Clean up your code with C#6

45
> < next previous C#6 A cleaner code

Transcript of Clean up your code with C#6

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C#6A cleaner code

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Clean up your code!

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Philosophy design

No New Big features … but many small ones to

to improve your code

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Clean up your code!

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Put C#6 In context

Let’s see how to improve our code with less boiler plate and more meanings

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The language

C#1

async/await ?

var, anonymous, Lambdas, auto-properties, line

Generics, partials, iterators, nullables

C#2

C#4 C#3

C#5 C#6

History

dynamic, optional parameters

2002 2005

2007

20152012

2010

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Developers should write their code to fit in a slide

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News

01 Using Static classeswhy bother with static class names?

020304

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String Interpolationbecause string.format sucks

Getter only propertiesbecause un-meaningful boiler plate

auto-properties initializersbecause creating a backing field for properties only don’t make sense

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Using Static 01using System;

public class Code{public void LogTime(string message){

Console.Write(DateTime.Now);Console.WriteLine(message);

}}

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Using Static 01using static System.Console;using static System.DateTime;

public class Code{public void Print(string message){

Write(Now);WriteLine(message);

}}

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Using Static 01Console.Write(DateTime.Now);

Write(Now);

From a very technical lineYou moved to a natural

language reading friendly sentence

using static allows removal of technical

boilerplate

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String Interpolation 02public void UserMessagesLog(string message, User user){

var messageToLog = string.Format("[{0}] {1} - {2}",DateTime.Now,user.Name,message);

Console.WriteLine(messageToLog);}

}

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String Interpolation 02public void UserMessagesLog(string message, User user){

var messageToLog = $"[{DateTime.Now}] {User.Name} - {message}" Console.WriteLine(messageToLog);

}}

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String Interpolation 02string.Format("[{0}] {1} - {2}",DateTime.Now,user.Name,message);

$"[{DateTime.Now}] {User.Name} - {message}"

sounds good enough for small strings, But…

we’re stupid, when you read the code, there will be a context switch to

interpret the result of your string if the value is not in the place you write it!

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String Interpolation 02public void UserMessagesLog(string message, User user){

var messageToLog = $"[{DateTime.Now}] {User.Name} - {message}" Console.WriteLine(messageToLog);

}}

Why waiting 15

years for that?

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Getter only properties 03public class Post{private string title;public string Title{get{return title;}

}public Post(string title){this.title=title

}}

C#2

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Getter only properties 03public class Post{public string Title { get;private set;}

public Post(string title){Title=title

}}

C#3

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Getter only properties 03public class Post{public string Title { get;}

public Post(string title){Title=title

}}

C#6

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AutoProperties initializers 04public class Post{private string id="new-post";public string Id{get{return id;}

}public Post(){}

} C#2

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AutoProperties initializers 04public class Post{public string Id {get;private set;}public Post(){Id="new-post";

}}

C#3

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AutoProperties initializers 04public class Post{public string Id {get;} = "new-post";

}

C#6

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News

05 Expression bodied propertiesbecause one expression is enough

060708

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Expression bodied methodstoo much braces for a one expression function

Index initializersbecause initializer shortcuts are great

Null conditional operatorsif null then null else arg…

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Expression bodied props 05public class Post{private DateTime created = DateTime.Now;public DateTime Created {get{return created;}

}public TimeSpan Elapsed {get {return (DateTime.Now-Created);

}}

}C#3

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Expression bodied props 05public class Post{public DateTime Created {get;} = DateTime.Now;

public TimeSpan Elapsed => (DateTime.Now-Created);

}

C#6

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Expression bodied props 05public class Post{public DateTime Created {get;} = DateTime.Now;

public DateTime Updated => DateTime;

}

C#6

Spot the difference

{get;} = value is affected once for all, stored in an hidden backing field

=> represents an expression, newly evaluated on each call

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Expression Bodied Methods 06public class Post{public string Title {get;set;}public string BuildSlug(){return Title.ToLower().Replace(" ", "-"); 

}}

C#3

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Expression Bodied Methods 06public class Post{public string Title {get;set;}public string BuildSlug(){return Title.ToLower().Replace(" ", "-"); 

}}

C#3never been frustrated to have to write this {return}

boilerplate since you use the => construct with lambdas?

