CppInfo class represents the basic C++ usage information of a given package, like the
libdirs, library names, etc. It is the information that the consumers of the package need in order to be able to find the headers and link correctly with the libraries.
self.cpp_info object in the
package_info() is a
CppInfo object, so in most cases it will not be necessary to explicitly instantiate it, and using it as explained in the package_info() section would be enough.
This section describes the other, advanced uses cases of the
Aggregating information in custom generators¶
This feature is experimental and subject to breaking changes. See the Conan stability section for more information.
Some generators, like the built-in
NMakeDeps, contains the equivalent to this code, that collapses all information from all dependencies into one single
CppInfo object that aggregates all the information
from conan.tools import CppInfo ... def generate(self): aggregated_cpp_info = CppInfo(self) deps = self.dependencies.host.topological_sort deps = [dep for dep in reversed(deps.values())] for dep in deps: # We don't want independent components management, so we collapse # the "dep" components into one CppInfo called "dep_cppinfo" dep_cppinfo = dep.cpp_info.aggregated_components() # Then we merge and aggregate this dependency "dep" into the final result aggregated_cpp_info.merge(dep_cppinfo) aggregated_cpp_info.includedirs # All include dirs from all deps, all components aggregated_cpp_info.libs # All library names from all deps, all components aggregated_cpp_info.system_libs # All system-libs from all deps .... # Creates a file with this information that the build system will use
This aggregation could be useful in cases where the build system cannot easily use independent dependencies or components. For example
Autotools mechanism to provide dependencies information would be via
CXXFLAGS and similar variables. These variables are global, so passing all the information from all dependencies is the only possibility.
The public documented interface (besides the defined one in the package_info()) is:
CppInfo(conanfile): Constructor. Receives a
conanfileas argument, typically
aggregated_components(): return a new
CppInfoobject resulting from the aggregation of all the components
get_sorted_components(): Get the ordered components of a package, prioritizing those with fewer dependencies within the same package. Returns an
OrderedDictof sorted components in the format
merge(other_cppinfo: CppInfo): modifies the current
CppInfoobject, updating it with the information of the parameter
other_cppinfo, allowing to aggregate information from multiple dependencies.