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Author: Ashwinee Kumar Dash.

Name of the Book: Essential ActionScript 3.0 by Colin Moock

Copyright: Creative Commons License
Disclaimer: Anything in quotation marks is a direct quotation from Essential
ActionScript 3.0
. All other notes are my own summaries of the concepts
presented in the book.

These notes are for reference purpose only and not intended to replace the book .Therefore I would strongly advise you to read the original book as well as make your own notes wherever necessary.

Send your suggestions and feedbacks to aswhineedash[at]gmail[dot]com or aswhinee2004[at]gamil[dot]com.

Data Type

  • Data Type means a set of values.
  • Null, void and object are three data types in AS.
  • Null has null value
  • Void has undefined as its value
  • Object includes all the instances of all the classes in ActionScript.
  • Each class creates a unique datatype. Its values are the instances of the class itself and its subclasses.
  • Any given subtype is compatible with its supertype and likewise a supertype is incompatible with its subtype. That’s because an instance of subclass can be treated as an instance of its superclass.
  • A type annotation or type declaration is a suffix that constrains the datatype of a variable parameter or function return value.
  • Type declaration is preceded by colon “:”.
  • In case of variable or function parameter the data type must be a class or interface.
  • In case of return type the data type must be a class, interface or void.
  • They can take * as data type which means untyped.
  • 3 situations where data type mismatch error is ignored in strict mode until runtime (1) untyped expression assigned to typed variable or parameter or returned from a function with a declared return type (2) any expression assigned to a typed variable or parameter with Boolean datatype or returned from a function with a Boolean return type (3) any numeric type is used where a different numeric type is expected
  • To detect reference errors compiler relies on type annotations.
  • Compiler checks the method definition in the class or interface which is specified by variable’s type annotation.
  • Compiler does not check the actual class of the value.
  • To avoid such errors at the compile time cast operation is used.
  • Cast operation tells the compiler to treat the expression as a specified type.
  • Type (expression).
  • At the runtime if the expression resolves to the specified object, it is returned.
  • If it does not resolve to a specified object, either it is converted to a primitive datatype or an error is generated.
  • Casting an object to its supertype is known as upcast
  • Casting an object to its subtype is known as downcast.
  • Upcast never generates an error
  • Downcast has the potential to generate error
  • To check the data type of an object, the ‘is’ operator is used like (expression is type) which returns a true or false value.
  • A cast operation can be used to convert any value to a particular primitive type.
  • When a variable is declared without a type annotation and without an initial value, its value is set to undefined.
  • If a variable is not initialized, it takes the default value of its datatype.
  • Both null and undefined means absence of data
  • The null value represents the absence of data for variables, parameters and return values with any type annotations except Boolean, int, uint, and number
  • Undefined represents absence of data for variables, parameters or return values without any specified type annotations
  • Undefined also means complete absence of variable or method on an object whose class is defined as dynamic
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Author: Ashwinee Kumar Dash.

Name of the Book: Essential ActionScript 3.0 by Colin Moock

Copyright: Creative Commons License
Disclaimer: Anything in quotation marks is a direct quotation from Essential
ActionScript 3.0
. All other notes are my own summaries of the concepts
presented in the book.

These notes are for reference purpose only and not intended to replace the book .Therefore I would strongly advise you to read the original book as well as make your own notes wherever necessary.

Send your suggestions and feedbacks to aswhineedash[at]gmail[dot]com or aswhinee2004[at]gamil[dot]com.

Instance Methods

  • The keyword this can be omitted as ActionScript automatically searches for the instance variable or method unless there is a local one available matching the search result.
  • Usage of the keyword this is legal only in the following cases instance method, constructor method, functions and code in global scope.
  • Method can be assigned as value to variable and again can be invoked through that variable. Such methods are known as bound methods.
  • This is most used when one section of program wishes to instruct another section of the program to invoke a particular method on a particular object.
  • Get method is used to retrieve the value of the private instance property
  • To define get method get keyword is used.
  • Get methods have a return type as they have the return value
  • Similarly set methods are used to modify the values of variables.
  • To define a set method set keyword is used.
  • Unlike get methods set methods do not have return values.
  • To invoke set or get methods “()” is not used.
  • In case of set methods a value is assigned rather than any arguments are passed
  • To deal with unknown number of parameters ….(rest) can be used where (rest) is the array of arguments. Just like any array arguments can be retrieved using array index.

