`setAs()` has no definition for class `Spatial`

[etiennebr]

When sourcing sp.R which contains setAs("Spatial", "sf", ...), setAs("Spatial", "sfc", ...), setAs("sf", "Spatial", ...) and setAs("sfc", "Spatial", ...).

in method for ‘coerce’ with signature ‘"Spatial","sf"’: no definition for class “Spatial”
in method for ‘coerce’ with signature ‘"Spatial","sfc"’: no definition for class “Spatial”
in method for ‘coerce’ with signature ‘"sf","Spatial"’: no definition for class “Spatial”
in method for ‘coerce’ with signature ‘"sfc","Spatial"’: no definition for class “Spatial”

It complains on devtools::load_all(".") and devtools::document(roclets=c('rd', 'collate', 'namespace')), which both source these functions (well, all .R files).

[edzer]

These are messages, not warnings or NOTE's, so we can safely ignore them. I'd also like them to go away, but not at the cost of having to import sp without a good reason.

[etiennebr]

Yes, this is not a good reason to depend on sp. I was wondering if you or someone knew a way to attach the namespace only when the package is there. I'm not aware of one, and couldn't find one quickly, but I'd be surprised if sfwas the first to face this.