Akim Demaille wrote: > Le 22 sept. 2012 à 17:02, Jim Meyering a écrit : > >> How about something like this? >> >> release-type = >> \ >> $(subst :, , >> \ >> $(if $(RELEASE_TYPE), \ >> $(or $(findstring :$(RELEASE_TYPE):,:alpha:beta:stable:), >> \ >> $(error invalid RELEASE_TYPE: $(RELEASE_TYPE))), \ >> $(error RELEASE_TYPE undefined))) >> >> That's not quite right because it fails to reject RELEASE_TYPE=alpha:beta. >> Adding one more "if" just for that case should do the job: >> >> release-type = >> \ >> $(subst :, , >> \ >> $(if $(RELEASE_TYPE), \ >> $(if $(findstring :,$(RELEASE_TYPE)), \ >> $(error invalid RELEASE_TYPE: $(RELEASE_TYPE)), \ >> $(or $(findstring :$(RELEASE_TYPE):,:alpha:beta:stable:), \ >> $(error invalid RELEASE_TYPE: $(RELEASE_TYPE)))), \ >> $(error RELEASE_TYPE undefined))) > > Nice! Further improvement: use " " instead of > ":" as separator, as it is a more natural separator in Make, > which removes the need to add and strip these ":", and you > get something which is more generic: > > _null := # Null character. > _sp := $(_null) # White space. > > RELEASE_TYPES = alpha beta stable > > # member-check VARIABLE,VALID-VALUES > member-check = \ > $(if $($(1)), \ > $(if $(findstring $(_sp),$($(1))), \ > $(error invalid $(1): '$($(1))', expected $(2)), \ > $(or $(findstring $(_sp)$($(1))$(_sp),$(_sp)$(2)(_sp)), \ > $(error invalid $(1): '$($(1))', expected $(2)))), \ > $(error $(1) undefined)) > > $(call member-check,RELEASE_TYPE,$(RELEASE_TYPES))
I like the function. For this application, where no valid value contains a space, your use of SPACE as a delimiter is fine. However, in general you might want to use a byte that is less likely to be included in one of the expected values. > I couldn't find a means to factor elegantly the checks to > have a single $(error invalid $(1)). I tried too. Oh well.
