Global variables

Figure 76. VarDecl

VarDecl

Variables can be declared global. Global variables are declared in the prolog.

Example 169. Global variable

  declare variable $obj := { "foo" : "bar" };
  $obj
      

Result (run with Zorba): { "foo" : "bar" }


Example 170. Global variable

  declare variable $numbers := (1, 2, 3, 4, 5);
  [ $numbers ]
      

Result (run with Zorba): [ 1, 2, 3, 4, 5 ]


You can specify a type for a variable. If the type does not match, an error is raised. Types will be explained later. In general, you do not need to worry too much about variable types except if you want to make sure that what you bind to a variable is really what you want. In most cases, the engine will take care of types for you.

Example 171. Global variable with a type

  declare variable $obj as object := { "foo" : "bar" };
  $obj
      

Result (run with Zorba): { "foo" : "bar" }


An external variable allows you to pass a value from the outside environment, which can be very useful. Each implementation can choose their own way of passing a value to an external variable. A default value for an external variable can also be supplied in case none is provided outside.

Example 172. An external global variable

  declare variable $obj external;
  $obj
      

Result (run with Zorba): An error was raised: "obj": variable has no value


Example 173. An external global variable with a default value

  declare variable $obj external := { "foo" : "bar" };
  $obj
      

Result (run with Zorba): { "foo" : "bar" }