The Most Efficient Struct Configuration Pattern For Golang

[@anthonygg_]

► Join my Discord community for free education 👉 discord.com/invite/bDy8t4b3Rz ► Pre order (get 30% off) my Golang course 👉 fulltimegodev.com Thanks for watching

[@kafran]

This pattern is commonly known as the "Functional Options" pattern. The Functional Options pattern is a design pattern in Go where you pass in functions that alter the state of a type. These functions are often called "option functions". They provide a way to cleanly design APIs and offer a more flexible and readable way to interact with a function or type. Nice demonstration on how to implement them. Thanks.

[@jeezusjr]

Perfect timing! I am doing something right now that can use this pattern. Thanks!

[@necroowl3953]

1. Make the config elements private 2. Make the options type a public interface, with a single private method (apply(config) config) 3. Expose public functions returning this interface 4. Add a function type that complies with the option interface, make that type implement the apply method by calling itself. 5. Add a no-op type for validation when needed. 6. Validate input before returning a config type. Boom, functional options with a restrictive builder pattern, for your constructors. You can make it generic too.

[@macot79]

Hey! Those suggestions are really great, I'm new at Golang and have tried to adapt Anthonygg's example with your suggestions, but I'm a bit stuck at step 5. Could you clarify what you mean? Thanks

[@hugorojasmonzon1487]

Could you create a github example of these ideas ?

[@abiiranathan]

Functional Options Pattern... popularized by Dave Cheney

[@wuilliam321]

Any book/reference? Thanks

[@jamesprendergast7158]

Surprised gg didn't know the name TBH

[@Cruzylife]

@@jamesprendergast7158 because Ant creates his own meta

[@TehKarmalizer]

Looks like functional riff on the builder pattern.

[@Kiran_C_Nayak]

Dave Cheney's Talk: kzbin.info/www/bejne/aGXPd6d9fbyrd7M Link to Rob Pike's Blog mentioned in Dave's talk: commandcenter.blogspot.com/2014/01/self-referential-functions-and-design.html

[@jex8885]

This channel is amazing, you're making my Go code better and better for every video!

[@banatibor83]

It looks fancy but a bit of a hassle. A simple builder pattern is much more readable I think. The default values are nice. Then just put methods onto the ServerOpts type which return *ServerOpts. type ServerOpts struct {...}, func NewServerOpts() *ServerOpts {...set defaults...} , func (s *ServerOpts) Id(id string) *ServerOpts {... set id ..}, func (s *ServerOpts) MaxConn(maxconn int) *ServerOpts {...set maxcon..} Then you can use it like this: s := NewServer(NewServerOpts().Id("my-server").MaxConn(100))

[@Ascentyon]

Exactly. This is much better for discoverability, instead of having a bunch of standalone functions.

[@matthewwagner5396]

Feels like you don’t even need the opts struct here. Just use the server struct itself

[@jaiswalrohan]

@@matthewwagner5396 yep

[@arieheinrich3457]

Thanks for diving into design patterns Anthony ! This is what separate starting devs to more advanced ones, that we all aspire to be, and that is understanding design patterns. Looks more like the Builder pattern than the Visitor one.

[@anthonygg_]

Apperantly is the “functional options” pattern 🤷‍♀️

[@arieheinrich3457]

@@anthonygg_ yes Functional Options Builder pattern !

[@dejanranisavljevic]

I also know this as a builder pattern, it's very common and good use for building test fixtures

[@yogeshdharya3857]

3:50 to 3:53 Witch Craft and Woo Doo ! . My man's a part-time wizard

[@vitiok78]

Reinventing the wheel of named function parameters with default values))

[@susiebaka3388]

you're free to use a map or whatever my guy

[@bigtymer4862]

Love these pattern videos man!!

[@adriancmiranda]

It's a very good pattern, thx for sharing. Your didatic is very good!

[@kylestubblefield3404]

This is a great video. I stumbled onto using this pattern by accident, it was very useful for a previous project I was working on

[@skyline7349]

Thank you for posting this Anthony, very nice pattern and will be trying to incorporate it with my starter projects

[@Programscape]

Watch this video for some time ago, remember. And return now to implement this in my project)) Antony is gigachad, thx for the video

[@lokthar6314]

Quality Content

[@anthonygg_]

🙏

[@lotfikamel5947]

As always very advanced content

[@bjugdbjk]

Just love this man !! More like this brother, these r the stuff which really play with the Dopamine !!

