Eiffel for .NET Compliance

As of Eiffel for ASP.NET 5.6 and EiffelStudio 5.7; Eiffel for .NET introduces the notion of Eiffel-Compliance. .NET specifies a number of language interoperability rules in a Common Language Specification-Compliance specification. Eiffel for .NET supports all CLS-Compliant type and features in .NET but now additionally supports a number of non-CLS-compliant types and features. This is the purpose of the Eiffel-Compliant notion.

The information contained within this page does not go into any depth on the Common Language Specification (CLS) or CLS-Compliance. For this information please see Microsoft's on-line documentation What is the Common Language Specification?


The CLS states a number of rules .NET tools have to abide by to be CLS-compliant. These rules relate to both a .NET producer, generally a compiler generating .NET code, and a consumer, which is generally a compiler that consumes .NET assemblies for reuse. Eiffel-Compliance relates only to consumption of .NET assemblies.

What is Eiffel-Compliant?

As already stated, anything CLS-compliant is Eiffel-compliant. Eiffel-Compliancy merely allows for exceptions so that non-CLS-compliant assemblies, types and members can be used in Eiffel for .NET.

The following list outlines the supported non-CLS-compliant types:

  • All unsigned numerical basic types such as System.UInt32 as System.UInt64, represented by NATURAL_xx.
  • Native pointers (System.IntPtr), represented by POINTER

Typically assemblies, types or members are marked with the System.CLSCompliantAttribute attribute to explicitly indicate if they are CLS-compliant or not. The Eiffel for .NET compiler will now ignore this attribute and instead infer if they are Eiffel-Compliant. With such an inference engine at hand, Eiffel for .NET opens itself up to extended support for COM/Legacy interop as well support assemblies not adhering to CLS-compliant rules, for one reason or another.