Category:Elena: Difference between revisions
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ELENA is a general-purpose, object-oriented, polymorphic language with late binding. It features message dispatching/manipulation, dynamic object mutation, a script engine / interpreter and mix-ins. |
ELENA is a general-purpose, object-oriented, polymorphic language with late binding. It features message dispatching/manipulation, dynamic object mutation, a script engine / interpreter and mix-ins. |
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The simplest program |
== The simplest program == |
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== |
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To create a simple console program we have to declare the **program** symbol in the project root namespace: |
To create a simple console program we have to declare the **program** symbol in the project root namespace: |
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**Console::write** method is similar to **writeLine** except that it writes to the output screen without a new line character. |
**Console::write** method is similar to **writeLine** except that it writes to the output screen without a new line character. |
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Declaring a variable |
== Declaring a variable == |
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=== |
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A variable can be declared in an assignment statement starting with **var** attribute: |
A variable can be declared in an assignment statement starting with **var** attribute: |
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system'startUp(5) |
system'startUp(5) |
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Basic Types |
== Basic Types == |
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=== |
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The Boolean Type |
=== The Boolean Type === |
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===== |
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Boolean type is used in conditional operations and may accept only two Boolean literals - **true** and **false**. |
Boolean type is used in conditional operations and may accept only two Boolean literals - **true** and **false**. |
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false==true is false |
false==true is false |
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=== The Numeric types === |
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The most used numeric types in ELENA are 32-bit signed integer number (represented by **IntNumber**), 64-bit signed integer number (represented by **LongNumber**) and 64-bit floating-point number (represented by **RealNumber**): |
The most used numeric types in ELENA are 32-bit signed integer number (represented by **IntNumber**), 64-bit signed integer number (represented by **LongNumber**) and 64-bit floating-point number (represented by **RealNumber**): |
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Real number - 2.3456 |
Real number - 2.3456 |
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=== The string Type === |
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**LiteralValue** is used to store the text encoded in UTF-8. LiteralValus is read-only collection of **CharValue** classes each representing UTF-32 symbol. *Note that one character may be encoded with more than one byte!*. |
**LiteralValue** is used to store the text encoded in UTF-8. LiteralValus is read-only collection of **CharValue** classes each representing UTF-32 symbol. *Note that one character may be encoded with more than one byte!*. |
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The last character of Привет is т |
The last character of Привет is т |
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=== Array type === |
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It is possible to declare a dynamic or static array. |
It is possible to declare a dynamic or static array. |
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dynamic array 1,b,2.3 |
dynamic array 1,b,2.3 |
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== Basic arithmetic operations == |
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ELENA supports basic arithmetic operations with integer and floating-point numbers: |
ELENA supports basic arithmetic operations with integer and floating-point numbers: |
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12 + 5 * 2.3 = 23.5 |
12 + 5 * 2.3 = 23.5 |
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== Conditions, Multi-select, Loops == |
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Conditional statement in ELENA are defined as follows: |
Conditional statement in ELENA are defined as follows: |
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]. |
]. |
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== Classes, Fields Methods, Constructors == |
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Everything in ELENA is a class. So to implement some tasks we will have to declare our own classes. |
Everything in ELENA is a class. So to implement some tasks we will have to declare our own classes. |
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=== Declaring a simple class === |
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Let's create a simple class : |
Let's create a simple class : |
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*Note that in ELENA a class is an object itself and can be used by like any other object* |
*Note that in ELENA a class is an object itself and can be used by like any other object* |
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=== Class Inheritance === |
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We may inherit our class. When the parent is not explicitly declared - the class inherits *system'Object* super class |
We may inherit our class. When the parent is not explicitly declared - the class inherits *system'Object* super class |
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I'm a Child Class. |
I'm a Child Class. |
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=== Private methods === |
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It is possible to declare the private methods which cannot be called outside the class. |
It is possible to declare the private methods which cannot be called outside the class. |
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system'startUp(5) |
system'startUp(5) |
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=== Properties === |
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In normal case the class fields cannot be accessed outside the class. That's why we may declare a special method to access it: |
In normal case the class fields cannot be accessed outside the class. That's why we may declare a special method to access it: |
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]. |
]. |
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== Exception Handling == |
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We may use try-catch statement to handle the possible exceptions: |
We may use try-catch statement to handle the possible exceptions: |
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