How To Create Extension Methods in C#
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- Опубліковано 22 лип 2024
- Extension methods allow us to add functionality to systems we don't control. They also allow us to write code that is easier to read. In this video, we are going to go over what extension methods are, how to write them, and when to use them.
Source Code: leadmagnets.app/?Resource=Ext...
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0:00 - Intro
3:16 - Creating and using extension method
8:15 - Extension method classes and namespaces
10:59 - Extending methods from third party libraries
19:48 - When to use extension methods
21:30 - Extending methods for interfaces
23:03 - When not to use extension methods
27:01 - Summary and concluding remarks
Thanks Ralfs HBK
So many tutorials on the web, but I get the feeling your are the dean of developers.
Thank you!
Great video. Tim, thank you for such a detail, organized, and straightforward demonstration of method extension. You really are making C# easy.
That is his goal, thanks for watching.
Wonderful, very helpful lecture this is! Thanks, Tim. After seeing this class, I am eager to know the counterparts on properties or fields.
Thank you! I followed the tutorial and then created the .sln/.csproj on my own. Very nice intro to extension methods. Now, with great power comes great responsibility!
You are welcome.
I'm very happy because this is the first time I did know how to do all the things that this video has demonstrated. Yeiii!! Thank you Tim, you're the best!!!
Excellent!
I've used extension methods, but only ones I found. I had a bunch saved/bookmarked. I honestly thought it had to do something with how you named things or something in the standard libraries I just wasn't aware of... it was just "this class". It makes so much sense now!
Thanks for watching.
It is good video. you explain the start up writing on extension methods in seperate class and meaning the this key word more super. i confused in this understanding but now i am so clear. Thank you tim corey
Glad it was helpful!
Excellent lesson as usual!
I am using my extension methods for manual mappings when I need to convert Model to DTO and vice versa. It works like charm.
Great!
Perfect timing! Just when I thought where to implement extension methods in my pet project for portfolio.
He did not cover it, but he has a mind reading extension also. Just kidding!!!
That was amazing. Learning things so quickly with these tutorials. Thanks Tim.
You are welcome.
Gotta say it physically hurt when you put your extension class in the System namespace, good thing you mentioned that it should NOT be used like that.
Perfect timing and found your tournament course also using this technique for the textConnector
Great!
Thanks for this Tim. One interface I frequently extend in most libraries I write is the IServiceCollection so that setting up dependency injection for the library is easier to consume. I appreciate your expertise on these topics.
That's great can you provide sample extension code implementation for IServiceCollection?
Thanks for the tip
Thanks Tim. The way you make me understand is awesome.
Glad to hear that!
Thank you, I have been looking for a good tutorial on extention methods, popped up at a great time.
Thanks for trusting Tim for your training.
Thank you, I had seen these syntaxes before but I never knew what it did.
Good luck with your implementations of this. Please give us updates!
I'm still a student, and I promise you, you will receive a portion of my first salary. Thank you so much for these valuable resources. You couldn't imagine the feeling of joy when I search for a topic and find one of your videos among the results.
I am glad they have been helpful.
Hi, Tim! You're a great teacher!
Thanks!
@@IAmTimCorey
Request for future discussion Video -
* there was a thing called Params array in .net standard fmwk. If it still exists,
A good, elaborate code discussion video on same.
Thanks
Thank you for this informative video, I am learning .NET concepts wise and this really helped clarify the purpose of extension methods!
Thanks for trusting Tim for you training.
Thank you, Tim! It's a great course!
Thanks for watching
That's exactly what they are demanding me to know. Thanks for awesome content
Glad the timing was right for you. Please consider subscribing.
Another great one Tim!
Thanks!
Great video and great topic....too many people out there don't use that feature
Please help us spread the word!
I knew the first part, but that string at 7.30 just blew my mind.
Great!
Excellent tutorial! Thank you very much.
Thanks for the endorsement
Looking forward to seeing some videos about DDD, Microservices, and ElasticSearch.
I noted your recommendation by adding it to Tim's list of possible future topics, thanks.
Needed this last week! Thanks though
Well, better late than never, I guess.
awesome tutorial! Thanks
You're welcome!
Hey Tim. What's your opinion in using PostSharp? For example, in logging. And AOP in general. Just going through a Clean Code C# book and it is implementing it to keep some code with DRY and SRP.
