在ExternalProject_Add命令中INSTALL_DIR有什么用? [英] What is INSTALL_DIR useful for in ExternalProject_Add command?

问题描述

我不了解ExternalProject_Add命令中INSTALL_DIR的用法.我尝试使用它，但是它似乎不起作用.这是使用快速编译的Eigen库的CMakeLists.txt的示例:

I don't understand the usage of INSTALL_DIR in ExternalProject_Add command. I try to use it but it does not seem to work. Here is an example of a CMakeLists.txt, using Eigen library which compiles quickly:

cmake_minimum_required (VERSION 2.6)
project (example CXX)
include(ExternalProject)
include(ProcessorCount)
set(CMAKE_VERBOSE_MAKEFILE ON)
ProcessorCount(N)
if(NOT N EQUAL 0)
   set(CMAKE_BUILD_FLAGS -j${N})
endif()
ExternalProject_Add
(
    mylib
    PREFIX myprefix
    DOWNLOAD_COMMAND wget http://bitbucket.org/eigen/eigen/get/3.2.4.tar.gz && tar xvzf 3.2.4.tar.gz -C mylib --strip-components=1
)

我选择了以下项目层次结构:

I chose the following project hierarchy:

project
    CMakeLists.txt
    build/

在构建存储库中，输入:

From build repository, I type:

cmake ..
make

安装过程失败，并显示以下消息:

The installation process fails with the following message:

文件无法创建目录:/usr/local/include/eigen3.
可能需要管理权限.

file cannot create directory: /usr/local/include/eigen3.
Maybe need administrative privileges.

据我了解，这意味着我需要在配置步骤中定义一个前缀":

As far as I understand, it means that I need to define a "prefix" during the configuration step:

cmake -D CMAKE_INSTALL_PREFIX=$INSTALL_DIR ..

但是，已经在ExternalProject_Add命令中定义了INSTALL_DIR变量.但是，通过添加

But, the INSTALL_DIR variable is already defined in the ExternalProject_Add command. However, I get the same error when I modify the value of INSTALL_DIR by adding

INSTALL_DIR myprefix/src/install

在ExternalProject_Add命令中.

in the ExternalProject_Add command.

那么，INSTALL_DIR有什么用? 我在做什么错了?

So, what is INSTALL_DIR useful for? What am I doing wrong?

当然，我知道如何提供自己的配置命令来添加前缀并解决问题.但这不是我的问题.我的问题是:如果必须这样做，INSTALL_DIR的目的是什么?

Of course, I know how to provide my own configuration command to add a prefix and solve the problem. But it is not my question. My question is: if I have to do that, what is the purpose of INSTALL_DIR?

推荐答案

从我在这次讨论中发现的内容

From what I found in this discussion https://www.mail-archive.com/[e-mail]/msg51663.html (scroll to the end of the page to navigate through the thread messages) it is indeed pretty common thing to use CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${CMAKE_BINARY_DIR}/contrib

此外，通过潜入ExternalProject.cmake模块，我发现设置该目录的唯一作用是CMake将在执行其他操作之前创建在INSTALL_DIR中指定的目录.

Furthermore, lurking through the ExternalProject.cmake module I found out that the only effect setting this directory has is that CMake will create directory specified in INSTALL_DIR before doing anything else.

此外，它将设置您可以通过ExternalProject_Get_Property(${project_name} install_dir)命令收集的属性.

Also, it will set the property that you can gather through ExternalProject_Get_Property(${project_name} install_dir) command.

差不多了.

//自CMake 3.2.2版起

// As of CMake version 3.2.2

这篇关于在ExternalProject_Add命令中INSTALL_DIR有什么用?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IT屋！