port versus path dependency declaration

[Renee Otten]

I am trying to understand why in some Python ports the run dependencies are declared using path instead of port statements - is there an advantage/preference for one over the other?

For example, in the py-spyder-devel Portfile (but also the py-autopep8, which I recently updated) it uses: "depends_lib-append path:${python.pkgd}/pep8:py${python.version}-pep8”, which I changed to "depends_lib-append path:${python.pkgd}/pycodestyle:py${python.version}-codestyle” in the py-autopep8 Portfile. 

If I understand it correctly form the guide the path statement will look if a specific file is present, if not it will install the port. So, in this case for  pep8/pycodestyle in ${frameworks_dir}/Python.framework/Versions/${python.branch}//lib/python${python.branch} ; that file is present but with the extension .py - is that implicitly assumed or should one provide the extension in the path specification. Also, is there any advantage here of using path instead of just doing: "depends_lib-append port:py${python.version}-pep8” or "depends_lib-append port:py${python.version}-pycodestyle”?