[@rajdama205]

The way you make any concept understand is just amazing !!

[@kajfehlhaber]

Awesome video as always! ❤

[@whatwhat2573]

Nice clean pattern to understand too

[@vitaliik8315]

Thanks for yours lessons. One of the best video lessons for go.

[@JT-mr3db]

Does feel like a take on the builder pattern. Incredibly handy pattern a lot of Elm libs use as well.

[@joshuatye1027]

Builder pattern returns this though. This accepts an unknown number of functions that may or not even return valid struct keys.

[@codewithluke]

Nice one. Really enjoy this pattern.

[@kanfit]

Thanks, I think you also talked about a bit of functional programming in Golang in this video, which is very nice.

[@grim.reaper]

This is amazing and used in a lot of places tbh. This is very true that it's used in gRPC, also ssh package if I am not wrong because ssh connection has a lot of options. While putting this in a library the "withXYZ" functions can also be a method where it can have the server receiver methods. This is so so so amazing!!!

[@Rohinthas]

Aah functional stuff is just so pleasing to think about

[@Crazyfulization]

Really helpful, you can see the benefit right away! Awesome stuff

[@matthewbridges3147]

Thanks for the explainer, I'd have been searching docs for a standard way to do this without realising it requires a pattern. In JS I'd just use a default arg param and a spread operator to override

[@hugorojasmonzon1487]

Amazing video, thanks for sharing your knowledge!

[@victorkochkarev2576]

This is a beautiful pattern!

[@michael_loc009]

I wish you would upload this amazing tutorial when I first learnt Go.

[@henrisetiawan7547]

Gem....amazing explanation..and going sub ..

[@sibonelongobese8639]

Top notch stuff 👌🏽

[@grise123]

nice pattern, seems very helful

[@howesteve]

Congrats, you just converted your one liner function into a 50 lines api, introducing lot of nested function calls and even loop overhead, by using the old builder pattern.

[@anthonygg_]

Well, you are not wrong.

[@burionyt]

only real world shit in the channel 💪🏼 love your content as always ❤

[@fluctura]

Meanwhile in TypeScript: mergedOpts = { ...defaultOpts, ...opts } as Opts But its a cool pattern. Go doesn't have "map spread operator" and thats a good thing probably. But sometimes it would be so handy to have more syntactic sugar

[@fluctura]

btw it is a mix of Higher order Functions you write and you use them to compose a struct using Inversion of Control. So basically Higher order compositional Inversion of Control based state management (as your config acts as a state) 😂😅

[@pserra94]

Hi Antonio, how are you? I'm migrating from nodejs to Golang thanks to you and your videos, always amazing! I don't know if it's asking too much, but could you make a video/tutorial for developing web crawlers with golang, please? I was googling about it but I didn't find any good content about it. Thank you so much my friend, you are amazing!

[@fauzi5848]

This is so useful, thank you so much!

[@miguelborges7913]

This is great!

[@TuvaluHODL]

Opts (Opts, opts), opts Opts Opts opts😅 Thank you Op for the video ; I appreciate your talent and time

[@quantenlicht]

Start: 1:03

[@johnb7657]

Thank you, perfect

[@orterves]

That's a beautiful pattern

[@vanshajdhar9223]

Beautiful ❤️

[@mihaiii6720]

This pattern is so good !!! I guess you can use it in TS/JS too

[@fringefringe7282]

This is pretty cool.

[@ShadwTrooper]

Clever. I like it.

[@Epistemer]

This is honestly really cool, I always hated how there is no way to do kwargs in go

[@GustavoFSx]

Beautiful

[@jf3518]

Great work around. Though I would not use it, as I cannot use an existing config to initialize the state. Instead I would just use merge function to join default config with provided config.

[@inaccessiblecardinal9352]

Good stuff. Aws' sdk has this pattern in every client (that I've used).

[@kevinkkirimii]

I have misused this pattern. Quite useful

[@seanknowles9985]

Hey big boss, two questions: 1. How to make an efficient cron job scheduler from scratch? 2. How to make realtime subscriptions to database values - for example we have key value store but then we build realtime subs that can subscribe to changes of a key and its data? Another quality video for the fans homie, love this channel. Bests, Super fan.

