Migrating legacy cpp_info attributes to set_property()

Migrating from .names, .filenams and .build_modules to set_property() is easy, but there are some details to take into account for properties like cmake_target_name and cmake_file_name. Let’s see some examples.

Important

The 2 mechanisms are completely independent:

Old way using .names, .filenames will work exclusively for legacy generators like cmake_find_package
New properties, like set_property("cmake_target_name") will work exclusively for new generators like CMakeDeps. They have changed to be absolute, and that would break legacy generators.
Recipes that want to provide support for both generators need to provide the 2 definitions in their package_info()

Migrating from .names to cmake_target_name

It is important to note that cmake_target_name is not going to take the same value as the .names attribute did. With the .names attribute, if you set a name for the target in CMake, Conan would automatically create a “namespaced” target name with that name. This code, for example:

def package_info(self):
    ...
    self.cpp_info.filenames["cmake_find_package"] = "myname"
    ...

Will create a CMake target named myname::myname.

The property cmake_target_name accepts complete target names. That means that the name you set with this property will be the one added to the CMake generated files without appending any more information to it. To translate the last example to the set_property model you should add the following declaration:

def package_info(self):
    ...
    self.cpp_info.set_property("cmake_target_name", "myname::myname")
    ...

Note that you can use whatever name you want, it can have a different namespace, like mynamespace::myname or use a name with no namespace at all.

Also, please note that you may want to have different target names for both config and module CMake generated files. For example, you have a package named myssl and you want to generate a Findmyssl.cmake module that declares the target MySSL::SSL, but for config mode you want to declare the target MySSL without namespaces. You can do that using the cmake_module_target_name property. Also, when setting this property, remember to set cmake_find_mode so that CMakeDeps generates those module files. Let’s see an example:

class MySSL(ConanFile):
    name = "myssl"
    version = "1.0"
    ...
    def package_info(self):
        self.cpp_info.set_property("cmake_target_name", "MySSL")
        self.cpp_info.set_property("cmake_module_target_name", "MySSL::SSL")
        self.cpp_info.set_property("cmake_find_mode", "both")
    ...

Migrating from .filenames to cmake_file_name

To migrate from .filenames to names just use the same .filenames value for the property cmake_file_name. For example:

def package_info(self):
    ...
    self.cpp_info.filenames["cmake_find_package"] = "MyFileName"
    self.cpp_info.filenames["cmake_find_package_multi"] = "MyFileName"
    ...

Could be declared like this with set_property():

def package_info(self):
    ...
    self.cpp_info.set_property("cmake_file_name", "MyFileName")
    ...

Please note that for the legacy .names and .filenames model, if .filenames is not declared but .names is, then Conan will automatically set the value of .filenames to the value of .names. So for example:

def package_info(self):
    ...
    self.cpp_info.names["cmake_find_package"] = "SomeName"
    self.cpp_info.names["cmake_find_package_multi"] = "SomeName"
    ...

This will use “SomeName” to compose the generated filenames. In this case you should set cmake_file_name to “SomeName”:

def package_info(self):
    ...
    self.cpp_info.set_property("cmake_file_name", "SomeName")
    ...

Also, please note that you may want to use different file names for both config and module CMake generated files. If we take the previous example of the myssl and you want to generate a FindMySSL.cmake for module mode and myssl-config.cmake for config mode, you can set the cmake_module_file_name to set the value for the module file:

class MySSL(ConanFile):
    name = "myssl"
    version = "1.0"
    ...
    def package_info(self):
        self.cpp_info.set_property("cmake_file_name", "myssl")
        self.cpp_info.set_property("cmake_module_file_name", "MySSL")
        self.cpp_info.set_property("cmake_find_mode", "both")
    ...

You can read more about this properties in the CMakeDeps properties reference.

Migrating components information

As we said, all these properties but cmake_file_name and cmake_module_file_name have components support, so for example:

def package_info(self):
    ...
    self.cpp_info.components["mycomponent"].names["cmake_find_package"] = "mycomponent-name"
    self.cpp_info.components["mycomponent"].names["cmake_find_package_multi"] = "mycomponent-name"
    self.cpp_info.components["mycomponent"].names["pkg_config"] = "mypkg-config-name"
    self.cpp_info.components["mycomponent"].build_modules.append(os.path.join("lib", "mypkg_bm.cmake"))
    ...

Could be declared like this with the properties model:

def package_info(self):
    ...
    self.cpp_info.components["mycomponent"].set_property("cmake_target_name", "component_namespace::mycomponent-name")
    # The property "cmake_build_modules" can't be declared in a component, do it in self.cpp_info
    self.cpp_info.set_property("cmake_build_modules", [os.path.join("lib", "mypkg_bm.cmake")])
    self.cpp_info.components["mycomponent"].set_property("pkg_config_name", "mypkg-config-name")
    self.cpp_info.components["mycomponent"].set_property("custom_name", "mycomponent-name", "custom_generator")
    ...

Please note that most of the legacy generators like cmake, cmake_multi, cmake_find_package, cmake_find_package_multi and cmake_paths do not listen to these properties at all, so if you want to maintain compatibility with consumers that use those generators and also that information for new generators like CMakeDeps you need both models living together in the same recipe.