The Illusion of Stable APIs

00:00:05.420 so for our last talk he's the creator of trail brain brazier

00:00:13.340 that's correct Trailbreaker a

00:00:18.580 high-level weber she textured solution for ruby apps

00:00:25.660 you are not the only one that wants to sleep he also wrote a book about it on

00:00:31.519 lean PAP you might have noticed him yesterday

00:00:36.950 being the soul of the party he's the least German German I've ever known and

00:00:42.079 I've been living in Germany for two years now three years yeah Munich

00:00:47.559 so yeah it's Munich you know there's a lot of Bavarians there so please welcome

00:00:54.980 on stage mr. Nick Souta three years come on

00:01:09.220 better

00:01:15.009 it's always big pleasure - and a two-day conference

00:01:22.640 and to sit all day in a dark corner trying to cure your hangover because the

00:01:31.060 after-party is on the first night and not on the second night

00:01:36.430 actually I think this is a bad excuse from the organisers

00:01:41.780 so they told me everyone is leaving today who is leaving today

00:01:48.009 it's like five people okay I'm sorry I mean I'm happy so you

00:01:55.060 could actually party last night and I think you partied hard because you didn't have to give their closing

00:02:00.520 presentation on the second day and so on and so on and so on but I also hear rumors about and you know official after

00:02:08.860 party tonight so maybe you want to rebook your flight and stay for a couple

00:02:13.959 of more days hey Rafael take a seat okay to

00:02:20.100 make this to make this might be confusion my name is actually

00:02:26.680 not are my name is Nick I'm also not from

00:02:32.730 Bulgaria I'm from Germany this does not mean I cannot drink as much luck here as

00:02:39.580 you guys can drink so I'm it's a it's a bit said he this lovely guy actually I

00:02:45.940 never know how to pronounce his name I love him to the bottom of my heart we've been partying at many conferences and

00:02:52.540 having deep and profound debates poor Tschida is that her because if you

00:02:58.120 know someone for like a couple of years and it's summer you say like hey it was nice the last three years with you but how do I actually pronounce your name

00:03:04.570 it's a bit awkward so anyway he's um usually a party animal and I'm nothing

00:03:10.390 compared to him he parties like like like a maniac unfortunately he is a bit sick today

00:03:18.230 oh also yesterday he is I think he's in hospital it's like not the coolest thing

00:03:25.459 to do on the weekend but on the other hand it's a cool story like I said hey how was Friday Oh

00:03:30.970 appendix or surgery nothing special cool okay so I think we should send him some

00:03:37.879 message and like maybe we can all yeah all yell into the camera I don't know

00:03:43.459 something like we miss you or something that's

00:03:48.860 I'll count to three and we all yell this yeah so you can also wake up again so

00:03:53.930 one two three uh we miss you ma ma ma

00:04:08.530 we don't have time for applause I have so much content and only 40 minutes

00:04:13.600 so when I when I when I when I wrote this presentation 17 years ago I

00:04:20.799 titled it the end of rails question mark very controversial aggressive title

00:04:27.860 people said hey man dick you're such an you're always talking about rails and you really like aggressive and

00:04:34.070 you're not contributing enough to be so like weird and

00:04:40.000 so yeah I agreed I am a little bit of an ass so I am renamed it to the illusion

00:04:47.660 of stable api's and the great thing about this is I this

00:04:57.230 could be anything this talk and it is some random stuff and but the problem

00:05:02.510 was people started asked me so actually what's your talk about and like it's a cool title but what is it about and I

00:05:10.570 could not I did not manage to summarize my talk without saying rails and something- so I

00:05:19.400 decided to completely rewrite my talk talking about the real stuff now

00:05:26.080 also I want to be functional functional hipster just giving you a little bit Joe sorry so and what I learn about

00:05:32.330 them rakia is it's a pretty strong it's good to heal and inflammations it makes

00:05:39.140 people tweet weird photos in the weirdest hours of the day with

00:05:44.660 toothbrushes not with cats it's a bit different and it does not make you blind

