Feel free (encouraged even) to open issues and make PRs.
As well as the usual all the publicly facing methods having docstrings, most of the internal methods do also. You can view them in the source; or via the julia REPL etc. Hopefully the internal docstrings make it clear how each method is used.
The primary point of extension for DataDeps.jl is in developers defining their own DataDep types. 99% of developers won't need to do this, a
ManualDataDep or a normal (automatic)
DataDep covers most use cases. However, if for example you want to have a DataDep that after the download is complete and after the
post_fetch_method is run, does an additional validation, or some data synthesis step that requires working with multiple of the files simultaneously (which
post_fetch_method can not do), or a
SemiManualDataDep where the user does some things and then other things happen automatically, then this can be done by creating your own
The code for
ManualDataDep is a good place to start looking to see how that is done. You can also encapsulate an
DataDep as one of the elements of your new type.
If you do this you might like to contribute the type back up to this repository, so others can use it also. Particularly, if it is something that generalises beyond your specific use case.