Using Caché Globals - InterSystems Documentation

Using Multidimensional Storage (Globals)3.10 Using Indirection with GlobalsBy means of indirection, Caché ObjectScript provides a way to create global references at runtime.This can be useful in applications where you do not know global structure or names at program compilationtime.Indirection is supported via the indirection operator, @, which de-references a string containing anexpression. There are several types of indirection, based on how the @ operator is used.The following code provides an example of name indirection in which the @ operator is used to dereferencea string containing a global reference:// Erase any existing dataKill ^Data// Set var to an global reference expressionSet var = "^Data(100)"// Now use indirection to set ^Data(100)Set @var = "This data was set indirectly."// Now display the value directly:Write "Value: ",^Data(100)You can also use subscript indirection to mix expressions (variables or literal values) within indirectstatements:// Erase any existing dataKill ^Data// Set var to a subscript valueSet glvn = "^Data"// Now use indirection to set ^Data(1) to ^Data(10)For i = 1:1:10 {Set @glvn@(i) = "This data was set indirectly."}// Now display the values directly:Set key = $Order(^Data(""))While (key '= "") {Write "Value ",key, ": ", ^Data(key),!Set key = $Order(^Data(key))}Indirection is a fundamental feature of Caché ObjectScript; it is not limited to global references. Formore information, refer to the “Indirection” section in the “Operators” chapter of Using CachéObjectScript. Indirection is less efficient than direct access, so you should use it judiciously.28 Using Caché Globals