Difference between revisions of "Literals"

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(Created page with "== Description == A literal is a notation for representing a fixed value in source code. Almost all programming languages have notations for atomic values such as integers, fl...")
 
 
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{{DISPLAYTITLE:Literals}}
 
== Description ==
 
== Description ==
 
A literal is a notation for representing a fixed value in source code. Almost all programming languages have notations for atomic values such as integers, floating-point numbers, and strings, booleans and characters.
 
A literal is a notation for representing a fixed value in source code. Almost all programming languages have notations for atomic values such as integers, floating-point numbers, and strings, booleans and characters.
  
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Literals are often used to initialize variables, for example, in the following, '1' is an IntegerLiteral which is assigned to a new created variable 'a' of data type [[Integer]]. And the three letter string in "cat" is a StringLiteral, which is assigned to a new created variable 's' of data type [[String]].
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Literals are often used to initialize variables, for example, in the following, '1' is an IntegerLiteral which is assigned to a new created variable 'a' of data type [[Core.DataTypes.SimpleDataType.Integer|Integer]]. And the three letter string in "cat" is a StringLiteral, which is assigned to a new created variable 's' of data type [[Core.DataTypes.SimpleDataType.String|String]].
  
 
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All OTX Core data types (without the Exception type) provide a literal notation term.
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==Types==
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The following types of Literals exists
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* [[Core.DataTypes.SimpleDataType|Simple Data Type]]
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* [[Core.DataTypes.ComplexDataType.ContainerDataType|Container Data Type]]
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* [[Core.DataTypes.ComplexDataType|Complex Data Type]]
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===Simple Data Type===
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The following table lists all available literals for [[Core.DataTypes.SimpleDataType|Simple Data Type]]s:
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{| {{TableHeader}}
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|- {{TableHeaderRow}}
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| '''Data Type''' || '''Literal''' || '''Sample'''
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|- {{TableRow1}}
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| '''[[Core.DataTypes.SimpleDataType.Boolean|Boolean]]''' || <tt><nowiki>{True|False}</nowiki></tt> || <tt>Boolean flag = True;</tt>
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|- {{TableRow2}}
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| '''[[Core.DataTypes.SimpleDataType.Integer|Integer]]''' || Integer number || <tt>Integer n = 1;<br/>m = n - 1234;</tt>
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|- {{TableRow1}}
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| '''[[Core.DataTypes.SimpleDataType.Float|Float]]''' || Floating-point number || <tt>Float n = 1.2;<br/>m = n + 12.345;</tt>
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|- {{TableRow2}}
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| '''[[Core.DataTypes.SimpleDataType.String|String]]''' || Quoted sequence of characters || <tt>String str = "This is a text"<br/>str = StringConcatenate(str, " definded as a literal in OTX.");</tt>
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|- {{TableRow1}}
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| '''[[Core.DataTypes.ComplexDataType.ByteField|ByteField]]''' || Sequence of bytes in hex started with a &amp; || <tt>ByteField bytes1 = &12 34 56 78 90 AB CD EF<br/>ByteField bytes2 = &1234567890ABCDE; // equals &01 23 45 67 89 0A BC DE</tt>
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|}
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===Container Data Type===
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The following table lists all available literals for [[Core.DataTypes.ComplexDataType.ContainerDataType|Container Data Type]]s:
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{| {{TableHeader}}
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|- {{TableHeaderRow}}
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| '''Data Type''' || '''Literal''' || '''Sample'''
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|- {{TableRow2}}
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| '''[[Core.DataTypes.ComplexDataType.ContainerDataType.List|List]]''' || List one or more elements in braces seperated with comma || <tt><nowiki>List<Integer> integerList = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };</nowiki><br/><nowiki>List<List<String>> stringList = { { "Text11", "Text12" }, { "Text21", "Text22", "Text23" }, { "Text31" } };</nowiki></tt>
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|- {{TableRow1}}
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| '''[[Core.DataTypes.ComplexDataType.ContainerDataType.Map|Map]]''' || List one or more key value pairs in braces seperated with comma; in each pair of key value, the key connects with the value by the equal sign || <tt><nowiki>Map<String, Integer> myMap1 = { "Key1"=1234, "Key2"=567, "Key3"=89 };</nowiki><br/><nowiki>Map<String, List<Integer>> myMap2 = { "Key1"={ 1, 2, 3, 4 }, "Key2"={ 5, 6, 7 }, "Key3"={ 8, 9 } };</nowiki></tt>
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|}
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===Complex Data Type===
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Literals for [[Core.DataTypes.ComplexDataType|Complex Data Type]] have the following syntax:
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<syntaxhighlight lang="java" enclose="div" style="font-size: medium;">
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@DataTypeName:MemberValue1/MemberValue2/../MemberValueN
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</syntaxhighlight>
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Where '''DataTypeName''' is the name of the related data type and '''MemberValue''' the value of the corresponding value. Sample:
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<syntaxhighlight lang="java" enclose="div" style="font-size: medium;">
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// ResultStateLiteral for enumeration value POSITIVE
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@ResultState:POSITIVE;
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// UserExceptionLiteral to throw an user defined exception
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@UserException:"FATAL_ERROR"/"There is a fatal error occured!";
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// QuantityLiteral for a value of 1.2 %
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@Quantity:1.2/"%"/1;
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</syntaxhighlight>

