Let, Also, Apply, Run, With - Kotlin Scope Functions

[@AlaaAlbrg]

Summary of Scope functions: let: Used to check nulls, also better than simple null check in multi-threading case also: same as 'let' but it doesn't return the last line as 'let', instead 'also' will return the object it was called on and 'not the last line!' apply: helpful function to modify objects, if you want to change in properties of the objects, and it uses 'this' instead of 'it' as we work inside the class of the object run: equivalent to 'apply', but it won't return the object it was called, instead it will return the last line with: same as 'run' but a different signature.

[@PhilippLackner]

good!

[@trungtrankim294]

Awesome. Thanks a lot man.

[@rithulraj3348]

*with()* is the combination of *let* and *run* because it does null check also, am I right?

[@hazfrd]

@@rithulraj3348 nope. In fact run is combination of with & let. Run does check nullpointer (let) and reference with this (with) , after that return the last line a.k.a lambda expression

[@hazfrd]

@@rithulraj3348 with() doesn't checking null, just for non-null. in case it is null then use let(), in case you want make some operation while checking null then use run()

[@codinginflow]

11:04 sick special effects bro .also { respect++ }

[@PhilippLackner]

pow(thanks, 10)

[@johnybaby9574]

Hi CiF~!

[@codinginflow]

@@johnybaby9574 hi

[@agp1444]

also is very useful in case x = y.also { y = x } - switch values of variables without third variable

[@mahdi7236]

big brain time😉

[@TheMohit987]

😂😂😂😂 wow

[@hieuluu2495]

Awsome

[@phamhung2263]

why don't we just switch those variables with a third variable. It's more readable

[@disgruntled_llama]

@@phamhung2263 or write a function called "swapValues(x, y)" and use that. That's the most readable.

[@damercy]

Hey man. I just learnt Kotlin. Previously I've made a few basic projects in android using Java. Fortunately,I found your channel with some really good resources to learn android dev in Kotlin. Just wanted to say a genuine thank you for putting out such great content. Please don't stop. Power to you! 🔥❤️

[@PhilippLackner]

Thanks! You're totally welcome

[@mirzasohailhussain]

Thanks Philip, you are sharing so much knowledge without any charge. I have seen so many people share only basics and then member only videos

[@larrystreehouse1124]

Simple and Concise explanation. Even though I go self-learning with Kotlin for 1 year, this is great to recall my memory and consolidate my knowledge. More importantly, you show us how to teach and explain the basic concept in an interesting and concise passages with live examples.

[@firuzaaliyeva5382]

Was literally just thinking about finally studying these, and you just uploaded. Thanks!

[@iJuce]

same wtf

[@PhilippLackner]

yes, I can read your mind

[@mz-coder]

@@PhilippLackner LOL!

[@weather120widget8]

I really appreciate your teaching style, how you build on topics as you go. Keep up the great work.

[@2chotti]

This is the best video on scopes. Thanks

[@benjaminmorales8624]

You’re an amazing dev, thank you for all this effort and please keep it rocking!

[@PhilippLackner]

Thanks, will do!

[@ziakhan-tk7rk]

Your tutorials are addictive I watch them repeatedly

[@rahimovdev]

even so it was made 4 years ago , it's very useful that i've ever found

[@ganshakumari5196]

Fantastic explanation. Much clearer than most of the online resources, Thanks Mate!

[@salimmazariboufares3118]

Cool, that was pretty much understandable by someone who is new to Kotlin.

[@TheMohit987]

Your videos are very helpful. Your way of teaching is simply awesome.

[@thearpansircar]

An absolute psychic. I was going through Kotlin's Documentation and, suffice to say, it confused the fuck outta me.

[@FatalRescue]

Wow, thank you for opening my eyes. I was just using let as shorthand for the null check and did not realize how useful it actually is!

[@PhilippLackner]

yes, let > null-check

[@ianlipa9826]

Your tutorials are a big help bro. Thanks!

[@FreeKnowledge]

Fantastic explanation.

[@carloscambon5402]

You explain very clearly. Thank you.

[@tanishqsehgal2593]

Very Well Explained

[@usherg4158]

o man, I have been reading lots of explanation and still not get it until watching yours. Great example and explanation, thanks for making this video.

[@achalbadgujar9519]

Finally a practically helpful explanation of these scope functions

[@telurasinmontasik2406]

Very clear explanation

[@indraj6669]

Great explanation

[@lyawileh.a8741]

Thanks for useful explanation. 🙏

[@rahulchandrabhan]

One of the best explanation. Simple and Easy. Great man

[@PhilippLackner]

Glad you liked it

[@adarshdev3810]

It is awesome you explains concepts so simple. Hats off

[@mahetachirag8395]

Your tutorial are awesome.

[@MyPhoneNotAccount]

so much better than the kotlin udacity explanations

[@aweklin]

I already liked the video before watching because it is the topic I had pinned on my todo list to research this week. Thanks Philipp

[@PhilippLackner]

Awesome, thank you!

[@marinbeslo7841]

your tutorials are just awesome!

[@PhilippLackner]

Thanks a ton!

[@walkmn]

Good explanation for the latest one 😄

[@LittleWasteClub]

Thank you for the great explanation!

[@rsobies]

in this case number is a property so it is a function. a function can return different results and that's why it is considered as mutuable. inside let block you are dealing directly with a field of the class. 'it' is a field, not a property. so it is immutable

[@jackli1924]

Awesome video！You explained very simply and concisely. Thanks a lot Philipp!

[@aneessaleh2870]

amazing video mate , keep it up please

[@PhilippLackner]

Thanks a lot!

[@DreckbobBratpfanne]

i liked to use with eg in viewbinding, because then i can avoid typing the binding variable name xD, also you can use multiple of them within each other what is also pretty nifty

[@mdjahidulislam9205]

I was waiting for it.you just read my mind

[@PhilippLackner]

yes, I did

[@anvarzaripboyev5730]

Thanks bro, it is very usefull tutorial. Good luck!

[@Qrzychu92]

I don't even programm in Kotlin (fellow dotnet dev here!), but this videos are very cool :) I'd love to have this tuff in C#

[@tomaslopez9999]

Thanks for creating this video.

[@zareahmer5949]

You are Great man . Stay blessed

[@yuanyuechen2183]

Thank you, I really learn a lot from you

[@leosvxy]

thank you! , was so easy to understand your explanations

[@imagetag4618]

Wow. its so much clear understand. thank you. keep it up.

[@TheMaciak90]

Very well explained. Thank you mate.

[@vibinjoby]

Amazing just what i wanted after reading the docs and wondering where exactly all these get used

[@Alvin-dg9pq]

Fantastic explanation, thanks a lot.

[@r.j.jeninjoseph4975]

Really helpful thanks man

[@original_anu]

Simple, crisp explanations ❤

[@ajaykumarvishwakarma4720]

Really informative video. Thanks a lot

[@theonlyarjun]

just what i was searching for, awesome man

[@PhilippLackner]

Glad to hear it!

[@techmarinar]

Thanx man this was very helpful 😊

[@yuripanov9670]

You're the best! Thanks!

[@hirarkiardipratamakiki8777]

i often use 'with 'to declare componen with viewbinding,such as onClickListener, and etc.

[@bjugdbjk]

Such a fab explanation, Thanks a ton, You should really do a lot more this kind of standalone videos of advanced concepts of Kotlin, it will b super helpful.

[@PhilippLackner]

Thank you!

[@koutheirelbehi4384]

This boi is on another level !

[@lional4898]

With is useful when using string builder. No need to create new variables. Simply call toString at the end

[@ankitpareek8979]

I have an usecase where i need to call a suspend function(some network call) on completion of it i need to perform other local task. I am trying to use also there but getting unexpected results. Can u explain this !!!

[@aunghtayoo337]

Thanks. Philipp

[@mehdiparsaei1867]

The best in the world! I am sure!

[@tyrannus00]

Schönes Video, gut erklärt 👍

[@MrLukasw44]

but is that mean that apply is thread safe? so if we got an object and we would like to run 3 methods on that object and that object is a global variable so the question is if we use apply those 3 operations will be thread safe?

[@mohityadav21]

Shouldn't it be it++ instead of i++ at 6:19?

[@himanshugoeldelhi]

Try executing that code if some people don't understand what 'let' does number?.let { number = null val num2 = it + 1 } Here 'let' actually saved the global value of number and even in case number becomes null in 'let' block , still 'it' value will remain the same which you defined before

[@dreamer6228751]

Thanks bro, it's excellent video !

[@PhilippLackner]

You're welcome!