[@reikooters]

Isn't this kind of a limitation on the language? If you could specify default values when you declare structs, then this would go from 50 lines down to 10? You mentioned doing this function approach if you were building a library. How would you do this in a way that's easy for consumers of the library to use and know which functions are available to be used for configuration? Would you put them together into a "configuration" package? (I'm not a Go user, just interested)

[@sunofabeach9424]

this language is limited is so many ways that eventually you give up on it and probably on life as well. GO, while being a higher level than C, looks and feels as clunky as C. but what in C is honestly called a hack, in GO called a pattern. C was designed to be as easy to parse and compile as possible and that's why it lacks so much. GO has no such excuse

[@klamberext]

The example here is for overriding defaults. Imagine instead a environment specific factory configuration or just a variety of options: Lets say your server/thingy supports different storage services - S3, ftp, local. Now you want to say: withStorageDriverFromEnv, or withFtpStorage or withS3 storage. All of them require different kinds of paths, credentials etc.. Now do that with default values on struct. The limit is in the example given.

[@klamberext]

For consumers you provide docs. Or you instead implement the OptFunc as an interface . Then it would be possible to view the list of implementations for given interface(if you have good IDE) .

[@botyironcastle]

with golang you always have to reinvent the wheel, this is called required and optional params with default values, and a good language has it out of the box without defining 200 functions and polluting the code space and destroying readability.

[@jaiswalrohan]

yep, as someone coming from python i am like ＼（〇_ｏ）／

[@adyanto4043]

can we use builder design pattern for the same?

[@Md.MitunRahman]

this is unbelievable

[@PouriyaJamshidi]

This was really informative. A side question. Any particular reason for using int instead of uint in maxConn? I noticed most people use int where a uint makes more sense. In this case, we cannot have negative maxConn.

[@anthonygg_]

Just for demonstration purposes. Uint is better.

[@PouriyaJamshidi]

@@anthonygg_ Thanks. I think somewhere I heard something along the lines of integer underflow and was wondering if this has something to do with that

[@helmchen1239]

-1 meaning unlimited could be an option in that case though :)

[@myrachanto]

that was really cool trick i like it

[@ChristopheHa]

I guess this could also be combined with builder pattern, and then you can just can chain those withX on the builder and build will return the instance

[@MrXperx]

Looks to be a variation of the builder pattern. (I come from OOPS)

[@matiasbpg]

What is the advantage of this pattern over a builder pattern?

[@sfsdeniso5941]

Error handling In go you cannot chain builder calls as each must return error (and not this)

[@matiasbpg]

@@sfsdeniso5941 thanks for the answer! However I think a builder for the opts struct shouldnt have this problem, but now I can see the inconvenience. Maybe a walk around could be that the builder struct could itself carry through the error as a property and the build method could return the value error tuple

[@CaffeineForCode]

The only problem with this pattern is that you lose info from the LSP. Working with the AWS SDK, I often have no idea what is possible or what the opt functions do without reading the documentation. It’s a trade off, especially when you have a lot of config options

[@tigranrostomyan9231]

I think it is possible to solve by putting all 'OptFunc's into another (child) package, e.g. "server/opts". Maybe it's a bit of overkill but if you then type 'opts.' and call autocompletion it will list all 'OptFunc's

[@jub0bs]

You write: "I often have no idea what is possible or what the opt functions do without reading the documentation." But is a classic config struct any better, in this respect?

[@jurijskobecs2803]

@@jub0bs of course its better, you got one place/struct to check all the possible options

[@jub0bs]

@@jurijskobecs2803 The fields of a struct type tell you close to nothing about how they're going to be used by the rest of the program. Their names give you clues at best, and their documentation is meant to give you accurate information. But you'll need to dig into the implementation to definitely find out. In this respect, a struct isn't superior or inferior to functional options.

[@HiperCode10100]

very good thx bro

[@plashless3406]

amazing.

[@luizfernandopereira5120]

This pattern is just an adptation from the Fluent Interface Pattern existing in OOP languages, is nice to see it in go though.

[@MesheeKnight]

We use to call this the Option pattern. Would you have a nice one for Mandatory config where you cannot provide a reasonable default, like a sql.Conn?