Latest revision as of 08:28, 12 July 2017

Description

A literal is a notation for representing a fixed value in source code. Almost all programming languages have notations for atomic values such as integers, floating-point numbers, and strings, booleans and characters.

Literals are often used to initialize variables, for example, in the following, '1' is an IntegerLiteral which is assigned to a new created variable 'a' of data type Integer. And the three letter string in "cat" is a StringLiteral, which is assigned to a new created variable 's' of data type String. 

Integer a = 1;
String s = "cat";

Types

The following types of Literals exists

Simple Data Type

The following table lists all available literals for Simple Data Types:

Data Type Literal Sample
Boolean {True|False} Boolean flag = True;
Integer Integer number Integer n = 1;
m = n - 1234;
Float Floating-point number Float n = 1.2;
m = n + 12.345;
String Quoted sequence of characters String str = "This is a text"
str = StringConcatenate(str, " definded as a literal in OTX.");
ByteField Sequence of bytes in hex started with a & ByteField bytes1 = &12 34 56 78 90 AB CD EF
ByteField bytes2 = &1234567890ABCDE; // equals &01 23 45 67 89 0A BC DE

Container Data Type

The following table lists all available literals for Container Data Types:

Data Type Literal Sample
List List one or more elements in braces seperated with comma List<Integer> integerList = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
List<List<String>> stringList = { { "Text11", "Text12" }, { "Text21", "Text22", "Text23" }, { "Text31" } };
Map List one or more key value pairs in braces seperated with comma; in each pair of key value, the key connects with the value by the equal sign Map<String, Integer> myMap1 = { "Key1"=1234, "Key2"=567, "Key3"=89 };
Map<String, List<Integer>> myMap2 = { "Key1"={ 1, 2, 3, 4 }, "Key2"={ 5, 6, 7 }, "Key3"={ 8, 9 } };

Complex Data Type

Literals for Complex Data Type have the following syntax: 

@DataTypeName:MemberValue1/MemberValue2/../MemberValueN

Where DataTypeName is the name of the related data type and MemberValue the value of the corresponding value. Sample: 

// ResultStateLiteral for enumeration value POSITIVE
@ResultState:POSITIVE;

// UserExceptionLiteral to throw an user defined exception
@UserException:"FATAL_ERROR"/"There is a fatal error occured!";

// QuantityLiteral for a value of 1.2 %
@Quantity:1.2/"%"/1;
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