[@sckly43]

awesome video bru

[@abdelsttarahmed8821]

you are legend man i wish seeing you doing a video on Providing offline capabilities with NetworkBoundResource

[@PhilippLackner]

I do that in my ktor course on pl-coding.com

[@imnithish]

great vid as usual man

[@PhilippLackner]

Glad you enjoyed it

[@themichael8767]

Thank You very much, Sir!)

[@ucPhamQuoc]

the beard is impressive

[@alexnovikov1609]

Thank you!

[@abhikhandelwal8253]

All these Scope Functions are not showing in android studio ? it gives me an error and said make a external function for using these function why?

[@ramakrishnavjoshi]

Thanks for this video, Philipp. :)

[@nishantpattani3053]

what is difference between return@let and simple return in let function

[@serhatcd]

Thanks for video.. Also i see use function. What is the use function? This is also scoped function

[@brucebane7401]

amazing tutorial!!!!!

[@shidqi100]

Great video expected man love your explanation, just asking will you make videos outside topic of android and mobile dev in general ex: Ai, web or desktop?

[@PhilippLackner]

Not planned right now, but I also don't say I never will. I might do some flutter videos in the next time

[@mohammedelamin1563]

So helpful 😎

[@VeronikaDoma-f5y]

Thank you!! 🤩

[@thedeadserv]

lol yo dude the beard! you can definitely make it work but clean is your jam :D tks for the video!

[@RackaApps]

Super helpful

[@kor21727]

I think 'with' is good in case of referring an object multi times. ex) binding.textA.text = "textA" binding.textB.text = "textB" ====> with(binding) { textA.text = "textA" testB.text = "textB" }

[@PhilippLackner]

Same as apply

[@tejas5331]

Hey can you tell me how to fetch data about places from API and show on Map in Android?

[@jasperjohnsoncalapini]

Can I do something else inside 'apply' and 'run' for example textbox.run { //is this a good practice val x = 10 val squareX = x*x // or maybe some loops text = "$x" } and one more thing, would you prefer 'apply' over 'run' when when modifying views/components in android? Thanks

[@PhilippLackner]

no, I would move out of these functions whatever you can move out, this doesn't look very readable to me. If you just modify views and don't care about the return value it doesn't matter if you use apply or run

[@ramakrishnavjoshi]

Why this does not product compile time error? var nullableField : String? = "" nullableField = "123" val nonNullableField : String = nullableField

[@PhilippLackner]

Because the compiler is smart enough to see that nullableField is never null. Set it to null in between and it should give you an error

[@ramakrishnavjoshi]

@@PhilippLackner Got your point but what if another thread assigns null to nullableField before it is used in third line? Edit: I think this is why there is a need to use let operator and consume `it`. Am I right?

[@PhilippLackner]

@@ramakrishnavjoshi there is no way another thread can change it back to null in your scenario because the thread must be launched between the declaration of nullableField and nonNullableField and if you do that you get an compile error again. If you do the same, but declare nullableField globally you will get an error without setting it to null somewhere

[@ramakrishnavjoshi]

@@PhilippLackner Got it. You summed up nicely. I was under wrong assumption that a nullableField can not be used to initialise nonNullableField.

[@fourcade7851]

Thank You Bro

[@PhilippLackner]

No problem

[@mohamadalighezelbashyan4482]

Great!! thanks ❤

[@coffeedude]

I learnt that you can use 'also' to swap variables but I don't understand why it works. ie: var foo = "foo" var bar = "bar" foo = bar.also { bar = foo } print(foo + bar) // barfoo

[@soontaek]

I left you some feedback on your previous video (Preference Datastore)

[@PhilippLackner]

Thanks, I saw it! :)

[@vikasdaily122]

How squaredFunctionI = (i*i) can be a function without return type and body.

[@mandroidx1474]

Appreciated Keep it up❤

[@PhilippLackner]

Thank you, I will

[@abuiman5251]

Thanks!

[@pratikchauhan989]

Good one 👏👏

[@PhilippLackner]

Thanks ✌️

[@riyupapa39]

I usually use run like this var a:String?=null //When i want do something if only a is not null, a?.run{ //todo }

[@scottbiggs8894]

I never realized before that Philipp looks like the Elvis operator ?: ;)

[@andriibibik39]

Very Good!

[@jayeshsuthar5590]

crystal clear....

[@sudarshanh.s.521]

this is awesome