这是什么样的Makefile变量分配? [英] What kind of Makefile variable assignment is this?

问题描述

我使用简单的makefile已有多年了，但是直到最近才被分配来学习大量复杂的由Autotools生成的makefile来来往往的任务，这些文件用于我的雇主购买的代码库.在这些代码中，我遇到了如下的变量声明:

I've used simple makefiles for years, but only recently been assigned the task of learning the ins and outs of a large, complicated set of Autotools-generated makefiles which is used for a code base my employer has bought. In these, I'm running into variable declarations like the following:

QOBJECT_MOCSRCS = $(QOBJECT_HEADER:%.h=.gen/moc_%.cpp) \
                  $(QOBJECT_SRCS:%.cpp=.gen/moc_%.cpp)

QOBJECT_DEPS = $(QOBJECT_MOCSRCS:%.cpp=.deps/%.Po)

我从上下文中得出的最佳猜测是，这些建立的文件名列表由构建过程提供，例如QOBJECT_MOCSRCS应该以(a).h文件，(b).cpp文件的列表结尾，基于在构建过程中将在临时目录./gen中生成的一组中间.cpp文件的词干名称的％.这用于存储moc _％.cpp文件，这些文件是通过使用Qt的moc工具构建Qt文件而输出的...令我发疯的是，我无法在任何中找到任何内容make 文档(主要是GNU make手册)，该文档告诉我这种声明样式的含义，因此我可以对其进行跟踪并掌握语法. $()的内容看起来有点像规则，GNU中最接近的等效内容使手册似乎是指定特定于目标的变量值的规则，但是我不知道这是否接近正确的读数.谁能给我指出一个合适的学习参考书?

My best guess from context is that these set up lists of names of files to be provided by the build process, eg., QOBJECT_MOCSRCS should end up as a list of (a) .h files, (b) .cpp files, based on the % stem names of a set of intermediate .cpp files which will be generated during the build, in a temporary directory ./gen. This is used to store the moc_%.cpp files which are output as a result of a build of Qt files with Qt's moc tool...what is driving me crazy, is that I have been unable to find anything in any make documentation I've got (mostly the GNU make manual) that tells me what this style of declaration is called, so I can track it down and get a grip on the syntax. The contents of the $() look sort of like rules, and the nearest equivalents in the GNU make manual seem to be rules specifying target-specific variable values, but I have no idea whether this is anywhere near a correct reading. Can anyone point me to an appropriate reference for study?

推荐答案

此功能称为替换引用，

This feature is called substitution references, http://www.gnu.org/software/make/manual/html_node/Substitution-Refs.html#Substitution-Refs

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