.. _understand_packaging: Understanding packaging ======================== Manual package creation and testing ----------------------------------- The previous **create** approach using *test_package* subfolder, is not strictly necessary, though **very strongly recommended**. If we didn't want to use the *test_package* functionality, we could just write our recipe ourselves or use the :command:`conan new` command without the :command:`-t`. command line argument. .. code-block:: bash $ mkdir mypkg && cd mypkg $ conan new Hello/0.1 This will create just the *conanfile.py* recipe file. Now we could create our package: .. code-block:: bash $ conan create demo/testing This would be equivalent to: .. code-block:: bash $ conan export . demo/testing $ conan install Hello/0.1@demo/testing --build=Hello Once the package is there, it can be consumed like any other package, just add ``Hello/0.1@demo/testing`` to some project *conanfile.txt* or *conanfile.py* requirements and run: .. code-block:: bash $ conan install . # build and run your project to ensure the package works The package creation process ---------------------------- It is very useful for package creators and conan users in general to understand the flow of package creation inside the conan local cache, and its layout. For every package recipe, there are 5 important folders in the **local cache**: - **export**: The folder where the package recipe is stored. - **export_source**: The folder where code copied with the recipe ``exports_sources`` attribute is stored. - **source**: Where the source code for building from sources is stored. - **build**: Where the actual compilation of sources is done. There will typically be one subfolder for each different binary configuration - **package**: Where the final package artifacts are stored. There will be one subfolder for each different binary configuration The *source* and *build* folders only exist when the packages have been built from sources. .. image:: /images/package_create_flow.png :height: 500 px :width: 600 px :align: center The process starts when a package is "exported", via the :command:`conan export` command or more typically, with the :command:`conan create` command. The *conanfile.py* and files specified by the ``exports_sources`` field are copied from the user space into the **local cache**. The *export* and *export_source* files are copied to the *source* folder, and then the ``source()`` method is executed (if existing). Note that there is only one source folder for all the binary packages. If some source code is to be generated that will be different for different configurations, it cannot be generated in the ``source()`` method, it has to be done in the ``build()`` method. Then, for each different configuration of settings and options, a package ID will be computed in the form of a SHA-1 hash of such configuration. Sources will be copied to the *build/hashXXX* folder, and the ``build()`` method will be triggered. After that, the ``package()`` method will be called to copy artifacts from the *build/hashXXX* folder to the *package/hashXXX* folder. Finally, the ``package_info()`` methods of all dependencies will be called and gathered to be able to generate files for the consumer build system, as the *conanbuildinfo.cmake* for the ``cmake`` generator. Also the ``imports`` feature will copy artifacts from the local cache into user space if specified. Any doubts? Please check out our :ref:`FAQ section ` or |write_us|. .. |write_us| raw:: html write us