Conan: How to get the source folder of a dependency from within `conanfile.py`?

The easiest way to get dependency path is:

from conans import ConanFile # for type hinting

# conan create
boost: ConanFile = self.dependencies.build["boost"]
boost.package_folder

but it will not work always:

• self.dependencies is none when dependency tree is not evaluated, for example during conan build https://github.com/conan-io/conan/issues/10535 you can use this hacky workaround:

# conan build (hacky)
self.deps_cpp_info["boost"].build_paths[0]

• it might not be available in all steps (I did not check in detail)

The most reliable way to get this information is actually to read if from conanbuildinfo.txt - this file is created during install step, you can use different generators, like -g json to use it in different formats. You can read this file using conan api:

from conans.client.generators import TXTGenerator
with open("conanbuildinfo.txt", "r") as handle:
    contents = handle.read()
deps_cpp_info, deps_user_info, deps_env_info, user_info_build = TXTGenerator.loads(contents)

And the last way that I found in my code (this can be simplified, but that is what I can provide for now):

import sys

import conans.errorsc
import conans.cli.exit_codes
from conans import ConanFile

from conans.client.cache.cache import ClientCache
from conans.client.conan_api import Conan
from conans.model.ref import PackageReference
from conans.paths.package_layouts.package_editable_layout import PackageEditableLayout

try:
    conan_api, _, _ = Conan.factory()
except conans.errors.ConanMigrationError:
    sys.exit(conans.cli.exit_codes.ERROR_MIGRATION)
except conans.errors.ConanException as error:
    sys.exit(conans.cli.exit_codes.ERROR_GENERAL)


def _discover_package_path(dependency_name: str) -> str:
    """Returns a package folder in local conan cache for specified dependency.
    Function is similar to:
    > conan info conanfile.py --paths --only package_folder
    This implementation is based on _grab_info_data (Conan version 1.55.0-dev):
    >>> from conans.client.conan_command_output import CommandOutputer
    >>> CommandOutputer._grab_info_data
    """
    data, _ = conan_api.info(reference_or_path="conanfile.py")
    node = next(node for node in data.nodes if node.name == dependency_name)
    cache = ClientCache(conan_api.cache_folder, conan_api.out)
    layout = cache.package_layout(node.ref, node.conanfile.short_paths)
    if isinstance(layout, PackageEditableLayout):
        return node.conanfile.package_folder
    else:
        return layout.package(PackageReference(node.ref, node.package_id))


# _discover_package_path("cmake")

class MyDummy(ConanFile):
    name = "MyDummy"
    version = "0.0.1"
    requires = "boost/1.71.0"

    def build(self):
        print(80 * "#")
        print(_discover_package_path("boost"))
        print(80 * "#")