Thank you!!! simple to understand :)
Thanks for trusting Tim
I actually found lots of good use for extending even the string type. For example, I have an extension where a person has a month spelled out and it returns the number from 1 to 12. Another one I have for strings is if a person has a sentence and need to know the month integer found in the string, then I have it as well. Even being able to easily generate a comma delimited list. The truth is even for the simple types like string ,integers, there are many useful extensions that can be created. One good one for int is being able to convert to any enum as long as the number sent matches the number it corresponds to in the enum. There are many other examples of good extensions for all simple types.
Thanks for the tips!
0:00 - Intro
3:16 - Creating and using extension method
8:15 - Extension method classes and namespaces
10:59 - Extending methods from third party libraries
19:48 - When to use extension methods
21:30 - Extending methods for interfaces
23:03 - When not to use extension methods
27:01 - Summary and concluding remarks
Thanks - you ROCK!!
@@tomthelestaff-iamtimcorey7597 check the 10 : 59 typo
Hey Tim, thanks for a great video and channel. Was just also watching your async video. Do u have any plans on making a Thread video as well?
I added it to Tim's list for topics to consider. Thanks for recommending it.
Holy shit why had no one taught me this sooner! Awesome
Seriously!
I’m glad it was helpful.
very well as always. Thanks
Thanks for watching
Love these things. Been using them for awhile, they write and read much easier. I like to wrap existing string functionality so I can do:
string myString = "";
if (myString.IsNullOrEmpty()) ...
and then just have the extension method like so.
public static bool IsNullOrEmpty(this string str)
{
return string.IsNullOrEmpty(str);
}
Or better yet, when writing logic to append a middle name...
public static string AppendIfNotNull(this string str, string textToAppend, string separator = ", ")
{
if (textToAppend.IsNullOrEmpty())
{
return str;
}
return $"{str}{separator}{textToAppend}";
}
Thanks for sharing
Every word count, thank you so much
You are welcome.
what if you want to overwrite a value set by a parent in the extension class?
I am new to C# and I really like your way of teaching.I have request could a make a video on various commands in C#
Check his videos, he has an intro to c#
Its overkill, but try this - ua-cam.com/play/PLLWMQd6PeGY2GVsQZ-u3DPXqwwKW8MkiP.html. There is no 10 min video for it, but you can grow your skills in a logical path.
Thank u Tim keep up the good work
Thanks Tim
You are welcome.
Your videos have been REALLY helpful. Thanks for everything you do!
Question: will you be doing anything on TDD? I'm having trouble wrapping my head around it...mainly where and how to start. I'm about to start developing a new website for my work and am trying to wrap my head around TDD for it
Nothing up to this point. I have added your recommendation to Tim's list of viewer suggestions for videos.
@@tomthelestaff-iamtimcorey7597 pun intended.. at first glance I thought the name was anti-this-channel
It is really helpful.
Great!
Hi Tim. Would you consider it a good practice to implement serialization as extensions to model classes? You touched on it briefly in your video, but it occurred to me that implementing serialization as extension methods makes it easier to switch from say XML to JSON without having to touch the model class(es). You just have to write some new extension methods. Or is it a better way of implementing serialization?
Never thought of that. Interesting..
thank you Tim , can you please how we can Mock Testing our Extention Methods as they are static
I added your suggestion to Tim's viewer requests list. In the mean time, have you watched this video on Mock testing from Tim - ua-cam.com/video/DwbYxP-etMY/v-deo.html
Great video! I'm looking for somethings similar but for properties. Any way to do this in c#?
Extension methods apply to types, so that means properties. For instance, if you have this code:
public string FirstName { get; set; }
Then this extension method would apply:
public void SayHi(this string name) => Console.WriteLine($"Hi { name }");
Excellent video, should have learned this sooner! For a future video, would it be possible to do more in depth mvvmcross videos? Thanks for all the great content, best teacher ever award!
Thanks for the recommendation. I have added it to Tim's list of viewer suggestions for videos.
@@tomthelestaff-iamtimcorey7597 Could not ask for more, Thanks!
Two thumbs up!!
Thanks!
Hey Tim, Am I able to extend Form to add a property? I want Form to have a selectedItems property
Yep. It is a class so you can treat it like any other class.
Idea for next video topic: SharedProjects - what is it, when use it, pros/cons. Thank you.
Tim addresses a lot of that in ua-cam.com/video/SXbRu6XcyMY/v-deo.html. Visual Studios sharing function and using it to work on collaborated projects.
Thanks!
You are welcome.
Thanks a lot. Very Clear Examples.
You are welcome.
I think that key word is "extension". Somethings not needed in my real program-flow. Is it right? 😉 But your lesson is landed right. .. ;) sorry for my english.
If you're not careful with extension method use, it can really make unit testing hard.
That is true.
Complex numbers class from Numerics does not have any Parse method
"Prototypes" of this Parse methods can be
public static Complex Parse(string? )
public static bool TryParse(string? out Complex)
Can this methods be written as extension methods
Sure.
Tim have you ever done something on Merge Conflicts in VS?
Tim has a couple videos on VSCode which can be used to resolve issues like Merge Conflicts. I would post the links but UA-cam deletes the comment if I do. Video names are "Intro to VSCode for C# Developers - From Installation to Debugging" and "Real-time Collaboration with Live Share in Visual Studio and VSCode"
Hi Tim,
How about the performance of an extension method? how can we measure it?
You time it with a stopwatch.
It was really good. But all methods are void because of the logging operation doesn't need a return type.
If you wanted to add features to a 3rd party library, wouldn't it make more sense to create something like a proxy to it and put the helper methods in the proxy instead? Dart supports extension methods too (seems like they are copying c# features or the other way around). Either way, I didn't stumble on a use case for them yet... I did see other people using them to share methods between classes. Don't know if that's a good use case though.
That's a lot of extra work and it provides you with something you need to support. I don't see how creating a proxy adds value over an extension method. Extension methods are simpler. By the way, you've used extension methods in your C# code even if you didn't know it. Microsoft makes heavy use of them. Almost all of the items off of IServiceCollection are extension methods (AddScoped, AddTransient, AddSingleton, etc.) Also, when we use Dapper, it is basically a couple of extension methods. It extends the IDbConnection interface to add Query and Execute.
@@IAmTimCorey Fair point. I'll definitely keep extension methods in mind. Specially since I already see the pattern being used.
This could be handy for IEnumerable classes.
Yep.
I extended DateTime to add a method that can calculate what we call here in Chile Working Days (Mon - Fri) since some stuff will take for example 10 Working Days, and i will like to know on which date those 10 working days will be done, also added an overload that will let you consider the current day as a working day. If any one wants it i can upload to my GitHub... any ways.. i will probably will be modifiying it so you can also pass an array of days you want to exclude from the calculations, lets say you know the 4th of July this year on on Tuesday, since it is not considered as a "working day" you can exclude it, but for now, that is just an idea! :)
Great examples!
I love extension methods because it makes code clean and readable. But I found that it's difficult to write tests against these extension methods since they are all static methods within a static class.( For instance, they cannot be mocked)
This is true. However, you can treat them like private classes and not extract them usually. Just test their effect. You can also override them with an actual instantiated method if you write them against an interface.
How do you unit test/Mock a class that uses an extension method.
Tak!
Extension methods. So simple and yet so powerfull. Again one of the most elegant and simple explainations. Why spend hours on books when 25 minutes with you along-side brings people up to speed. Love these simple examples and explanations. Supporting you!
Thank you!
Is mixing relevant in the world of C#? If so, can extension methods be used to achieve it?
I'm not sure what you mean by mixing.
@@IAmTimCorey it was a typo, mixin
ily.
Thanks Tim, are you able to put the link to the source code in the comments?
It is in the description.
This is great, now I can create an extension for TextBox that tells me if the text is empty. textbox.isEmpty() looks better than string.IsNullOrEmpty(textbox.Text.Trim())
Nice! Thanks for sharing it with us!
Use string.IsNullOrWhiteSpace
ty
You are welcome.
Please also make video on identity server4!!
Thank you. I have added this to Tim's list of possible future topics.
Ok Tim, here's a challenge for a video. I always hit a speedbump when I'm working with timed loops, so here's a scenario. You have an API project using a SignalR Hub. Anyone can subscribe to your hub to get data over intervals, but you don't want a million queries to be triggered to your database. You settle on a timed loop that 1. Queries the database. 2. Activates your Hub to send messages to it's subscribers. You can use any type of data here... Stock Tickers, Sports Scores... doesn't matter. Architecturally, which timer would you implement, and how would you allow people to get message at custom intervals. Say their choices are to receive messages every 10, 20 and 30 seconds. Also, the loop shouldn't run unless at least one client is subscribed. That would make an interesting video I think.
Thanks for the suggestion. I have added it to Tim's list of possible future topics.
It seems like visitor design pattern
The way you speak in this video in particular feels faster than usual or it's just me?
Not sure. I don't think I was rushing, but maybe I was.
Yeah .. Oriented choose implements .
Thanks!
You are welcome.