how would you pass, say, "user id" to a handler you wrap around without creating your own alternative to http.Handler and making your code less composable?
Thanks Frances, was a clear explanation. Can you please do the next episode about package initialization, sharing variables (like db / session) around between packages?
Priceless, as always. What about an episode about how to create applications that work at the same time on multiple servers, as a cluster? The guides I have seen are ambiguous and do not share the good practices they proclaim. That, or an episode about when it is recommendable to create gorutines and when not. Thank you, Francesc!
JustForFunc yeah, a cluster database, a load balancer, a proxy to redirect http traffic, or a massive scanner which distributes traffic between available servers (my original idea was something pretty similar to this) and when it finalizes, joins results. Thank you!
Hi, I would love to hear from you, as someone with a lot of experience in Golang, do you think SOLID Principles important in practice, and in interviews? Would I be asked a lot of questions, and how would I go about that, considering that SOLID Principles are mostly OOP concepts, and Golang is not a real OOP language. I am also curious about the same for design patterns like Builder, Factory pattern etc
Regarding the ability for the HTTP client to "cancel" the request via the context which notifies the HTTP server, I assume this would only work with such a golang client and a golang server, correct? I.e. this is impossible with say a Java client and golang server, correct?
Hi, looks like using context.WithTimeout somehow tears down TCP half-connection from client to server, that's why you got context closed on the server side. I didn't get how it closes the half-connection. But the question is why context.WithCancel does not tear down TCP half-connection after invoking cancel() ?
Learned Context in one go, without even pausing a single sec. :) btw which editor you are using and i saw you have some template like hand -> f(w http.Responsewrite, r *http.Request), how to do it?
what will happen if the both the parent routine and child routine cancel the context at the same time. and if the parent routine has more than one routine like Ca and Cb for example, both the Ca and Cb use the context from parent routine P, if the P cancelend, both Ca and Cb will canceled? if only Ca canceled, then P and Cb will not be notified ?
The select statement waits for a channel to return a value, unless you have a default case. Having a default case implies you're doing some work and will come back to check the channels again, in which case your select would be wrapped in a for loop to enable it to be called again. Otherwise you only care about whichever channel returns data first, say a timeout or a cancel.
Hi, amazing stuff! I was still struggling on how to use context skimming the official docs. However this is simply awesome. Especially thanks for showing that you can't send context values across network.That would be stupid idea anyway :-)
useing a function (sllepAndTalk) you created for half of the video ,and not showing how that function worked was a waste of my time. thank you for frustrating me back to the doc.
Who's here from the Aug 20th Go Time podcast? BTW at 21:00 - since go1.13 - you can now do this in one call with: golang.org/pkg/net/http/#NewRequestWithContext
I really, really, really would like to see complete series about how to create IDIOMATIC Client Server WEB application with most common CRUD operations using gRPC and MySQL. Client and Server should be just simple Go programs. Would like to see: IDIOMATIC Directory/File organization in context of github.com/myusername/. gRPC service interface, and message/+field idiomatic naming and organizing into packages. Package +nested package importing. Compiling nested .proto's. TLS secured gRPC communication. Idiomatic endpoint URL constructions. Context. Displaying in browser - single record, list of records, single record + list. Submitting form, updating record, creating nested records - like, when customer is created, also some log record in the same DB is created pointing to the same customer (tx). And so on so on. Basically, EVERY beginner want to see complete IDIOMATIC example of writing production ready basic DD web-page. Nobody is teaching this. 98% of tutorials and books teaching the easiest way - Just mess everything into main.go and use mock data! This is total BS! This is not how good things should be teached. It is much better when you see, how great foundation looks like and then starting to tweak, and to learn all those used patterns in details. When you have no context in head, it is impossible to learn right way. Iterating thru the trial & fail is way to learn for sure, but it is not the most effective! It just wastes too much human time. YES - this kind of tutorial will take time to record. But this will be the SINGLE PERFECT TUTORIAL in the whole f*g WEB.
@@JustForFunc They are like middlewares. It does come with the standard grpc package. github.com/grpc/grpc-go/blob/master/interceptor.go. The standard package has a big limitation. Middleware/Interceptor Chaining is not allowed. There are third party packages to accommodate chaining. This one is pretty popular --> github.com/grpc-ecosystem/go-grpc-middleware The concept looks very simple but it might get a little confusing when you dive deep into it. Would be helpful if you make a video. Thank you :)
@@JustForFunc Exactly. I understand there are quite a few documents (should I say incomplete documents) on the internet where people keep comparing interceptors to middlewares, explain the differences between the standard grpc interceptors and go-grpc-middleware but do not go into the details. For someone who already know the basics of grpc, interceptors in grpc is a great way to advance his/her knowledge. The way you explain things is priceless, so thought of requesting you to do a video on it :-).
