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This topic provides an overview of the basic elements of the Simple Issue Language (SIL) scripting syntax. |
Complex data types
Arrays
Arrays are created by adding []
after any basic type. The following list represents valid arrays:
string[]
boolean[]
number[][]
integer[]
date[][][]
interval[]
You can also create arrays for a user-defined structure:
Person[][]
Key-value arrays
Arrays in SIL where positions in the list act as keys. Key-value arrays (or maps) are declared like regular arrays.
Learn more about using the indexing operator to create key-value maps and retrieve values from them.
Structures
Structures are user-defined data types. A structure in SIL is like a container that can hold different types of data together. The syntax for defining a structure is:
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struct StructureName { type1 field1; type2 field2; // ... more fields } |
The type of each field can be a basic data type, a user-defined structure, a self-referential structure, or arrays of these types. The following examples show how to define a structure with each type:
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struct Address { string street; string city; string zipCode; //Basic data types in structure } struct Employee { string id; string name; Address workAddress; // Structure inside structure Address homeAddress; // Can use same type multiple times } struct Department { string name; Department parent; // A Department can reference itself Department[] subDepartments; // Can have array of same type } |
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Best practices when creating structures:
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To access the value of a field from a variable in a structure, use the syntax:
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<varName>.<fieldName> |
You can initialize structures field-by-field:
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Employee emp; emp.id = "E123"; emp.name = "John Doe"; emp.workAddress.street = "123 Work St"; emp.workAddress.city = "Work City"; |
Alternatively, you can do a one-line initialization, including nested initialization:
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struct Point { integer x; integer y; } Point p = {10, 20}; // Initialize all fields at once struct PersonInfo { string name; number salary; Point location; } PersonInfo person = {"John Doe", 50000.00, {10, 20}}; // Nested initialization |
Literals
Literals are fixed values that appear directly in the code. In SIL, literals are used to represent constant values of different data types.
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Literals refer to the constant values used in scripts, NOT the use of a constant which is the readonly attribute of variables. |
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Basic type literals |
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String, Date, and Interval literals | These types require double quotes (" ").
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Array literals | Arrays use curly braces and commas:
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Special literals | You can use
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Variables
Variables are named containers that use the data types. They are like labeled boxes that can hold specific values.
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// Variable format: <data type> <variable name> // Variable declaration: string name; // A container that can hold text number pi; // A container that can hold decimal numbers //You can also have an array of the type of variable# { variable1, variable2, variable3 }. // where variable# can also be an array |
You can create an array from variables as illustrated in the following example:
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// First, declare some variables string name1 = "John"; string name2 = "Jane"; string name3 = "Bob"; // Create an array from these variables string[] names = {name1, name2, name3}; // Result: names = {"John", "Jane", "Bob"} |
You can also create array variables:
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// First, declare some array variables string[] teamA = {"John", "Jane"}; string[] teamB = {"Bob", "Alice"}; string[] teamC = {"Charlie", "David"}; // Create an array of arrays from these variables string[][] allTeams = {teamA, teamB, teamC}; // Result: allTeams = { // {"John", "Jane"}, // {"Bob", "Alice"}, // {"Charlie", "David"} // } |
Variable declaration and initialization
To give value to your variables, you initialize them either when you declare them or later.
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string employeeName; // Just declaring employeeName = "John"; // Initializing after declaration string employeeAge = 25; // Declare and initialize at once // More examples of variable declaration integer random = 2; number pi = 3.14; boolean valid; date today = currentDate(); interval spent = "1h 30m"; interval estimate = "2d" - spent; number [][] matrix = {{0,1}, {2,3}, {4,5}}; |
Constants
Variables can be made readonly by adding the keyword const
before the data type when the variable is first defined.
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const string COMMA = ","; const number PI = 3.14; |
If set to an array or structure, the readonly attribute will be applied to all the elements of the array or all fields of the structure.
Explicit type casting
When types are compatible, SIL automatically converts one type to another. Automatic conversion can lead to ambiguous results. If you want to tell SIL how to convert a type, use explicit type casting with the following syntax:
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(<target_type>)varname |
The following example illustrates how explicit type casting returns accurate results:
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integer n = 1; number x = 3.14; string s = "2"; //Ambiguous - could mean different things: return n + s; // SIL doesn't know if you want "12" or 3 //Explicit - clearn intentions: return (string)n + s; // Forces n to be treated as string "1" - clearly wants a string "12" return n + (number)s; // Forces s to be treated as number 2 - clearly wants a number (3) |
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Note: Not all type casts are valid. Converting an interval to a date or a date to a string is an example of invalid type casting. |
User-defined functions
SIL comes with many out-of-the-box functions by SIL, but allows you to define local functions, referred to as user-defined routines (UDRs). To define and declare a function, use this general syntax:
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function <name>(<type> param1, <type> param2, ...) { Instruction1; ... InstructionN; return <value>; } |
For additional details, check the User-defined routines (UDRs) topic.