小编asu*_*ang的帖子

我的CMakeLists.txt中有以下CMake代码段:

cmake_minimum_required(VERSION 2.8.8 FATAL_ERROR)

message(STATUS "Before setting - ${MY_VARIABLE}")

# first check
if(NOT DEFINED ${MY_VARIABLE})
  set(MY_VARIABLE true)
endif(NOT DEFINED ${MY_VARIABLE})

message(STATUS "After setting - ${MY_VARIABLE}")

# second check
if(NOT DEFINED ${MY_VARIABLE})
  message(STATUS "What - ${MY_VARIABLE}")
endif(NOT DEFINED ${MY_VARIABLE})

CMake配置的输出是:

-- The C compiler identification is GNU 4.8.4
-- The CXX compiler identification is GNU 4.8.4
-- Check for working C compiler: /usr/local/bin/cc
-- Check for working C compiler: /usr/local/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C …