将Python嵌入Makefile中以设置make变量

问题描述

我有一个复杂的逻辑来检测Makefile变量的路径.我放弃了用make语言进行此操作，因此我用Python对其进行了编码，并希望将代码嵌入M​​akefile中以设置变量.但是，这不起作用:

I have a complex logic for detecting path for Makefile variable. I gave up on doing this in make language, so I coded it in Python, and want to embed the code into Makefile to set variable. However, this doesn't work:

define DETECT_SDK
import os
locations = [
  "../google_appengine",
  "/usr/local/google_appengine",
  "../.locally/google_appengine",
]
for path in locations:
  if os.path.exists(path):
    print(path)
    break
else:
  print(".")
endef

SDK_PATH ?= $(shell python -c $(DETECT_SDK))

default:
        python -c 'import sys; print(sys.argv)' $(SDK_PATH)

更新:更新了以前，它因Makefile:2: *** missing separator. Stop.失败.现在它失败并出现另一个错误:

UPDATE: Updated multiline definition from Is it possible to create a multi-line string variable in a MakefilePreviously it was failing with Makefile:2: *** missing separator. Stop.. Now it fails with another error:

/bin/sh: 1: Syntax error: "(" unexpected
python -c 'import sys; print(sys.argv)'
['-c']

推荐答案

您必须引用传递给Python的字符串:

You have to quote the string you pass to Python:

SDK_PATH ?= $(shell python -c '$(DETECT_SDK)')

否则，shell将在尝试解析Python脚本时会感到困惑.

Otherwise the shell will be confused trying to parse the Python script.

我不明白您的Python脚本.您的缩进是错误的，因此应该将else附加到if(grrr ...)上，否则您将丢失break语句...或者else可能是无用的.在撰写本文时，它将生成一个以换行符分隔的现有路径列表以及.".如果您描述的是您真正想做的事情，而不仅仅是说您放弃了，我们可以为您提供帮助.

I don't understand your Python script though. Either your indentation is wrong, so the else is supposed to be attached to the if (grrr...) or else you're missing a break statement... or possibly the else is just useless. As it's written, it will generate a newline-separated list of paths that exist, plus ".". If you describe what you're really trying to do, rather than just say you gave up, we can help.

例如，如果您要打印的是该列表或."中的第一个现有路径.如果不存在(即您的Python循环在print之后缺少break)，那么您可以在GNU make中轻松地做到这一点:

For example, if what you want to do is print the first existing path in that list or "." if none exist (that is, your Python loop is missing a break after the print), then you can easily do this in GNU make:

SDK_PATH_LIST = ../google/appengine /usr/local/google_appengine ../.locally/google_appengine
SDK_PATH ?= $(firstword $(wildcard $(SDK_PATH_LIST:%=%/.)) .)

这篇关于将Python嵌入Makefile中以设置make变量的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！