catcall

blog Type safe Eiffel (4, chapters "Generic constraints based on conformance" and "Validation with local analysis" included)

From the beginning of Eiffel the language has been characterized as strongly typed. But since its beginning there has been a hole in the type system which has not yet been fixed up to now (the so called catcall problem).


What is the hole?

The existence of the hole can be demonstrated with very simple examples.

blog Type safe Eiffel (4, chapters "Backward compatibility" and "Promiscuous generic conformance" included)

From the beginning of Eiffel the language has been characterized as strongly typed. But since its beginning there has been a hole in the type system which has not yet been fixed up to now (the so called catcall problem).


What is the hole?

The existence of the hole can be demonstrated with very simple examples.

blog Type safe Eiffel (3, chapter "Covariance" included)

From the beginning of Eiffel the language has been characterized as strongly typed. But since its beginning there has been a hole in the type system which has not yet been fixed up to now (the so called catcall problem).


What is the hole?

The existence of the hole can be demonstrated with very simple examples.

blog Type safe Eiffel (2, chapter "Feature rich ANY" included)

From the beginning of Eiffel the language has been characterized as strongly typed. But since its beginning there has been a hole in the type system which has not yet been fixed up to now (the so called catcall problem).


What is the hole?

The existence of the hole can be demonstrated with very simple examples.

blog Type safe Eiffel (1)

From the beginning of Eiffel the language has been characterized as strongly typed. But since its beginning there has been a hole in the type system which has not yet been fixed up to now (the so called catcall problem).


What is the hole?

The existence of the hole can be demonstrated with very simple examples.

blog Type safe Eiffel

The following is a short description of a solution to the catcall problem (recently posted in comp.lang.eiffel as well):


In Eiffel it is easy to generate runtime type errors. Therefore Eiffel cannot (yet) be considered to be a typesafe language.

blog catcall -- a solution

Eiffel in its current form is not completely type safe. Type errors (called catcalls in Eiffel speak) are possible. The compiler cannot detect these type errors. They usually trigger an exception at runtime.

These type errors are possible due to covariant redefinition of arguments and polymorphy. Both principles are very powerful in OO programming.

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