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继续翻译 When you add to a variable's value with `+=', `make' actsessentially as if you had included the extra text in the initialdefinition of the variable. If you defined it first with `:=', makingit a simply-expanded variable, `+=' adds to that simply-expandeddefinition, and expan 阅读全文
posted @ 2012-10-04 10:55
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继续翻译6.6 Appending More Text to Variables====================================Often it is useful to add more text to the value of a variable alreadydefined. You do this with a line containing `+=', like this: objects += another.oThis takes the value of the variable `objects', and adds the text 阅读全文
posted @ 2012-10-04 10:28
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继续翻译6.5 Setting Variables=====================To set a variable from the makefile, write a line starting with thevariable name followed by `=' or `:='. Whatever follows the `=' or`:=' on the line becomes the value. For example, objects = main.o foo.o bar.o utils.odefines a variable n 阅读全文
posted @ 2012-10-04 10:05
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继续翻译6.4 How Variables Get Their Values==================================Variables can get values in several different ways: * You can specify an overriding value when you run `make'. *Note Overriding Variables: Overriding. * You can specify a value in the makefile, either with an assignment... 阅读全文
posted @ 2012-10-04 09:32
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上例子首先，在linux 环境中，如此设置:#test=1234567#export test#echo $test1234567#然后编辑 Makefileall: @echo $(test)运行结果:#make 1234567#结束 阅读全文
posted @ 2012-10-04 09:29
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上例子gao:=123all: @echo $(gao)如果运行 make ,结果是 123如果运行 make gao=456, 结果是456那么如果改变一下呢。比如我们想要：即便你在命令行给出了变量的值，我也不想放弃呢？修改例子：override gao:=123all: @echo $(gao)如果运行 make ,结果是 123因为有 override 的存在，make gao=456 的结果仍然是 123结束 阅读全文
posted @ 2012-10-04 09:02
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继续翻译 The only restriction on this sort of use of nested variablereferences is that they cannot specify part of the name of a functionto be called. This is because the test for a recognized function nameis done before the expansion of nested references. For example, ifdef do_sort func := sort ... 阅读全文
posted @ 2012-10-04 08:51
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继续翻译 A computed variable name need not consist entirely of a singlevariable reference. It can contain several variable references, aswell as some invariant text. For example, a_dirs := dira dirb 1_dirs := dir1 dir2 a_files := filea fileb 1_files := file1 file2 ifeq "$(use_a)"... 阅读全文
posted @ 2012-10-04 08:10
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继续翻译 The previous example shows two levels of nesting, but any number oflevels is possible. For example, here are three levels: x = y y = z z = u a := $($($(x)))Here the innermost `$(x)' expands to `y', so `$($(x))' expands to`$(y)' which in turn expands to `z'; now we have `$(z) 阅读全文
posted @ 2012-10-04 08:04
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