00:05:49.729 that's a rumor that's not true right Raphael can you still see me yeah

00:05:55.340 yeah yeah and what's also awesome awesome

00:06:02.000 about him rakia is you I don't know I I don't get hangover from it so I could

00:06:07.130 actually manage to party yesterday on the first night of the conference by the way not the second before I give my

00:06:13.700 closing talk and so on and I could actually I managed to go and see the first talk I mean I I woke up at like

00:06:21.670 9:00 or something and managed to take a selfies to prove you that I was in just

00:06:26.770 as amazing elixir talk every time I hear just so you talk about elixir I want to

00:06:33.430 stop using Ruby and start using elixir but now this is really conference okay enough

00:06:40.380 let's talk about AP ice many people in this room I not exactly think

00:06:47.650 that I'm gonna talk about document api's yeah how cool JSON documents and yeah

00:06:53.590 and rails API and activemodel so you realize absolutely no I'm going to talk

00:07:00.010 about AP ice as in what we use as programmers yeah as a programmer you use

00:07:05.770 api's on a daily basis you create ap is when you write code okay so I'm not

00:07:12.310 going to talk about awesome JSON documents I'm gonna talk about and stuff like

00:07:18.270 constants can be part of an API or methods can be part of an API and the

00:07:23.650 signature of are you applauding me that's really nice and the the signature

00:07:29.710 of the method arguments is part of the API on API can also be the structure of

00:07:35.560 objects of functions and the workflows you use so that's all parts of an of an API and the cool thing about ap ice is

00:07:43.090 that they make my life your life not clapping anymore and all of your lives

00:07:50.100 excellent because we can use stuff other people wrote or we can write stuff for

00:07:55.870 other people and we don't have to really understand what some what's happening inside it's pretty cool

00:08:02.230 like you you just I don't know like it's a bit like the power plaque you have like you know internally it looks like

00:08:08.169 this I have no idea I mean I had physics in school and I don't know there's like voltage and something else and something

00:08:14.800 kills you and something does not kill you and on so on it's it doesn't matter I just use my power plug plug it into

00:08:21.100 the socket then I have power and can recharge my iphone that I not have and

00:08:27.780 so what API is basically offer us are it's an abstraction

00:08:33.029 extracts away internal knowledge you need or you maybe you don't even have

00:08:39.219 from your task so api's are attractions that help programmers and people who

00:08:46.180 need to charge their iPhone because you have to charge our phones five times a day apparently and you don't need to

00:08:52.120 have knowledge about the internals and the cool thing about api's is they help

00:08:58.330 but what's even cooler is when people start to extend api's and realize hey

00:09:03.750 this is kind of cool what I'm what I've done but actually I would love to add

00:09:09.300 functionality on top of that for example it's a stupid example of it it's like

00:09:14.380 this is my talk so there's lots of stupid examples and a login form is kind of an abstraction for authentication

00:09:20.740 yeah you authenticate yourself this is my username this is my password and at some point people said I

00:09:26.760 had too much rakia in my life I always forget my password so let's allow

00:09:32.110 logging in with Facebook or github because every person on this planet has github apparently and so people started

00:09:39.790 to add buttons to log in false way just say lock me in as my github whatever

00:09:45.220 handle and then you don't have to remember your password so an excellent example of how api's can be extended

00:09:51.970 when it makes sense to extend them yeah so an API doesn't mean it has to stay

00:09:57.520 like that for the rest of the of the time of this piece of software and it ap is are meant to be changed when it makes

00:10:05.080 sense this is my favorite part of the talking

00:10:11.370 Ruby on Rails so and API scum in gems an API is come

00:10:19.450 in form of Ruby Ruby internals and all this kind of

00:10:24.730 stuff API also come in form of for example the rails framework yes now you have to say oh no it's he's

00:10:32.440 gonna talk about res no not again so rails has this has a lot of like peppers

00:10:38.410 and you know the way active record works and all this kind of stuff but one part of rails API is the so called they call

