Proposal: glue notation in req_url_path(_append)

[jonthegeek]

req_template() supports glue syntax, but loses the composability of request() |> req_url_path_append(). But paths are often also documented with glue-like syntax. For example, the apis.guru api has a /{provider}.json path, where provider is a path parameter (and the OpenAPI spec specifically allows such path parameters).

At first I thought this would need a new function, but in theory req_url_path() and req_url_path_append() could treat named arguments as path parameters, making these equivalent:

request("https://api.apis.guru/v2") %>% 
  req_url_path_append("googleapis.com.json")

request("https://api.apis.guru/v2") %>% 
  req_url_path_append("{provider}.json", provider = "googleapis.com")

It looks like only dots_to_path would need to be updated, and the tests look robust enough that it could be done safely, I think. I could probably whip up a PR if this sounds reasonable.

[jennybc]

gh has some code related to this, which came in r-lib/gh#121.