package()¶

The package() method is in charge of copying files from the source_folder and the temporary build_folder to the package_folder, copying only those files and artifacts that will be part of the final package, like headers, compiler static and shared libraries, executables, license files, etc.

The package() method will be called once per different configuration that is creating a new package binary, which happens with conan install --build=pkg*, conan create and conan export-pkg commands.

There are 2 main ways the package() method can do such a copy. The first one is an explicit copy() from the origin source_folder and build_folder to the package folder:

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

class Pkg(ConanFile):

    def package(self):
        # copying headers from source_folder
        copy(self, "*.h", join(self.source_folder, "include"), join(self.package_folder, "include"))
        # copying compiled .lib from build folder
        copy(self, "*.lib", self.build_folder, join(self.package_folder, "lib"), keep_path=False)

The second way is to use the install functionality of some build systems, provided that the build scripts implement such functionality. For example if the CMakeLists.txt of a package implements the correct CMake INSTALL instructions, it is possible to do:

def package(self):
    cmake = CMake(self)
    cmake.install()

Also, it is possible to combine both approaches, doing cmake.install() and also adding some copy() calls, for example to make sure some “License.txt” file is packaged that was not taken into account by the CMakeLists.txt script.

It is also possible to use conditionals in the package() method, because different platforms might have different artifacts in different locations:

def package(self):
    if self.settings.os == "Windows":
        copy(self, "*.lib", src=os.path.join(self.build_folder, "libs"), ...)
        copy(self, "*.dll", ....)
    else:
        copy(self, "*.lib", src=os.path.join(self.build_folder, "build", "libs"), ...)

Though in most situations it might not be necessary, because pattern based copy will likely not find wrong artifacts like *.dll in a non-Windows build.

The package() method is also the one called when packaging precompiled binaries with conan export-pkg. In this case the self.source_folder and self.build_folder refer to user space folders, as defined by the layout() method and the only folder in the Conan cache will be self.package_folder.

Note

Best practices

The cmake.install() functionality should be called in the package() method, not in the build() method. It is not necessary to reuse the CMake(self) object, it shouldn’t be reused among methods. Creating a new instance in every method is the recommended approach.