Conan

# 环境
ubuntu:bionic的docker image
```shell
docker run -it ubuntu:bionic
```
预装工具
```shell
apt-get install cmake
```
# 安装conan
```shell
# pip3 install conan
Collecting conan
# conan -v
Conan version 1.33.0
```
# 使用conan
>官方文档：https://docs.conan.io/en/latest/getting_started.html

## 搜索包
```shell
# conan search poco --remote=conan-center
WARN: Remotes registry file missing, creating default one in /root/.conan/remotes.json
Existing package recipes:
poco/1.8.1          <<< 已有的版本
poco/1.9.3
poco/1.9.4
poco/1.10.0
poco/1.10.1
```
## 导入包
```shell
# conan inspect poco/1.9.4
poco/1.9.4: Not found in local cache, looking in remotes...
poco/1.9.4: Trying with 'conan-center'...
Downloading conanmanifest.txt completed [0.59k]                         
Downloading conanfile.py completed [12.59k]                            
Downloading conan_export.tgz completed [0.30k]              
Decompressing conan_export.tgz completed [0.00k]       
poco/1.9.4: Downloaded recipe revision 0
name: poco
version: 1.9.4
url: https://github.com/conan-io/conan-center-index
homepage: https://pocoproject.org
license: BSL-1.0
```

## 编译
```shell
# conan profile new default --detect
Found gcc 7
Found clang 6.0
gcc>=5, using the major as version

************************* WARNING: GCC OLD ABI COMPATIBILITY ***********************
 
Conan detected a GCC version > 5 but has adjusted the 'compiler.libcxx' setting to
'libstdc++' for backwards compatibility.
Your compiler is likely using the new CXX11 ABI by default (libstdc++11).

If you want Conan to use the new ABI for the default profile, run:

    $ conan profile update settings.compiler.libcxx=libstdc++11 default

Or edit '/root/.conan/profiles/default' and set compiler.libcxx=libstdc++11

************************************************************************************

# conan profile update settings.compiler.libcxx=libstdc++11 default
```
准备三个文件放在同一个目录如：`conan`中
```
conan$ ls
CMakeLists.txt  conanfile.txt md5.cpp

文件内容：

conan$ cat conanfile.txt 
[requires]
 poco/1.9.4

 [generators]
 cmake
 
conan$ cat md5.cpp 
#include "Poco/MD5Engine.h"
#include "Poco/DigestStream.h"

#include <iostream>

int main(int argc, char** argv){
    Poco::MD5Engine md5;
    Poco::DigestOutputStream ds(md5);
    ds << "abcdefghijklmnopqrstuvwxyz";
    ds.close();
    std::cout << Poco::DigestEngine::digestToHex(md5.digest()) << std::endl;
    return 0;
}

conan$ cat CMakeLists.txt 
cmake_minimum_required(VERSION 2.8.12)
 project(MD5Encrypter)

 add_definitions("-std=c++11")

 include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
 conan_basic_setup()

 add_executable(md5 md5.cpp)
 target_link_libraries(md5 ${CONAN_LIBS})
 ```
 ## conan编译
```shell
conan# mkdir build && cd build
build# conan install ..
Configuration:
[settings]
arch=x86_64
arch_build=x86_64
build_type=Release
compiler=gcc
compiler.libcxx=libstdc++11
compiler.version=7
os=Linux
os_build=Linux
conanfile.txt: Generated conaninfo.txt
conanfile.txt: Generated graphinfo

build# cmake .. -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Release
-- The C compiler identification is GNU 7.5.0
-- The CXX compiler identification is GNU 7.5.0
-- Configuring done
-- Generating done
-- Build files have been written to: /root/build

build# cmake --build .
Scanning dependencies of target md5
[ 50%] Building CXX object CMakeFiles/md5.dir/md5.cpp.o
[100%] Linking CXX executable bin/md5
[100%] Built target md5

build# ls
CMakeCache.txt  Makefile  cmake_install.cmake  conanbuildinfo.cmake  conaninfo.txt
CMakeFiles      bin       conan.lock           conanbuildinfo.txt    graph_info.json

build# ./bin/md5
c3fcd3d76192e4007dfb496cca67e13b
```
环境完成！

## 打包项目
>官网打包教程：https://docs.conan.io/en/latest/creating_packages/getting_started.html

下面要解决的问题是conanfile.txt中的conan包是怎么生成的。按照官网的打包步骤走了一遍，把源码打包成一个conan包。假设我们要将一个hello的源码打包成一个conan包

### 准备源码
```shell
# mkdir mypkg && cd mypkg
//这里会从github上下载hello的程序
/mypkg# conan new hello/0.1 -t  
```
### 编译成conan包
+ 方法1：
```shell
/mypkg# conan create . demo/testing
[100%] Built target example
hello/0.1@demo/testing (test package): Running test()
Hello World Release!         <<< 执行hello程序
```
+ 方法2：

上面的编译步骤等价于
```shell
/mypkg# conan export . demo/testing
/mypkg# conan install hello/0.1@demo/testing --build=hello
# package is created now, use test to test it
/mypkg# conan test test_package hello/0.1@demo/testing
hello/0.1@demo/testing (test package): Running test()
Hello World Release!         <<< 执行hello程序
```
### 查看生成的包
```shell
# conan search hello 
Existing package recipes:

hello/0.1@demo/testing
```
说明已经将hello的程序源码打包成了conan包。