Derived types

A Fortran derived type (defined using a TYPE statement) is like a .NET object in some respects, but with important differences. In particular, a Fortran derived type can contain Fortran arrays or pointers to arrays. You can also have Fortran arrays whose elements are of a derived type.

As an extension to standard Fortran, FTN95 allows you to include an OBJECT (i.e. a Fortran pointer to a .NET object) as a component of a derived type with the following restrictions.

1. Variables that are based on derived types cannot be guaranteed to be scanned during garbage collection . For this reason, any derived type that includes an OBJECT is subject to the same restrictions as OBJECTs themselves. Thus, when automatic garbage collection is required to avoid memory leakage, variables of these derived types must be local to a routine or be stored in a module (for a global array you can use a .NET array instead).

2. Furthermore, a derived type that includes an OBJECT cannot include a Fortran array (or a pointer to a Fortran array) at the same time. This is because a derived type containing one or more OBJECT declarations is effectively a .NET object.



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