Jared Deckard

I might try to dig into a perf dump and see where the time is going. That seems like a lot of time to just be caused by an extra...

I ran [the benchmarks above](https://gist.github.com/sloria/2e0b141b3d05fe0dafbdeafd294ebae8) using python 3.7.2 against the `dev` branch. I had to make a copy of `Schema` to get sane `cProfile` output, because recursion merges calls into...

#1304 makes `dump()` ~18% faster for both paths. #1306 makes `dump()` ~21% faster for `List(Nested)`, which makes the two paths run in effectively the same amount of time (< 1%).

Ya, `load()`has the same ~35% slowdown when comparing `List(Nested)` to `Nested(many)`. The same strategy should work there. **Edit:** I added the fix for `load()` in #1306 and confirmed that it...

This is effectively polymorphism, but with multiple inheritance. AFAIK none of the community polymorphism libraries handle this use case. If I were in this situation I would want to declare...

It was removed intentionally from v3 for #430. It looks like it didn't get documented, probably because the behavior was a regression that also wasn't documented. I believe the reason...

I suspect paths might be too obscure of a type to include fields for it in marshmallow's core. I would recommend publishing any packages you create on pypi then making...

I'm not saying `pathlib` is obscure, rather that using a system path as a schema field is. Custom field types should be convenient enough to allow users to wrap obscure...

I dug into the issues to see if I could find any similar requests for new fields and ran across https://github.com/marshmallow-code/marshmallow/pull/1735. It is also a part of the standard library...

I would recommend separate field types for validating the mutually exclusive attributes. ```py class Path(Field) class Directory(Path) class File(Path) ``` Using constructor args for optional validation is convenient, but providing...