00:10:44.920 it MVC yeah so the MVC pattern is basically the architectural abstraction

00:10:53.230 to help you write web applications and it's a bit like I don't know really how it's supposed to work like the

00:10:59.410 controller now is about the view and the view who gets rendered by the controller and the model can be presented via the

00:11:06.280 controller to the view and all this kind of stuff and and in in rails late they make it like super sweet like I mean

00:11:13.060 look

00:11:24.970 simple and okay it's so easy to write applications because you have

00:11:31.050 and it's really only a few steps to to to get

00:11:37.200 application running so that's this is like a typical flowchart you don't have to understand it and so it's like you

00:11:43.180 the controller assigned some variables that it gets from the model layer from the suite active record with glasses and

00:11:49.960 then it sends those data that data to the view and so on and so and so on and

00:11:55.170 again it's really like tiny and sweet and it works it's great it's fantastic

00:12:01.450 people can learn how to write applications within I would say

00:12:07.020 10 minutes yeah so you can I've done I've given a lot of lectures at rail

00:12:13.540 skills and it's fascinating to see people who have never written any code write a dynamic page in literally like

00:12:22.780 an hour but the problem is that

00:12:27.870 we have this MVC parent and we think it is perfect stop stop reading this

00:12:34.350 because we have the so called rails doctrine written by DHH himself a

00:12:40.900 fantastic guy the register train basically says MVC the way we do it or

00:12:46.990 else and you all do MVC because we have a doctrine is the way we write software

00:12:52.620 ok our abstractions our API is perfect and we write applications using

00:12:59.840 we see because the doctrine nope and some people disagree including me if you

00:13:07.280 couldn't tell and yeah for example there's a mic program

00:13:13.930 where he basically figures out okay some ruie developers don't even realize they

00:13:19.430 are writing Ruby they think they're writing rails and it takes a couple of years for them to realize rails is only

00:13:24.800 Ruby because because rails the doctrine make it really makes it really hard to

00:13:30.590 understand where are my where are the boundaries of the language to the framework and

00:13:35.890 are there many are there may be more layers I could use in my application instead of MVC only so

00:13:43.450 because the problem is that we all use this beautiful MVC pattern and we end up

00:13:49.220 with really really really convoluted code I

00:13:54.430 don't want to say messy because messy would be negative and then in the end of the talk everyone will say you are so

00:13:59.810 negative so we have what is this this is a view for examples of the views in rails if

00:14:05.360 you use the standard embrace tree you will have really big views with like a lots of authentication authorization

00:14:12.020 logic helpers rendering ten partials in a row passing down locals using instance

00:14:18.980 variables from the controller that you might change on the way and this kind of stuff so it's super hard to write

00:14:24.140 complex applications and complex views in in rails and the same is with what's

00:14:30.020 that that's a controller the same happens in the controller because we only have MVC so you have authentication

00:14:36.380 logic or authorization polymorphic dispatchers you use the

00:14:42.020 persistence layer in every different position of this of this code and you pass stuff you

00:14:50.450 change the incoming parameters you validate stuff you trigger callbacks but you it's like it's super hard to follow

00:14:57.350 what a rails developer actually does in a rails in a controller action and the

00:15:03.200 same in the model I mean it's like some people might think yeah you're a bad

00:15:08.480 programmer you you don't know how to program and it's true I have no idea how to program but there is lots of smart people out there

00:15:15.660 and they still run into this problem like we have massive models and then you know again there is like state machines

00:15:22.080 and validations and callback logic and colleagues getting triggered when you don't want them and validations being

00:15:27.150 run when you don't want them running this kind of stuff and this is not the

00:15:32.310 problem of because we are stupid I mean I'm stupid but you're not and so it in what I'm trying to say is if

00:15:41.390 you realize my abstractions are not enough anymore you have to change your

00:15:49.890 abstractions yeah your API is this is the job of a good software developer and

00:15:56.300 I do not understand why rails is so slow

00:16:02.910 in accepting that its obsession with MVC is

00:16:07.970 taking us into the wrong direction in my opinion if you like massive controllers

00:16:13.380 massive views and massive models okay and so I want to show you an example why why

00:16:22.320 this is hard to deal with and how you can easily easily change this with

00:16:28.890 additional abstraction layers okay so we all love active record I actually love

00:16:34.260 active record without certain features who does not like active record

00:16:42.020 doctrine so a typical thing to do is you have user

00:16:49.290 model and you have validations like my the name can be only twenty characters the email has to be email format H has

00:16:55.800 to be numerical so when I use user to create and a pass in some rubbish Stata

00:17:01.140 for example the name is the right boom the validation says hey sup that's not cool and that's great too to make sure

00:17:07.770 that the data the incoming data is saying that's a great feature the problem is now when I am let's say I

00:17:16.530 want to create a user when I'm as an admin user yeah I'm the admin and I want to create a user and I want to bypass

00:17:23.760 certain validations for example as an then I want to create a user and be able to give that user a name that is longer

00:17:30.650 than 20 characters just because I'm an admin I'm cool by the way what about my head

00:17:40.659 so I want to I want to create a user with a longer name than twenty characters as an admin only isn't open

00:17:46.100 the normal user should always have this validation so what I actually want is the same as before there's a normal user

00:17:52.640 without the first validation and in rails this is basically impossible

00:17:57.650 because because we focus on push pushing all the

00:18:03.500 validations into the model yeah so what they did is okay this is a missing feature let's add if else to Kent so you

00:18:10.850 can like turn often on validations depending on the context because we don't want to change our architecture we

00:18:16.820 don't want to change the API we want to keep the model have all the validations yeah so if Sun else started to pop up in

00:18:23.510 the model and I mean do we like if some else we do not like if something else in

00:18:28.730 our code really we like polymorphic code because it gets super hard to read and follow what is going on yes every time

00:18:35.299 you add if-then-else into especially in a declarative DSL or API you are

00:18:41.240 probably doing something wrong structurally but it's always easier to add something instead of changing stuff

00:18:47.630 structurally rant over so the problem is that we try to M that

00:18:55.190 we try to handle two different contexts in one class yeah we want both different

00:19:00.620 sets of validations in the user class and I know that we have the validation

00:19:06.650 context feature in rails but I also know that no one is using it so the problem

00:19:12.950 in in in in this example is two contexts creating a user as a normal user creating user as an admin are handled in

00:19:21.140 one class because we want those two contracts in one class because classes

00:19:26.179 are bad and they yeah i'm alexi oh now I know Ruby

00:19:33.460 the way this is handled in other frameworks is surprisingly simple for example who has

00:19:41.570 heard of elixir and Phoenix Phoenix is a fantastic framework it's

00:19:48.770 getting better by the day so the way Phoenix handles this is a very very

00:19:54.020 fascinating so I mean this is a lot of code don't flip don't don't go nuts this

00:19:59.570 is only we this doesn't even matter what the code exactly does but what they do is they have them

00:20:06.340 modules just say what's the exact name of this asset

00:20:15.400 modules functions whatever so in this function yeah that is that is

00:20:26.420 fields in a so called schema and then they have a change set and this change

00:20:32.480 set contains validations and typecasting and other features I'm going

00:20:38.600 to talk about in a second her context yeah so in Phoenix instead of having the

00:20:45.110 code to create a user as a normal user and there's an admin in one class or in

00:20:51.020 one function in Phoenix you can't simply have two functions and there's two functions can share validations those

00:20:57.320 two functions can use different type castings whatever and those validations there's two those two functions or

00:21:06.050 modules can be used depending on the context when I'm logged in as an admin

00:21:11.240 I'm gonna use a different function and it is surprisingly simple how they solve

00:21:18.140 this problem of I want to have two different sets of validations on four different contexts

00:21:24.970 in a relatively young framework for Ruby

00:21:30.070 hey we like Ruby right whoa I

00:21:35.170 know it's really late and everyone wants to go to the in official alpha party me

