为什么 Makefile 中 */%/x 不匹配 a/b/x？

发布于 2024-10-07 20:52:12 字数 270 浏览 0 评论 0原文

在 Makefile 代码中解释...

PATH = a/b/x
$(patsubst a/%/x,%,$(PATH))    # => b
$(patsubst */%/x,%,$(PATH))    # => a/b/x

似乎这两个都应该产生相同的结果，b，因为 * 应该匹配任何内容。为什么情况并非如此？如何编写一个表达式来捕获带有任何前缀的中心术语，而不仅仅是“a”？

原文

Explained in Makefile code…

PATH = a/b/x
$(patsubst a/%/x,%,$(PATH))    # => b
$(patsubst */%/x,%,$(PATH))    # => a/b/x

It seems like both of these should produce the same result, b, as the * should match anything. Why is this not the case? How do I write one expression to capture the center term with any prefix, not just 'a'?

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若能看破又如何 2024-10-14 20:52:12

Make 根本没有很好的处理通配符的能力。您的 $(patsubst */%/x,%,$(PATH)) 不起作用，因为您的 $(PATH)< 中没有 * /代码>。但你可以通过这个组合获得你想要的效果：

$(word 2, $(subst /, ,$(PATH)))

Make simply doesn't have very good ability to handle wildcards. Your $(patsubst */%/x,%,$(PATH)) doesn't work because there is no * in your $(PATH). But you can get the effect you want with this kludge: