Declaring the layout when creating packages for third-party libraries¶
Please, first clone the sources to recreate this project. You can find them in the examples2 repository in GitHub:
$ git clone https://github.com/conan-io/examples2.git
$ cd examples2/examples/conanfile/layout/third_party_libraries
If we have this project, intended to create a package for a third-party library whose code is located externally:
.
├── conanfile.py
└── patches
└── mypatch
The conanfile.py
would look like this:
...
class Pkg(ConanFile):
name = "hello"
version = "1.0"
exports_sources = "patches*"
...
def layout(self):
cmake_layout(self, src_folder="src")
# if you are declaring your own layout, just declare:
# self.folders.source = "src"
def source(self):
# we are inside a "src" subfolder, as defined by layout
# the downloaded soures will be inside the "src" subfolder
get(self, "https://github.com/conan-io/libhello/archive/refs/heads/main.zip",
strip_root=True)
# Please, be aware that using the head of the branch instead of an immutable tag
# or commit is not a good practice in general as the branch may change the contents
# patching, replacing, happens here
patch(self, patch_file=os.path.join(self.export_sources_folder, "patches/mypatch"))
def build(self):
# If necessary, the build() method also has access to the export_sources_folder
# for example if patching happens in build() instead of source()
#patch(self, patch_file=os.path.join(self.export_sources_folder, "patches/mypatch"))
cmake = CMake(self)
cmake.configure()
cmake.build()
...
We can see that the ConanFile.export_sources_folder
attribute can provide access to the root
folder of the sources:
Locally it will be the folder where the
conanfile.py
livesIn the cache it will be the “source” folder, that will contain a copy of
CMakeLists.txt
andpatches
, while the “source/src” folder will contain the actual downloaded sources.
We can check that everything runs fine now:
$ conan create .
...
Downloading main.zip
hello/1.0: Unzipping 3.7KB
Unzipping 100 %
...
[ 50%] Building CXX object CMakeFiles/hello.dir/src/hello.cpp.o
[100%] Linking CXX static library libhello.a
[100%] Built target hello
...
$ conan list hello/1.0
Local Cache
hello
hello/1.0
See also
Read more about the layout method and how the package layout works.