![Seungmin "그렇게, 천천히, 우리(As we are)" | [Stray Kids : SKZ-PLAYER]](http://i.ytimg.com/vi/kAzmhLHePqU/mqdefault.jpg)
5 minutes into the video and you've made more sense than the last 10 videos I've watched around Go concepts. Incredible approach to teaching while covering real world scenarios. Amazong job. Subbed!
What makes you think that the other videos didn't help you to get ready for watching this one video? 🤔
@@edwingarcia5043 That happens too, doesn't it. Great point (if not misplaced)!
Most likely, it doesn't materially negate the effectiveness of Francesc's approach. It's a vector field and Rob seemed to clearly be using a short-hand to say, "damn, this vector has a magnitude and direction that helped me."
Very clear explanation, with mental leaps just at the right times. And also blending the real world use cases into the examples is very well thought of. Thank you!
Wow, that's such a nice thing to say!
Thanks 😊
I’ve been learning go for less than a week, and just encountered your channel. Sad to see you no longer upload, these videos are really good.
I love the preaching of good practices like not using the context to pass values unless absolutely necessary. This aligns with how I like to write code, even though I've seen other developers use context to pass non-request scoped data. This channel seems to be a hidden gem!
Kind of got scared by the video length at first though, glad I watched it anyways.
From time to time I come back here and watch a random video. It inspires me so much. Thank you.
Amazing explanations with examples. One of the most talent instructors.
Thanks you and keep doing it.
Thank you! I don't understand why no one starts by giving simple example like you do
Francesc, I know this is an old Just for Func but I went back and watched it today and wanted to say Thanks! Great episode. As others have said, the explanation is perfect! Just what I needed. Thanks again and keep up the great work!
This video is my go to reference material on go's contexts. Thank you very much
thanks Frances, the quality of this video and its contents is exceptional :-)
Great video! I watched 2 talkes before and was more confused about contexts after watching them.
this video explained everything!
i read a lot of posts on medium and the GO blog about context and i was completely lost... with this video it was very easy to understand. Amazing job
Thanks for the great video. This video was just the right speed and amount of explanation that I needed, very to the point. Watching you code through the examples, I learned things other than the context package too.
I really enjoyed this episode - thank you! I've seen context used a lot and never really understood it until now. ❤️
Best video on the topic. Thanks
Thank you for this, this is amazing. I have read about context package, but couldn't really understand. But this 36 mins have been priceless. Very well done.
I keep coming back to this video over time. It has a lot of value. Thanks for taking time and doing that. Where are you by the way, get back here and produce some more please.
Great video. A very important concept for setting up and handling things like timeouts and even exceptions in Go. I don't see this being addressed in other Go overview sites/videos. Really happy to come accross this.
However, perhaps its just me but I don't think the last point/topic on sending value between "client.go" and "server.go" had appropriate phrasing from @justforfunc. I get his explanation for "foo" id to properly show up, the client has to include it as a header/body/uri-id as they are purely HTTP request data/communication. But that has nothing to do with inherently Go or even "context". I sort of interpreted this context as some internal "Go" communication between the client.go and server.go processes. And really the context in both client.go and server.go are between the those process' and operating system, but something like an HTTP client and server are really good examples to show where "context" is very applicable.
Really good video but slightly misleading.
I wonder how many developers would recognise "modern bear" t-shirt. Thanks for fueling up my desire to learn Go! Woof 😋
I kept trying sending value with a context over the http to another machine, I stopped after I watched this video. Very detailed! I love your videos :D
very timely upload. was just playing around with this today and i wasn't quite sure if i was using it properly. thank you!
I hope it will help you! Feel free to ask any questions at the end :-)
thanks, this was a great video! one question i still have is this: i see a lot of talk about not storing contexts anywhere, and only passing contexts around as parameters. i don't have a problem with this, but i wonder why this is so important? what would be some of the unintended consequences of a struct holding a reference to a context? does the same rule apply to cancellation functions? (ok that was more than one question. i'm sorry)
cheers!
I was a little puzzled by your suggestion to not use Context values to store information which affects program flow.
I mean... I understand the argument, but I fail to see the alternative for HTTP middleware.
First, sure, it's a given that it should only be used for request-scoped values and request-id is a prime example.
But you recommended to pass request scoped values which affected program flow as parameters. That is of course in general correct for any code, but for HTTP middleware you are kinda stuck with the http.Handler interface (reponsewriter, request).
So how would you pass, say, "user id" to a handler you wrap around without creating your own alternative to http.Handler and making your code less composable?
Thanks Frances, was a clear explanation.
Can you please do the next episode about package initialization, sharing variables (like db / session) around between packages?