00:21:40.309 included so Trevor is a framework that works on

00:21:46.490 top of existing frameworks like hanami rails a grape Rhoda and basically brings

00:21:54.020 what we call high-level architecture into into Ruby software development

00:21:59.120 because I said we already know that I'm the author of the of it so it's a shameless plug in Trevor is that this is

00:22:05.180 basically identical to the way it works in Phoenix and we did not copy stuff from each other it's just common sense

00:22:11.390 an object-oriented or in in functional programming yeah so again

00:22:19.400 don't freak out this is only a structural code you don't have to understand all the implications in

00:22:25.490 Trezza you have what we call operation which is a class per context so I have

00:22:30.530 an operation to create a user as a normal user and I have an operation to create a user as an admin and what we

00:22:38.120 have in trailblazer is contracts so in a contract operation you define the incoming fields

00:22:45.260 exactly the way Phoenix does it and you define the validations per context so if

00:22:50.930 I want to remove validations I add a new operation with a new contract and I can

00:22:57.260 then use this validation in my operation so the runtime code is not really relevant at this time but the the point

00:23:04.340 here is exactly the same we had before yeah instead of trying to push

00:23:10.330 everything into one class just because we want to keep MVC like we can't change

00:23:18.220 instead of pushing this into one class we have two different operations they can share validations they can share

00:23:23.920 typecasting and all this kind of stuff coercion features you will always be dry but you don't have this problem of ah I

00:23:31.670 don't want this part of the code run when the context is like this you just have two different objects for two

00:23:36.860 different contexts it's really simple it's like why would I bother to push everything into one class and then

00:23:43.420 disabled afterwards instead of just having two separate classes to handle two different things so we

00:23:49.990 we what we do or what many people do is they rethink their ap is because they

00:23:56.570 realized hey pushing everything into one class for example doesn't make sense let's do something else and

00:24:03.550 it's it is actually not that hard and I don't know what's the with having two

00:24:08.899 glasses instead of one some people think oh wait are you crazy glasses object

00:24:15.039 if you use object it's gonna be slower because my garbage collection and what

00:24:21.429 objects to do one thing only and 15 things at once that's like what's wrong with you and then relax relax it's

00:24:29.179 really simple just yeah relax so using objects is not expensive because every

00:24:36.139 time you use a string or a symbol or a hash or you do an hash merge an object

00:24:41.990 is created as well so it doesn't matter if you create a hash or if you create an operation to create a user it is really

00:24:50.090 cheap in Ruby and that's because we have really smart people working on their kind of stuff well he's not paying attention

00:24:57.190 another example of this obsession of we have to have everything in one class

00:25:02.929 because is the old feature it's gone now am etter

00:25:08.899 accessible so etter accessible I don't know if I have an example yes accessible

00:25:14.090 allowed you to define if I create a user I only want to

00:25:20.330 respect name email in age everything else that is coming in should be ignored

00:25:25.700 okay so it's basically not a validation it's more like a filter and again it was

00:25:32.269 like where do we put this into the model of course because fed models can you control it so we could say if I create a

00:25:39.590 user just ignore everything but name email and age but only when you're a normal

00:25:45.950 user when I'm an admin I want to have all kinds of fields allowed because I'm

00:25:52.159 an admin how does this work in rails it is impossible again

00:25:57.639 isn't it so what they did and that was actually the right thing to do yes I can

00:26:04.789 also talk positively about good stuff but okay stuff they introduced strong

00:26:09.860 parameters at some point because they figured out hey we cannot handle two contexts with one declaration in one

00:26:15.980 model we should have one declaration per context and then they introduced strong

00:26:21.049 parameters written by our doctrine writer and

00:26:26.390 highly inspiring individual David Hansen so that was a good thing because now you

00:26:32.490 can have access control or the filtering as I called it per context um

00:26:38.510 the problem was well is that this code sits in the controller so now what

00:26:46.110 happens is you have some validation code and some filtering code in your model and your

00:26:53.310 some validation code and filtering code for example strong parameters in the controller and again I do not understand

