问题描述
在我的Makefile中，我想检查以下复杂情况:
ifdef VAR1 || VAR2 || VAR3
action
endif
但是文档中说不支持类似的语法.因此，我想到的唯一简单的解决方法是使用串联:
ifneq ($(VAR1)$(VAR2)$(VAR3),)
action
endif
还有其他更正确的解决方案吗?
在以下情况下:
ifdef VAR1 && VAR2 && VAR3
action
endif
需要写
ifdef VAR1
ifdef VAR2
ifdef VAR3
action
endif
endif
endif
这也很难看.还有更优雅的选择吗?
如果您的make是GNU-make，并且所有已定义的变量都包含非空格字符，
ifdef VAR1 && VAR2 && VAR3
可以写为
ifneq ($(and $(VAR1),$(VAR2),$(VAR3)),)
在相关说明中，可能和函数需要版本3.81或更高版本.
如果某些已定义的变量可能是空字符串，如果我们准备以下功能:
ifndef_any_of = $(filter undefined,$(foreach v,$(1),$(origin $(v))))
ifdef_any_of = $(filter-out undefined,$(foreach v,$(1),$(origin $(v))))
然后满足以下条件:
ifdef VAR1 || VAR2
ifdef VAR1 && VAR2
可以分别使用调用
来编写a>函数:
ifneq ($(call ifdef_any_of,VAR1 VAR2),)
ifeq ($(call ifndef_any_of,VAR1 VAR2),)
In my Makefile I would like to check the following complex condition:
ifdef VAR1 || VAR2 || VAR3
action
endif
however the documentation says the syntax like that is not supported. So the only simple workaround that came to my mind is to use the concatenation:
ifneq ($(VAR1)$(VAR2)$(VAR3),)
action
endif
Are there any other more correct solutions?
For the following case:
ifdef VAR1 && VAR2 && VAR3
action
endif
one need to write
ifdef VAR1
ifdef VAR2
ifdef VAR3
action
endif
endif
endif
which is also ugly. Are there more elegant alternatives?
If your make is GNU-make and all the defined variables include a non-spacecharacter,
ifdef VAR1 && VAR2 && VAR3
can be written as
ifneq ($(and $(VAR1),$(VAR2),$(VAR3)),)
On a related note, probably and function requires version 3.81 or later.
In case some defined variables may be empty strings,if we prepare the following functions:
ifndef_any_of = $(filter undefined,$(foreach v,$(1),$(origin $(v))))
ifdef_any_of = $(filter-out undefined,$(foreach v,$(1),$(origin $(v))))
then the following conditions:
ifdef VAR1 || VAR2
ifdef VAR1 && VAR2
can be written respectively using call function:
ifneq ($(call ifdef_any_of,VAR1 VAR2),)
ifeq ($(call ifndef_any_of,VAR1 VAR2),)
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