Use conanfile.py for consumers¶
You can use a
conanfile.py for installing/consuming packages, even if you are not creating a package with it. You can also use the existing
conanfile.py in a given package while developing it to install dependencies, no need to have a separate
Let’s take a look at the complete
conanfile.txt from the previous timer example with POCO library, in which we have added a couple of extra generators
[requires] Poco/1.7.8p3@pocoproject/stable [generators] gcc cmake txt [options] Poco:shared=True OpenSSL:shared=True [imports] bin, *.dll -> ./bin # Copies all dll files from the package "bin" folder to my project "bin" folder lib, *.dylib* -> ./bin # Copies all dylib files from the package "lib" folder to my project "bin" folder
conanfile.py file is:
from conans import ConanFile, CMake class PocoTimerConan(ConanFile): settings = "os", "compiler", "build_type", "arch" requires = "Poco/1.7.8p3@pocoproject/stable" # comma-separated list of requirements generators = "cmake", "gcc", "txt" default_options = "Poco:shared=True", "OpenSSL:shared=True" def imports(self): self.copy("*.dll", dst="bin", src="bin") # From bin to bin self.copy("*.dylib*", dst="bin", src="lib") # From lib to bin
Note that this
conanfile.py doesn’t have a name, version, or
package() method, as it is not creating a package, they are not required.
conanfile.py you can just work as usual, nothing changes from the user’s perspective.
You can install the requirements with (from mytimer/build folder):
$ conan install ..
One advantage of using
conanfile.py is that the project build can be further simplified,
using the conanfile.py
If you are building your project with CMake, edit your
conanfile.py and add the following
from conans import ConanFile, CMake class PocoTimerConan(ConanFile): settings = "os", "compiler", "build_type", "arch" requires = "Poco/1.7.8p3@pocoproject/stable" generators = "cmake", "gcc", "txt" default_options = "Poco:shared=True", "OpenSSL:shared=True" def imports(self): self.copy("*.dll", dst="bin", src="bin") # From bin to bin self.copy("*.dylib*", dst="bin", src="lib") # From lib to bin def build(self): cmake = CMake(self) cmake.configure() cmake.build()
Then execute, from your project root:
$ conan install . --install-folder build $ conan build . --build-folder build
The conan install command downloads and prepares the requirements of your project
(for the specified settings) and the conan build command uses all that information
to invoke your
build() method to build your project, which in turn calls
This conan build will use the settings used in the conan install which have been cached in the local conaninfo.txt and file
in your build folder, which simplifies the process and reduces the errors of mismatches between the installed packages and the current
project configuration. Also, the conanbuildinfo.txt file contains all the needed information obtained from the requirements:
If you want to build your project for x86 or another setting just change the parameters passed to conan install:
$ conan install . --install-folder build_x86 -s arch=x86 $ conan build . --build-folder build_x86
Implementing and using the conanfile.py
build() method ensures that we always use the same
settings both in the installation of requirements and the build of the project, and simplifies
calling the build system.
Other local commands¶
Conan implements other commands that can be executed locally over a consumer
conanfile.py which is in user space, not in the local cache:
- conan source <path>: Execute locally the conanfile.py
- conan package <path>: Execute locally the conanfile.py
These commands are mostly used for testing and debugging while developing a new package, before exporting such package recipe into the local cache.
Check the section Reference/Commands to find out more.