[fluent] dart function (function composition | private function | anonymous function | function summary)

One 、Dart Function constitution

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Dart Function constitution : Method name , Parameters , Return value ;

return type :

• ① default : The return value type can be defaulted ;
• ② Empty type : The return value type can be set to void ;
• ③ The real type : The return value type can be set to the real data type ;

Method name :

• ① Anonymous methods : No method name is required ;
• ② Common method : Methods other than anonymous methods require method names ;

Parameters :

• ① form : Parameters include Parameter type , Parameter name ;
• ② Type default : The parameter type can be defaulted ;
• ③ Parameter classification : Optional parameters , Default parameters ;

Examples of standard methods :

  ///  Standard method   ///  The return value is  int  type   ///  The function name is  sum  ///  Parameter is  int num1, int num2  int sum(int num1, int num2){ 
        return num1 + num2;  }

Two 、Dart Private functions

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Private method :

• brief introduction : Only methods that can be accessed in the current file are called private methods ;
• Format : Underline the method name , Identifies that the method is private ;

Private method example :

  ///  The method is private   int _minus(int num1, int num2){ 
        return num1 - num2;  }

3、 ... and 、Dart Anonymous functions

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Anonymous methods : Only parameter list and method body , No method name , Anonymous methods can be assigned to a variable ,

Anonymous methods And Naming method Corresponding , The common way is to name ;

The anonymous method format is as follows : In parentheses is a list of parameters , In braces is the method body ;

( Parameter type   Parameter name ,  Parameter type 2  Parameter name 2){ 
    	///  Anonymous method body };

Anonymous method example :

  ///  Anonymous method example   anonymousFunction(){ 
        var list = ['Tom', 'Jerry'];    list.forEach(        ///  The following method is anonymous ,  Only parameter list and method body         (i){ 
              print(list.indexOf(i));        }    );  }

Four 、 Complete code example

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class Function{ 
      ///  Standard method   ///  The return value is  int  type   ///  The function name is  sum  ///  Parameter is  int num1, int num2  int sum(int num1, int num2){ 
        return num1 + num2;  }  ///  The method is private   int _minus(int num1, int num2){ 
        return num1 - num2;  }  ///  Anonymous method example   anonymousFunction(){ 
        var list = ['Tom', 'Jerry'];    list.forEach(        ///  The following method is anonymous ,  Only parameter list and method body         (i){ 
              print(list.indexOf(i));        }    );  }}

5、 ... and 、Dart Methods to summarize

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Entry method : stay main.dart Medium main() Method ;

void main() => runApp(MyApp());

Construction method : Reference resources 【Flutter】Dart object-oriented ( Name the construction method | Factory construction method | Name factory construction method ) Naming construction method in blog , Factory construction method, etc ;

getter and setter Method : Use get and set How to define keywords , Reference resources 【Flutter】Dart object-oriented ( get Method | set Method | Static methods ) Blog ;

Static methods : static Methods of keyword modification ; Reference resources 【Flutter】Dart object-oriented ( get Method | set Method | Static methods ) Blog ;

Abstract method : There is no method body method ; Reference resources 【Flutter】Dart object-oriented ( abstract class | Abstract method ) Blog ;

Private method : Method names begin with an underscore ;

Anonymous methods : Only parameter list and method body , No method name ;

6、 ... and 、 Related resources

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Reference material :

• Flutter Official website : https://flutter.dev/
• Flutter Developing documents : https://flutter.cn/docs ( Strongly recommend )
• official GitHub Address : https://github.com/flutter
• Flutter The Chinese community : https://flutter.cn/
• Flutter Practical tutorial : https://flutter.cn/docs/cookbook
• Flutter CodeLab : https://codelabs.flutter-io.cn/
• Dart Chinese document : https://dart.cn/
• Dart Developer website : https://api.dart.dev/
• Flutter Chinese net ( unofficial , The translation is very good ) : https://flutterchina.club/ , http://flutter.axuer.com/docs/
• Flutter Related issues : https://flutterchina.club/faq/ ( It is recommended to watch it at the introductory stage )

Blog source download :

• GitHub Address : https://github.com/han1202012/flutter_app_hello ( Keep updating with the progress of the blog , There may not be the source code of this blog )

• Blog source snapshot : https://download.csdn.net/download/han1202012/15452191 ( The source code snapshot of this blog , You can find the source code of this blog )