To conditionally install the swag command required for my
openapi-generate target, I find this approach to be both easy and
portable. It works well because swag is a Go binary, so I have a way
to install it regardless of the user's platform, using go install:
GOPATH ?= $(HOME)/go/bin
SWAG = $(GOPATH)/swag
openapi-generate:
test -x $(SWAG) || go install github.com/swaggo/swag/cmd/swag
$(SWAG) init
$(SWAG) fmt
It's important to note, the variables must be set outside the
target, openapi-generate.
