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Entity Selection Statements

 

Statements

 

    EntitySelection

    Selection

    NullSelection

 

 

General

 

The EntitySelection statement may be a pattern statement.

 

Objects of the same entity are not naturally related to each other since each entity must be regarded as enclosing a pool of objects. The objects in the pool may be explicitly ordered by the analyst specifying relationships such as "Next" or "Succeeds".

 

The EntitySelection statement selects objects from the pool in a random order. However, objects are returned in creation order (currently) but this cannot be relied upon and will certainly vary from Model Compiler to Model Compiler.

 

 

EntitySelection Statement

 

EntitySelection:Customer

Selection

...

NullSelection

...

 

The EntitySelection statement selects all the objects of an entity in an order which is nondeterministic.

 

This statement can be placed anywhere (in "One" or "Many" contexts) as it creates its own entity context.

 

 

Selection Statement

 

EntitySelection:Customer

Selection

...

 

This statement allows all objects in the specified entity to be selected and processed in the subregion. If the subregion is executed, there will always be at least one object to process.  The new context is that of the selection entity.

 

 

NullSelection Statement

 

EntitySelection:Customer

NullSelection

...

 

The action statements in the NullSelection subregion are executed if the entity has no objects. The context is identical to that before the EntitySelection statement but the context is known as the null context.

 

 

EnitySelection Example

 

EntitySelection:Customer

Selection

|

| many context from EntitySelection

|

NullSelection

|

| single null context

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