capri, a script language

Value types

Types are dynamically assigned to variables; you can not specify a type for a variable. Any variable can contain one of the following types of value:

• object

  An object has fields that can be assigned any type of value. You create an object like this:

  myObject = object();

  This creates an empty object. You can set/get fields of the object using:

  myObject.someField = 1337;
  myObject["anotherField"] = "This is cool!";

• array

  An array is an actual array in memory that is used when you need plain data for native calls. You can create an array like this:

  myArray = array<8>(128);

  This creates an 8-bit array with a length of 128. You can access each field of the array using the array subscript [] operator:

  myArray[0] = 25;
  someNumber = myArray[0] * 2;

  Accessing a cell of an array on results in a number. Only numbers can be assigned to array cells.

• bool

  is either true or false. Equality (==, !=), logical (&&, ||) and relational (>, <, >=, <=) expressions result in a value of type bool.

• number

  a numeric literal can be denoted in the following ways:

  25           // integer value
  43.210       // decimal value
  0xDEADBEEF   // hexadecimal value
  0b10010110   // binary value

• string

  string literals are denoted using quotes " or primes '. See the strings page for more details.

• concurrent_id

  using a concurrent expression results in a value of this type. This type of value is used for the join expression to retrieve the value of a concurrently executed statement.

• environment

  when an variable name starts with a dollar $ sign, a special handling is done. Accessing the value of such a variable returns the value of the environment variable (retrieved via the getenv function) with that name.

  Like this you can easily retrieve values from the environment:

  compiler = $CXX;
  IO.println("The compiler is '{compiler}'");

  Setting such a variable is equal to a call to the putenv C function (or SetEnvironmentVariable on Windows).

• project

  a variable can be assigned a project. When declaring a project with a name, there is actually a variable in the global scope with that name which holds the project value.

• task

  a variable can be assigned a task. When declaring a task with a name, there is a variable in the declaration scope with that name which holds the task value.

  task someTask { /* ... */ }
  // the variable "someTask" now contains the task value:
  someTask();
  // assigning the variable copies the reference to the task:
  myVariable = someTask;
  myVariable();

• null

Type checking

To check if an object is of one of the types, use the typecheck expression. This expression looks returns either true or false. On the left-hand-side there can be any expression, on the right-hand-side one of the above types.

something = object();
if(something is object) {
	IO.println("It's an object!");
}