00:27:00.270 what is the problem to just introduce a third layer validation for example that contains both parts because it's both

00:27:07.230 validation relevant and that is again exactly what Phoenix and Trevor is a do

00:27:12.480 okay look at this beautiful logo take a deep breath

00:27:18.740 here we go so in this function or whatever we called it module I'm to say

00:27:25.890 it's apparently not here I'm really really really angry so it's a function do you also college

00:27:32.520 function in fiends like is it like this is have a special name okay it's a

00:27:38.100 function a function so in this function to create a user they have this cast

00:27:43.370 function where they can say I'm only interested in the name and the email per

00:27:49.170 context because I'm gonna use this function only as a non admin user okay

00:27:54.540 and it's exactly the same introducer so instead of having it in sitting in some

00:28:01.590 random place we have the properties defined in our contract and the contract

00:28:07.320 is our operation so I use this operation as a non admin and I use another

00:28:12.750 operation with different fields for for an admin context for example so I don't

00:28:18.060 have to I don't have to deactivate features that I already

00:28:24.300 initially added for a special case I handle all my special cases with different classes of functions it is it

00:28:33.060 is so simple and I I really struggled to understand why

00:28:38.300 we why we make our lives miserable hard I am by by forcing

00:28:46.060 like people to push everything into MVC

00:28:51.170 even though what we do is not MVC yeah so a validation is not model

00:28:58.090 dependent and it's also not controller dependent so why don't we have a layer for the elevations yeah and the funny

00:29:06.530 thing is that lots of existing new frameworks

00:29:12.040 completely go into the direction of let's have one object per

00:29:17.830 context let's have one object to do one thing validation and in rails we still have this okay my

00:29:26.150 access control is in strong parameters which is awesome because it's a separate object it's actually cool but it's in my

00:29:32.390 opinion in the wrong place and my validation of the parameters once they are filtered happens in the model and I

00:29:38.840 might also do some like manual validation for example if there is a current user I have to check something

00:29:45.530 against I might do that in the controller because in the controller it's easier to access the current user and it is really hard to understand what

00:29:53.810 validation code is run in this context or in this context and this is not because the validation code is wrong

00:30:00.140 with anything it is because we don't have the right abstraction layers yeah we try to work with an outdated I don't

00:30:08.300 want to say fundamentally flawed but flawed design of objects and a lovely example how

00:30:16.660 api's and flaws were picked up by smart

00:30:21.860 people is the brand-new is it 2.3 the brand-new loli operator

00:30:28.900 also known as Keanu Reeves operator which has the following behavior

00:30:37.150 so you often have this case that you want to access a really really deeply

00:30:42.950 nested property of some nested object graph breaking the law of Demeter one hundred

00:30:48.680 thousand times but doesn't up and you always have to check like is the profile there yes then is yes so this is

00:30:54.920 actually code from from the rails guides and this is a really awkward and you have to go through like it's it's super

00:31:02.020 convoluted code to go to just to get some thumbnail URL or something yeah so

00:31:08.900 but you have this a lot because it could always be nil and you don't want to access a little bit because when you get the nil exception and we don't have

00:31:15.770 monads in Ruby yet so yeah

00:31:21.220 so what they did was they introduced tried inactive support a few years ago

00:31:27.170 and try basically allows you to go through the chain I think you have all used try actually if you use try you're

00:31:33.260 doing it wrong but you have this chain and you can write this chain in one line instead of in seven lines and it will

00:31:40.400 help you if there's nil it won't continue the the execution chain which is actually pretty cool so they people

00:31:46.220 saw hey this is really awkward in my existing API because we don't have an API for this case let's introduce tribe

00:31:52.610 and what's even cooler is that then ruby in 2.3 it was 2.3 right they introduced

00:31:59.330 an operator to do that kind of stuff so you don't even have to think about am i

00:32:04.520 using active support or not because i don't really use it oh sorry I said stop stop the ranting so

00:32:11.000 and they introduced an entire operator to handle this special awkward case of is it new or not and that's pretty

