Should DEPENDS_ON cardinality between Module and ExternalModule include ExternalDeclarations?

[JohT]

Hey 👋,

i've recognized that ExternalDeclaration cardinality isn't included in the sum of cardinalities of the DEPENDS_ON relationship between a Module and an ExternalModule. Everything else that Module declares or depends on seems to be included as i'd expect.

Here is a picture of an example from the analysis of ts-output-react-router.json with the example-query.cypher:

• DEPENDS_ON relationships are displayed with their cardinalities
• The orange ìndex.ts node is the Module
• The grey history.ts node is the ExternalModule
• The blue and green nodes are elemens that are declared by Module and depend on ExternalModule. Their cardinalities sum up to 4 which equals the cardinality between Module and ExternalModule.
• The purple nodes are labeled ExternalDeclaration. They are exported by the ExternalModule and used within the ExternalModule. Their cardinalities (2x2=4) between Module and ExternalDeclaration are not included in the sum of cardinalities between Module and ExternalModule.

To rephrase that in cypher language 😀:

• module_rel.cardinality of (source:TS:Module)-[module_rel:DEPENDS_ON]->(target:TS:ExternalModule) contains the sum of cardinalities between those modules
• The sum above contains all element_rel.cardinality of (source)-[:DECLARES]->(element)-[element_rel:DEPENDS_ON]->(target)
• The sum above does not contain declaration_rel.cardinality of (source)-[declaration_rel:DEPENDS_ON]->(declaration:ExternalDeclaration)<-[:EXPORTS]-(target)

What is reason for leaving out external declaration dependencies between modules or is this unintentional?

Thank you very much 🙏,
Johannes

By the way: Awesome plugin for Typescript 👍. I'm trying to integrate it into my code-graph-analysis-pipeline.

[SebastianWendorf]

Hi, thanks for bringing this up! The behavior you observed is intentional.
The "original" dependencies that got detected in the code are the ones between the module declarations and the external declarations. These dependencies are then propagated on both sides. This means if a declaration depends on an external declaration, it also depends on the external module (with the same cardinality). Similarly does the declaring module depend on the external declarations (using the aggregated cardinalities of all declarations). Finally these dependencies are then aggregated, forming a dependency between the declaring module and the external module.
Effectively, this gives us different views on the same 4 dependencies that exist in your code.

Here is an example roughly outlining how dependencies are aggregated in the graph:
Dependency Example.drawio.pdf

I will adjust the documentation to better reflect this behavior.

[JohT]

Hi @SebastianWendorf,

awesome. Now this is much clearer for me. Thanks a lot 🙏. I'll close this issue.