Loved this video. Watched a few that didnt quite get through, but this really brought into the right “context” xD
I'm so glad I found your RUclips channel ! This video is perfect to understand how to use the Context package, thx !
Amazing explanation with real world examples. Thank you so much!
Great video. I'd been reading about context this afternoon and this very much tied up some mental loose ends I still had.
Priceless, as always.
What about an episode about how to create applications that work at the same time on multiple servers, as a cluster? The guides I have seen are ambiguous and do not share the good practices they proclaim.
That, or an episode about when it is recommendable to create gorutines and when not.
Thank you, Francesc!
+Miguel Ángel Jimeno Arce can you give an example? Do you mean something like a cluster database?
JustForFunc yeah, a cluster database, a load balancer, a proxy to redirect http traffic, or a massive scanner which distributes traffic between available servers (my original idea was something pretty similar to this) and when it finalizes, joins results.
Thank you!
Hi, I would love to hear from you, as someone with a lot of experience in Golang, do you think SOLID Principles important in practice, and in interviews? Would I be asked a lot of questions, and how would I go about that, considering that SOLID Principles are mostly OOP concepts, and Golang is not a real OOP language. I am also curious about the same for design patterns like Builder, Factory pattern etc
lets say about following the trace-id and span-id, both are probably good values for contexts right?
What's the != symbol at @15:46? Shouldn't it be !=?
Regarding the ability for the HTTP client to "cancel" the request via the context which notifies the HTTP server, I assume this would only work with such a golang client and a golang server, correct? I.e. this is impossible with say a Java client and golang server, correct?
Thanks so much! 7 minutes in and I now understand what the code does that I was trying to decipher.
I am big fan from China who watch your video every day before sleep! 😀
Thank you Frances, it’s really help me to understand context package.
Do you have any other example for context with value other than request id? It would be better to understand this concept if you can. Thanks!
Excellent explanation. This is very helpful. Thank you!
Thank you, you're REALLY doing well. Thank you one more time!!!
Nice vscode setup. Can you describe the exact set up somewhere in a post or video?
I've been learning so much watching your videos! Thank you very much.
Hi, looks like using context.WithTimeout somehow tears down TCP half-connection from client to server, that's why you got context closed on the server side. I didn't get how it closes the half-connection. But the question is why context.WithCancel does not tear down TCP half-connection after invoking cancel() ?
This helped me understand the context package much better, thank you!
This is some good quality content!
where can I find the codes which are written here?
I got a doubt. When u write a handler with select case, context will be cancel only because your time.After are holding execution and than
I got it!! It will be able to run on a different goroutine returning value and catch it into select statement
how do I set up visual studio to add the package library while I writting code? I always need to do it for myself and is anoying
Learned Context in one go, without even pausing a single sec. :) btw which editor you are using and i saw you have some template like hand -> f(w http.Responsewrite, r *http.Request), how to do it?
Hey. Now I know more about context. I never thought that I have context in net/http package and it was a surprise for me. Thank you!
What vscode theme is this?
One of the best explanation!!! Thanks.
Beautiful, Excellent, Mind Blowing, Priceless
Really enjoyed the explanation, very clear 👍🏽
Nice, learnt allot. PS can you also give the reason behind values not propagating like cancel please?
Please keep the good work up. So good.
Amazing... Short and sweet!
That's what i needed.
BIG THANK YOU
Really nice, clear my head lots on this package
where is the sleepAndTalk fn ?
what will happen if the both the parent routine and child routine cancel the context at the same time. and if the parent routine has more than one routine like Ca and Cb for example, both the Ca and Cb use the context from parent routine P, if the P cancelend, both Ca and Cb will canceled? if only Ca canceled, then P and Cb will not be notified ?
Closing a channel doesn't notify a single receiver (unlike sending elements) instead it unlocks every goroutine blocked receiving from it
many thanks,after watch your next episonde(implement the context), I got it!
phenomenal explanation, thanks!
Hey, very nice video! Could you make an episode about you vscode setup and the extensions you are using? Thanks!
You've done a great job ! You're accent is very clear for a frenchie like me
Merci beaucoup, je fais mon mieux
Francesc, Did you do the episode on the internals of the context package?
Yup, literally the episode after this one
Really informative video. Thanks Francesc.
Really helpful video, thank you dude, keep up the great work!
Couldnt figure out what you did in the Decorate. I think I need some sleep..
it was basically a middle ware which adds in a request id into the context and returns the next function as a call
Disclaimer: kinda new to golang XD
What do you mean by "defining a request without using tags?"
How come this code works even though the select isn't in a for loop?
