FOR operator

The FOR operator creates an action that implements loop.

Syntax

FOR expression [ORDER [DESC] orderExpr1, ..., orderExprN]
[NEW [alias =] className]
DO action
[ELSE alternativeAction]

It is possible to include a NEW block in the operator but not to specify a condition (considered equal to TRUE); in this case, the syntax is as follows:

NEW [alias =] className
action

Description

The FOR operator creates an action that implements loop. This operator must add its local parameters when defining a condition. These parameters correspond to the objects being iterated and are not parameters of the created action. You can also use a NEW block to specify the name of the class of the object that will be created for each object collection that meets the condition. The name of this object needs to be specified. This name will be used as the name of the local parameter that the created object will be written to.

The object iteration order in the FOR operator can be specified with an ORDER block. If a new parameter is declared in the expressions that define the order (meaning that the parameter not met earlier in the FOR option or in the upper context), the condition of all these expressions being non- NULL is automatically added.

The main action is specified after the keyword DO; an alternative may be specified after the keyword ELSE.

In the case when the operator contains a NEW block, and no condition is specified, the main action will be called for the created object.

Parameters

• expression

  Expression defining a condition. In this expression, you can both access already declared parameters and declare new local parameters.

• DESC

  Keyword. Specifies a reverse iteration order for object collections.

• orderExpr1, ..., orderExprK

  A list of expressions that define the order in which object collections will be iterated over. To determine the order, first the value of the first expression is used; then, if equal, the value of the second is used, etc. If the list is undefined, iteration is performed in an arbitrary order.

• alias

  The name of the local parameter that will correspond to the object being created. Simple ID.

• className

  The name of the class of the object to create. Defined by a class ID.

• action

  Context-dependent action operator describing the main action.

• alternativeAction

  Context-dependent action operator defining an alternative action. Parameters added when defining the condition/creating the object cannot be used as parameters of this action.

Examples

name = DATA STRING[100] (Store);

testFor  {
    LOCAL sum = INTEGER ();
    FOR iterate(i, 1, 100) DO {
        sum() <- sum() (+) i;
    }

    FOR in(Sku s) DO {
        MESSAGE 'Sku ' + id(s) + ' was selected';
    }

    FOR Store st IS Store DO { // iterating over all objects of the Store class
        FOR in(st, Sku s) DO { // iterating over all Sku for which in is set
            MESSAGE 'There is Sku ' + id(s) + ' in store ' + name(st);
        }

    }
}

newSku ()  {
    NEW s = Sku {
        id(s) <- 425;
        name(s) <- 'New Sku';
    }
}

copy (Sku old)  {
    NEW new = Sku {
        id(new) <- id(old);
        name(new) <- name(old);
    }
}

createDetails (Order o)  {
    FOR in(Sku s) NEW d = OrderDetail DO {
        order(d) <- o;
        sku(d) <- s;
    }
}