[@anthonygg_]

Thats an amazing question! You could force an interface as option and implement a noop for that interface as default to prevent nil pointers. What do you think?

[@MesheeKnight]

@@anthonygg_ i see the Idea, but i am looking for a way for large amount of mandatories, noop wont do the trick i think

[@sfsdeniso5941]

It is called 'Functional options pattern' should look like this: func NewServer(addr string, opts ...Option) error () {.....} so here addr is mandatory. Usage example: server, err := NewServer("localhost", withPort(8080), withTimeout(time.Second))

[@MENTOKz]

oh snap cool man

[@heartly4u]

why not create a builder pattern, which will do the same as what you are doing, with more readability.

[@JohnDoe-ji1zv]

Can you share example how your pattern is more clear than the one shown in a video ?

[@heartly4u]

@@JohnDoe-ji1zv wouldnt it be more readable this way newServer().withTls().withId().withMaxConnections().build()

[@tgraupne]

I was thinking about the same thing. 🤔 Maybe the authors or some other people would like to chime in.

[@TheSurvivor1963]

This is a good pattern, I've been using it for years, but why not make an option function that returns the same option function with the previous value? That way you can change and reset options on the fly. An example could be to elevate debug logging temporarily for some very complex code segment. Rob Pike wrote an article about this for some years ago. type Option func(*Some) Option type Some struct{ ... dLevel int } func Debug(d int) Option { return func(s *Some) Option { t := s.dLevel s.dLevel = d return SetOption(t) } }

[@startengine8838]

how inner function (the one that you retuen in options functions) gets the pointer which it has as input when higher lexical scope doesnt provide it

[@infastin3795]

I hate functional options pattern. It just so much worse compared to just passing a pointer to a structure with options.

[@pyronb]

Can somone please rephrase what's happening at 6:15 with fn(&o) ? It's not clear to me how everything works together

[@ja31ya]

He's using the spread operator to allow as many OptFunc's as you want. He then uses the range operator to loop through each OptFunc and executes them with a reference to the options struct (that's the **fn(&o)**), so that the OptFunc can modify the options directly, overwriting the default options.

[@folium5725]

Hi Anthony, what theme do you use?

[@anthonygg_]

Gruvbox

[@suikast420]

Cool fancy< stuff. What about toi make a fluent api with that style?

[@ivanrachev9409]

Cool approach! Just wondering, why did you go back to VS Code?

[@timurgirfanov531]

It's like Visitor pattern, but in a functional way

[@sfsdeniso5941]

It is called 'Functional options pattern'

[@1_PieceOfCode]

why not just set default conf at first and then use factory pattern so user can just change config as he wants?

[@yawneed]

Hello. Where does download your vscode config?

[@maninalift]

Is there an advantage over the builder pattern? It seems to be equivalent in usage but I'd guess harder to optimise.

[@x0z59]

will this thing not make established Go features convoluted? aren't you not reinventing the wheel here?

[@mozhago8280]

Is this pattern used in go starndard lib?

[@dmitriyobidin6049]

The only problem i have with this pattern is that it is not obvious which methods/func you can use as options.

[@metaltyphoon]

AWS SDK uses this pattern too.

[@vasiliyaristov7148]

Interesting

[@igor-glagola]

Looks like some sort of builder pattern

[@robinlioret7998]

I think it's a Go version of the Builder pattern, but not sure.

[@jungervin8765]

Why not just create a default struct every time you want to use this. Create a default func, and the user can change the options. How is all that "with" functions not polluting the function names?

[@polnio]

This pattern looks a lot like the builder pattern. Am I wrong?

[@chaitany.a]

This is like a functional builder pattern...?

[@faiz_0000]

damn, so much work for just an optional config parameters can't you just make every args optional and assign default value to it if its nil?

[@AmedMoore]

This pattern is called “over engineering”

[@henryconner780]

You do be the that guy

[@caiocesarmelolopes2156]

That looks like function as parameter that was introduced in java 8 with lambdas xD

[@TimurSevimli]

Why not just take configuration data from a JSON file, like config.json?

[@5packsabs]

How to code??

[@anthonygg_]

Press buttons

[@TheMereth]

damn so much work just to have required/optional parameters