[en] This paper shows that one can reason at a meta level about the structure of object-oriented source code in a language-independent way. To achieve this, we propose a language-independent meta-level interface to extract complex information about the structure of the source code. This approach is validated by defining a set of logic queries to detect object-oriented best practice patterns and design patterns in two different languages: Smalltalk and Java. The queries were applied to two similar medium-sized applications available for each language, and the results were confirmed by manually investigating the source code and available documentation.