Overview DSL Reference

Owned by Bradley Irwin (Unlicensed)
Jan 27, 2022

High Level Constructs


unit

Units are groupings of functions and also variables.

They can be thought of as modules or namespaces. A Mezzanine script must have at least one unit.Unit must be followed with a unique unit name. Units are defined as follows.


  1. unit MyUnit;
  2. // Other code follows
  3.  
  4. string myVar;
  5.  
  6. int factorial(int x) {
  7.     if(x == 0 || x == 1) {
  8.         return 1;
  9.     } else if (x > 1) {
  10.         return factorial(x - 1);
  11.     }
  12.  
  13.     return 0;
  14. }

HEADS UP Objects, enums and validators are global, so they can optionally be in a separate source code file without a unit.

object

Indicates the start of an object declaration. Must be followed by a unique object name and attribute block


  1. object Person 
  2. {
  3.     string fname;
  4.     string sname;
  5.     int age;
  6. }

persistent

Used to indicate that an object is persistent, must precede the object definition


  1. persistent object Person
  2. {
  3.     string fname;
  4.     string sname;
  5.     int age;
  6. }

The _id attribute is also available from any persistent object. It is a uuid type.

enum

Used to declare an enumeration. Must be followed by an enumID (all caps and underscores)


 

  1. enum GENDER
  2. {
  3.     Male, Female
  4. }


validator

Used to declare a field validator

 

  1. validator FirstnameValidator 
  2. {
  3.     minlen(2); maxlen(250);
  4. }
  5. validator AgeValidator 
  6. {
  7.     minval(0);
  8. }

 

Flow control

return

Returns the value of the expression that follows from a function

 

  1. string getGreeting(string name)
  2. {
  3.     return Strings:concat("Hello, ", name);
  4. }

 

if / else

If statement

 

  1. if(name == "Tom")
  2. {
  3.     Mez:log("Hello Tom!");
  4. }
  5. else if (name == "Frank")
  6. {
  7.     Mez:log("Hello Frank!");
  8. }
  9. else
  10. {
  11.     Mez:log("Hi! Who are you?");
  12. }

 

for

For loop