A custom Conan generator which produces cmake paths based on environment variables

cmake_user_paths.py

# This is intended to demonstrate a proof-of-concept 
# for users/callers of Conan to easily override
# conan-generated paths for dependencies.
# The purpose was to show how users could manually
# implement "editable" packages.

# It works, however, sadly, not the way intended. 
# Environment variables from profiles are not
# made available in generators.  os.getenv() returns
# only environment variables set in the outer shell.
# so, to properly compose the editable packages 
# would need to be done entirely in the shell, which
# is unfortunate, because the "shell" is not x-platform.
# It could also be done via python wrappers as well.

import os
from conans.model import Generator


class cmake_paths_from_env(Generator):
    
    output = []

    @property
    def filename(self):
        return "conanbuildinfo.user.cmake"

    @property
    def content(self):
        self.iterate_deps()
        return "\n".join(self.output)
      
    def iterate_deps(self):
        for dep_name, _ in self.deps_build_info.dependencies:
            self.process_dep(dep_name)
            
    def process_dep(self, dep_name):
        dep_root = os.getenv("CONAN_{0}_ROOT".format(dep_name.upper()))
        if dep_root:
            self.append_var(dep_name, "ROOT")
            self.process_subdirs(dep_name, dep_root)            
            
    def process_subdirs(self, dep_name, dep_root):   
        for var in ["INCLUDE_DIRS", "LIB_DIRS", "BIN_DIRS"]:
            var_name_full = "{0}_{1}".format(dep_name, var_name)
            val = os.getenv(var_name_full)
            if val:
                self.append_var(dep_name, self.cmake_join(dep_root, var_name_full))
       
    def append_var(var, val):
        self.output.append("set({0} {1})".format(var, val))
            
    @staticmethod   
    def cmake_join(path1, path2):
        return "{0}/{1}".format(path1, path2).replace("//","/")