00:32:17.840 that's pretty fantastic because it is the job as I said earlier of a good

00:32:23.990 software developer to pick up here's a problem with my abstractions my API is

00:32:29.120 not entirely nice to use let's change it and that's exactly what happened with

00:32:34.520 the Keanu Reaves sorry the safe navigation operator where the Ruby core

00:32:39.800 team introduced a way to to treat execution chains and the bad

00:32:46.460 mill object that might be emitted in somewhere in this chain I wish we had

00:32:53.750 more operators like this but who knows Ruby 3.0 coming in when was it December

00:33:01.340 2 and 25 is coming and I'm sure it's gonna be packed with useful features the

00:33:08.419 Keanu Reeves operator when I appeared I was happy because I love it when people

00:33:14.929 add and extend their api's for the sake of better code but I also was a little

00:33:21.980 bit sad because it is a complete is it's another story to talk about is this

00:33:28.759 actually good code to have those long chains of responsibility in your code and I can already see how lots of people

00:33:36.409 jump on this feature and say yes let's use the lonely operator and we will save

00:33:43.669 ten lines of code and then they upgrade to Ruby 2 point 3 which is good and they

00:33:49.610 will think my code is awesome now because I'm using the lonely operator so one I happy laughing one eye a little

00:33:57.950 bit sad because it actually is and also

00:34:03.230 am a kind of dangerous tool because it might create the illusion your code is now perfect but if you have five level

00:34:11.060 deep chains in Excel to access objects you might have to rethink your structure

00:34:16.149 anyway I'm not here to talk about I actually I am here to talk about structures or whatever

00:34:23.109 a last feature I want to want to have is

00:34:29.589 or a problem that is crying for a feature is a new keyword or I'm a new

00:34:39.560 keyword and suggesting proposing whatever so when you use namespacing in

00:34:46.310 Ruby who likes to use name spacing in Ruby excellent this is an awesome audience

00:34:52.419 because nice racing is great let's say you have a class defined in

00:34:57.800 one file user dot avi and it's a user class and it is derived from active

00:35:03.020 record base it is totally fine in another file for example lip user

00:35:09.740 created a bean I want to namespace the create class into user yeah this is

00:35:16.950 how namespacing in Ruby works so there's different kinds of tricks and different kinds of tricks how to avoid

00:35:24.329 the problem I'm gonna talk about but it's all kind of has its benefits and

00:35:29.460 trade-offs and so if you use this way of name spacing you as excellent

00:35:34.680 programmers instantly see hey there is redundancy because I have this and this

00:35:39.779 twice and if I forget to add this for example in the in the

00:35:49.200 upper file Ruby will say hey stop here is a superclass mismatch if I forget it in this case Ruby won't say anything and

00:35:57.089 it will work because that's apparently a feature I was asking about that yesterday too I was asking Matz he said

00:36:03.269 it's a feature that's great if I load this file first without this then this

00:36:09.420 file will break and because Ruby doesn't know is it an active record base or is

00:36:15.150 it a is it not is it just a normal Ruby class so it is

00:36:22.549 no matter how you turn it you always run through this problem when you name space you have to be really careful with with

00:36:29.309 loading order and you have to be really careful with using the same inheritance - basically you have to be redundant to

00:36:37.980 satisfy Ruby which is cool because I don't want to have classes submitted with multiple inheritance but actually I don't want to think about this kind of

00:36:43.829 stuff I just want to say something like hey what if in the second file I just

00:36:48.869 say namespace user and Ruby will find out ah you mean the top-level user class

00:36:55.769 that is derived from active record base but in the second file the second file that is loaded I don't care about this

00:37:01.529 because I just say Ruby I want this user constant can you please give that to me

00:37:09.089 and nest they create the new create class into that namespace and this

00:37:14.400 feature is not existent in case you didn't know

00:37:19.529 there's no namespace key word even though I made it orange on the screen because I just I just marked them well

00:37:26.190 spaced and clicked font color orange so this feature is non-existent yet ah

00:37:31.369 but apparently it is already approved by the

00:37:48.540 is the way to do open source you just tell people what to do and they do it and in the end you can say oh I did that

00:37:54.750 I invented that by the way I'm waiting for whereas my there should be someone with a five minutes um sheet of paper

00:38:01.020 but no one wanted me my professional timer here warned me so what's what's

00:38:06.119 going on here what we you all love me it's gonna be such a

00:38:14.339 good party tonight so um I did try to show you some

00:38:22.349 examples when abstractions start leaking and I also

00:38:27.839 did try to show you how to solve that and usually this implies more than just

00:38:33.210 oh I'm gonna allow another argument in my method or I'm gonna change the method

00:38:39.000 name this is cosmetic little changes they do not help what you have to change is the structure of your code yeah

00:38:45.810 usually it's the structure so it's not about method names and method arguments it's about what object has this method

00:38:52.619 yeah and this is the really this is the hard part in software development is architecture and there's no book to tell

00:39:00.060 you how to find I mean these books how to find out how to when something is

00:39:05.070 wrong Martin Fowler refactoring an awesome book I gave it to a friend and

00:39:10.440 he still has it so I only read half of it so

00:39:16.550 it's a great book to find out those kind of to learn how to find out about those kind of problems

00:39:22.339 but there there's no book to tell you here is how you solve this problem and

00:39:27.810 here's how you solve this problem because you can read a hundred books about this design patterns they won't tell you how to solve you exact problem

00:39:34.200 but what you have to keep in mind when you encounter those kind of code smells

00:39:39.540 and that it's your job to think about a new API it's your job and it's also a lot of

00:39:47.420 fun to play with new architectural changes and to make sure that the new

00:39:53.150 API will probably solve stuff that might appear in the future because I could develop other things about what it can

00:39:59.570 happen in the future even though we can't see what happens in the future okay so changing api's is not wrong it's

00:40:07.100 not like oh I wrote code I have to change my API developer it's it means you're a good developer yeah always

00:40:13.730 think of this login form with where they suddenly said hey our abstraction of email and password I know it's a

00:40:19.700 horrible example but it doesn't matter it's not enough let's add some new functionality to log in with github that

00:40:25.790 was awesome it made everyone's life easier I don't have to remember my passwords anymore I can drink more akia

00:40:30.980 and and it still works okay so when you change your API is and your structure

00:40:37.670 you're doing it actually right and there's a couple of simple tricks you

00:40:42.910 will learn automatically for example the simpler your objects the less responsibility and object yes we had

00:40:49.100 some excellent talks about this at this amazing conference which has the after party on the first

00:40:56.600 day not the second day so there's some the simpler you design

00:41:02.690 your new API they're more likely you are on the right path okay but changing

00:41:07.790 stuff is not wrong and I hope that also existing huge API is found in rails will

00:41:16.130 slowly pick up this idea of hey maybe it's not okay to work with a

00:41:21.260 ten-year-old flawed MVC paradigm and instead of adding and

00:41:27.110 adding and adding new features which is awesome and I totally respect the work of the rails core team but I would hope

00:41:33.080 that new structural ideas and new architectural changes will be accepted

00:41:39.050 faster than 10 years to you know change something and

00:41:44.380 so the last thing I want to give you on your way before we all meet at the vitamin B after-party is

00:41:51.580 that if you change your IP yes you're being innovative and that is great so

00:41:58.270 you want innovation you want to cover you want to solve problems instead of

00:42:03.400 just ignoring them and or just like you know having some duct tape fix for this

00:42:08.950 kind of stuff you want to innovate your own code and that can only happen with change and not with looking at you

00:42:14.170 couldn't say oh I'm such an awesome programmer actually I do that all the time so the last thing you should know

00:42:20.470 is I really like him sunsets and

00:42:27.060 thinking you were an amazing audience and now let's go through vitamin B whoo

00:42:44.950 you

The Illusion of Stable APIs

EuRuKo 2016