在依赖包中使用的 CMake 宏

当一个包的配方想要通过宏提供 CMake 功能时，可以这样做。假设我们有一个名为 pkg 的配方，它将“导出”并“打包”一个名为 Macros.cmake 的文件，其中包含一个名为 pkg_macro() 的 CMake 宏。

pkg/conanfile.py

from conan import ConanFile
from conan.tools.files import copy

class Pkg(ConanFile):
    name = "pkg"
    version = "0.1"
    package_type = "static-library"
    # Exporting, as part of the sources
    exports_sources = "*.cmake"

    def package(self):
        # Make sure the Macros.cmake is packaged
        copy(self, "*.cmake", src=self.source_folder, dst=self.package_folder)

    def package_info(self):
        # We need to define that there are "build-directories", in this case
        # the current package root folder, containing build files and scripts
        self.cpp_info.builddirs = ["."]

pkg/Macros.cmake

function(pkg_macro)
    message(STATUS "PKG MACRO WORKING!!!")
endfunction()

当这个包被创建时（cd pkg && conan create .），它可以被其他包配方使用，例如这个应用程序：

app/conanfile.py

from conan import ConanFile
from conan.tools.cmake import CMake

class App(ConanFile):
    package_type = "application"
    generators = "CMakeToolchain", "CMakeDeps"
    settings = "os", "compiler", "arch", "build_type"
    requires = "pkg/0.1"

    def build(self):
        cmake = CMake(self)
        cmake.configure()
        cmake.build()

它有这个 CMakeLists.txt 文件：

app/CMakeLists.txt

cmake_minimum_required(VERSION 3.15)
project(App LANGUAGES NONE)

include(Macros)  # include the file with the macro (note no .cmake extension)
pkg_macro()  # call the macro

所以当我们进行本地构建时，我们会看到文件是如何被包含以及宏是如何被调用的。

$ cd app
$ conan build .
PKG MACRO WORKING!!!