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Expression Bodied Methods 06public class Post{public string Title {get;set;}public string BuildSlug()=> Title

.ToLower()

.Replace(" ", "-");}

C#6

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Index initializers 07public class Author{public Dictionary<string,string> Contacts {get;private set;};

public Author(){

Contacts = new Dictionary<string,string>();Contacts.Add("mail", "[email protected]");Contacts.Add("twitter", "@rhwy");Contacts.Add("github", "@rhwy");

}}

C#2

mailto:[email protected]
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Index initializers 07public class Author{public Dictionary<string,string> Contacts {get;} = new Dictionary<string,string>() {

["mail"]="[email protected]",["twitter"]="@rhwy",["github"]="@rhwy"

};}

C#6

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Index initializers 07public class Author{public Dictionary<string,string> Contacts {get;} = new Dictionary<string,string>() {

{"mail","[email protected]"},{"twitter","@rhwy"},{"github","@rhwy"}

};}

C#3

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Null Conditional Operators 08public class Post{

//"rui carvalho"public string Author {get;private set;};//=>"Rui Carvalho"public string GetPrettyName(){

if(Author!=null){

if(Author.Contains(" ")){

string result;var items=Author.Split(" ");forEach(var word in items){

result+=word.SubString(0,1).ToUpper()+word.SubString(1).ToLower()+ " ";

}return result.Trim();

}}return Author;

}}

C#3

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Null Conditional Operators 08public class Post{//"rui carvalho"public string Author {get;private set;};//=>"Rui Carvalho"

public string GetPrettyName()=> (string.Join("",

Author?.Split(' ').ToList().Select( word=>

word.Substring(0,1).ToUpper()+word.Substring(1).ToLower()+ " ")

)).Trim();

C#6

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Null Conditional Operators 08public class Post{//"rui carvalho"public string Author {get;private set;};//=>"Rui Carvalho"

public string GetPrettyName()=> (string.Join("",

Author?.Split(' ').ToList().Select( word=>

word.Substring(0,1).ToUpper()+word.Substring(1).ToLower()+ " ")

)).Trim();

C#6

We have now one expression only but

maybe not that clear or testable ?

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Null Conditional Operators 08public string PrettifyWord (string word) =>

word.Substring(0,1).ToUpper()+word.Substring(1).ToLower()+ " ";

public IEnumerable<string> PrettifyTextIfExists(string phrase)=> phrase?

.Split(' ')

.Select( PrettifyWord);

public string GetPrettyName()=> string

.Join("",PrettifyTextIfExists(Author))

.Trim();

C#6

Refactoring !

We have now 3 small independent functions with

Names and meanings

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News

09 Exception filtersnot new in .Net

101112

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nameof Operatorconsistent refactorings

await in catchwho never complained about that?

and in finallythe last step

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News

09 Exception filtersnot new in .Net

101112

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nameof Operatorconsistent refactorings

await in catchwho never complained about that?

and in finallythe last step

these ones are just good improvements but not that important for our code readability

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Exception Filters 09try { //production code

} catch (HttpException ex){ if(ex.StatusCode==500) //do some specific crash scenario if(ex.StatusCode==400)//tell client that he’s stupid

}catch (Exception otherErrors) { // ...

}

C#2

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Exception Filters 09try { //production code

} catch (HttpException ex) when (ex.StatusCode == 500) { //do some specific crash scenario }catch (HttpException ex) when (ex.StatusCode == 400) { //tell the client he’s stupid } catch (Exception otherException) { // ...

}

C#6

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nameof Operator 10public string SomeMethod (string word) {if(word == null)throw new Exception("word is null");

return word;}

C#3

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nameof Operator 10public string SomeMethod (string text) {if(word == null)throw new Exception("word is null");

return word;}

C#3

Refactoringarg, information

lost!

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nameof Operator 10public string SomeMethod (string word) {if(word == null)throw new Exception($"{nameof(word)} is null");

return word;}

C#6

parameter name is now pure code & support refactoring

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await in catch 11try { return await something();

} catch (HttpException ex){ error = ex;}return await CrashLogger.ServerError(error);

C#5

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await in catch 11try { await something();

} catch (HttpException ex){ await CrashLogger.ServerError(ex);}

C#6

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await in finally 12try { return await Persistence.Query(query);

} catch (PersistenceException ex){ await CrashLogger.ServerError(ex);} finally{ await Persistence.Close();

} C#6

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To FinishC#6 helps to be more functional & write cleaner code by

removing lots of boilerplate!

refactoring to small functions, add new words to

your app vocabulary

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Thanks

@rhwy

ncrafts.ioaltnet.fr

rui.io

http://ncrafts.io
http://altnet.fr
http://rui.io

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