Author: Ashwinee Kumar Dash.

Name of the Book: Essential ActionScript 3.0 by Colin Moock

Copyright: Creative Commons License
Disclaimer: Anything in quotation marks is a direct quotation from Essential
ActionScript 3.0
. All other notes are my own summaries of the concepts
presented in the book.

These notes are for reference purpose only and not intended to replace the book .Therefore I would strongly advise you to read the original book as well as make your own notes wherever necessary.

Send your suggestions and feedbacks to aswhineedash[at]gmail[dot]com or aswhinee2004[at]gamil[dot]com.

Static Variables and Methods

  • Static variables are class variables, not instance variables. Static variables do not vary from instance to instance
  • Static keyword defines the variable to be a class variable
  • Four access control modifiers available and they are public, private, internal and protected. These modifiers come before the static keyword.
  • Inside the class static variables can be used as regular variables. But otherwise it has to be accessed by using className.variable.
  • Inside a class a static variable and an instance variable of same names can coexist.
  • Constant is a variable with a value that do not change throughout the program
  • It is defined using the keyword const in stead of var
  • Like static variables, static methods define functionality that relate to an entire class.
  • Static methods cannot use the keyword this.
  • Static methods cannot access instance variables and instance methods of the class where it is defined. quite logical.
  • When ActionScript creates a class at runtime, it creates a method called class initializer and runs it.
  • In the class initializer it places all the static variables and all class level code that is not instance variable or instance method.
  • Every class in ActionScript is represented at runtime as an instance of the Class class.
  • Class objects are primarily used to access static properties and static methods.
  • Like other objects class objects can be used as values for assigning and return type.

Author: Ashwinee Kumar Dash.

Name of the Book: Essential ActionScript 3.0 by Colin Moock

Copyright: Creative Commons License
Disclaimer: Anything in quotation marks is a direct quotation from Essential
ActionScript 3.0
. All other notes are my own summaries of the concepts
presented in the book.

These notes are for reference purpose only and not intended to replace the book .Therefore I would strongly advise you to read the original book as well as make your own notes wherever necessary.

Send your suggestions and feedbacks to aswhineedash[at]gmail[dot]com or aswhinee2004[at]gamil[dot]com.

Classes

  • Classes are the blue prints upon which objects are built.
  • Every object that you see in a program has a class of its own.
  • Classes written from scratch known as custom classes.
  • Built in classes are used to perform some fundamental tasks
  • Classes built directly into ActionScript are known as native classes.
  • Classes are created by using class keyword. Read the rest of this entry »

I would like to thank Colin for allowing me to publish my own notes that I had jotted down while studying his (essential) book aptly titled Essential ActionScript 3.0.

EAS 3.0

In my opinion it is the best book currently available to learn Object Oriented Programming using Actionscript 3.0. The following three categories of readers can benefit from the book

  • those who are new to OOP and AS 3.0 ( they will find it most useful).
  • those wishing to upgrade from AS 2.0 to AS 3.0 will need this book to understand concepts like e4x, display architecture, Flash player security and events and event handling etc.
  • C# or C++ or java developers wishing to use AS 3.0 in their Flex projects won’t find such in depth knowledge and coverage of AS3.0 in any other book.

The importance of AS 3.0 has increased in these days due to quick adoption of Flex and to use Flex to its fullest extent one must know AS 3.0 inside out . When it comes to ActionScript, nobody teaches you the better than Colin Moock.

I, like countless others have learnt a lot about ActionScript and Flash just by reading his books. I hope he continues to write more about ActionScript, a popular language destined to become.

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