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各位高手,
分析以下,
android product.mk中有一段,
define check-all-products
$(if ,, \
$(eval _cap_names :=) \
$(foreach p,$(PRODUCTS), \
$(eval pn := $(strip $(PRODUCTS.$(p).PRODUCT_NAME))) \
$(if $(pn),,$(error $(p): PRODUCT_NAME must be defined.)) \
$(if $(filter $(pn),$(_cap_names)), \
$(error $(p): PRODUCT_NAME must be unique; "$(pn)" already used by $(strip \
$(foreach \
pp,$(PRODUCTS),
$(if $(filter $(pn),$(PRODUCTS.$(pp).PRODUCT_NAME)), \
$(pp) \
))) \
) \
) \
$(eval _cap_names += $(pn)) \
$(if $(call is-c-identifier,$(pn)),, \
$(error $(p): PRODUCT_NAME must be a valid C identifier, not "$(pn)") \
) \
$(eval pb := $(strip $(PRODUCTS.$(p).PRODUCT_BRAND))) \
$(if $(pb),,$(error $(p): PRODUCT_BRAND must be defined.)) \
$(foreach cf,$(strip $(PRODUCTS.$(p).PRODUCT_COPY_FILES)), \
$(if $(filter 2,$(words $(subst :,$(space),$(cf)))),, \
$(error $(p): malformed COPY_FILE "$(cf)") \
) \
) \
) \
)
endef
在这个里面,$(PRODUCTS.$(p).PRODUCT_NAME),这个里面的点号是什么意思,将这3个变量连在一起表示什么意思,
还有$(if ,, \中的两个逗号表示什么意思 |
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