The select statement waits for a channel to return a value, unless you have a default case. Having a default case implies you're doing some work and will come back to check the channels again, in which case your select would be wrapped in a for loop to enable it to be called again. Otherwise you only care about whichever channel returns data first, say a timeout or a cancel.
@@DudeMcDuderson That helped a lot, thanks Dude!
@@DudeMcDuderson Thanks a lot.
Very nice explanation! Thanks
Very clear, as always, GO on
I have no idea about how the function sleepAndTalk know we cancelled
I had the same question. So, I googled this: gist.github.com/astenmies/2f180213d310aa16b4b8c4e637be9441
@@KotBinary thanks :)
Exceptional work!
Amazing explanation! thank you so much
Incredible talk.
Learning Golang from Bayer Mayfield. The best
which font you use?
it's github.com/tonsky/FiraCode
github.com/tonsky/FiraCode
You sure? Sure looks a lot like Source Code Pro [github.com/adobe-fonts/source-code-pro]
Yes, Frances mentioned it in the comments of an earlier video. FiraCode has programming ligatures, which you can see in the channel symbol (
Thank you for the great videos. This is really helpful.
What editor are you using?
He is using Visual Studio Code [code.visualstudio.com/] with the Go plugin [code.visualstudio.com/docs/languages/go]
Thanks Very clear explanation.
Hi, amazing stuff! I was still struggling on how to use context skimming the official docs. However this is simply awesome. Especially thanks for showing that you can't send context values across network.That would be stupid idea anyway :-)
Deep dive in context ...id be glad
Hey Francesco, huge thanks for your series of videos. was wondering if you can post the code repo on github
+Anh Nguyen it's on GitHub.com/campoy/justforfunc
Thank you for this video.
This was super helpful, thank you.
This was great, thanks so much!
Just one word, Awesome
thanks Thor.I now understand Go better
That was very useful, thanks!
amazing video , thank you!
useing a function (sllepAndTalk) you created for half of the video ,and not showing how that function worked was a waste of my time.
thank you for frustrating me back to the doc.
excellent explanation
Who's here from the Aug 20th Go Time podcast?
BTW at 21:00 - since go1.13 - you can now do this in one call with: golang.org/pkg/net/http/#NewRequestWithContext
I really, really, really would like to see complete series about how to create IDIOMATIC Client Server WEB application with most common CRUD operations using gRPC and MySQL. Client and Server should be just simple Go programs. Would like to see: IDIOMATIC Directory/File organization in context of github.com/myusername/. gRPC service interface, and message/+field idiomatic naming and organizing into packages. Package +nested package importing. Compiling nested .proto's. TLS secured gRPC communication. Idiomatic endpoint URL constructions. Context. Displaying in browser - single record, list of records, single record + list. Submitting form, updating record, creating nested records - like, when customer is created, also some log record in the same DB is created pointing to the same customer (tx). And so on so on.
Basically, EVERY beginner want to see complete IDIOMATIC example of writing production ready basic DD web-page.
Nobody is teaching this. 98% of tutorials and books teaching the easiest way - Just mess everything into main.go and use mock data! This is total BS! This is not how good things should be teached.
It is much better when you see, how great foundation looks like and then starting to tweak, and to learn all those used patterns in details. When you have no context in head, it is impossible to learn right way. Iterating thru the trial & fail is way to learn for sure, but it is not the most effective! It just wastes too much human time.
YES - this kind of tutorial will take time to record. But this will be the SINGLE PERFECT TUTORIAL in the whole f*g WEB.
Very Nice! Thatk you Francesc!
very helpful, thanks very much
Very helpful. Thanks.
this is so good.
super awesome!
Great video francesca ;)
That's not my name
JustForFunc: Programming in Go hehe 😁
JustForFunc: Programming in Go i know, i just couldnt remember which video it was where at the end someone couldnt say your name :)
That poor plant in the background needs water
Can you please make a video on Interceptors. :)
Sure ... what do you mean by interceptor?
@@JustForFunc They are like middlewares. It does come with the standard grpc package.
github.com/grpc/grpc-go/blob/master/interceptor.go. The standard package has a big limitation. Middleware/Interceptor Chaining is not allowed.
There are third party packages to accommodate chaining. This one is pretty popular --> github.com/grpc-ecosystem/go-grpc-middleware
The concept looks very simple but it might get a little confusing when you dive deep into it. Would be helpful if you make a video. Thank you :)
Oh so you mean grpc interceptors specifically!
@@JustForFunc Exactly. I understand there are quite a few documents (should I say incomplete documents) on the internet where people keep comparing interceptors to middlewares, explain the differences between the standard grpc interceptors and go-grpc-middleware but do not go into the details. For someone who already know the basics of grpc, interceptors in grpc is a great way to advance his/her knowledge. The way you explain things is priceless, so thought of requesting you to do a video on it :-).