The syntax of path variables is ambiguous about aspen.py

[Changaco]

Alternatively we could drop support for typecasting, it's seldom used AFAIK, and the current implementation is inefficient.

[chadwhitacre]

Without typecasting you have to do the typecasting manually in each simplate. This gets verbose and WET.

/foo/%bar_id.bar/baz.spt
/foo/%bar_id.bar/buz.spt
/foo/%bar_id.bar/biz.spt

Inside each simplate I want a bar object without having to manually call a library function.

Option: typecasters only apply to directory parts, not file parts? Would that work?

[Changaco]

In Liberapay we don't use typecasting to handle the /%username/ path segment, we import and call the get_participant function in every simplate. Calling the function explicitly makes it easier to send extra arguments to it. The extra import is a little redundant, but it could be removed by attaching get_participant to the website object. This leads me to the conclusion that builtin support for typecasters is unnecessary.

I think the default typecasters (int and float) could be advantageously replaced by simple helper methods that would be available for both the path and the querystring:

bar_id = request.path.get_int('bar_id', minimum=1)
x = request.path.parse('x', float)
page = request.qs.get_int('page', default=1)

[chadwhitacre]

If you want to remove typecasting I won't object. If I ever get to build another Aspen/Pando site and I want typecasters I can bring it back locally as a state chain function. ☺️