Custom Conan generators

In the case that you need to use a build system or tool that is not supported by Conan off-the-shelf, you could create your own custom integrations using a custom generator. This can be done in three different ways.

Custom generators as python_requires

One way of having your own custom generators in Conan is by using them as python_requires. You could declare a MyGenerator class with all the logic to generate some files inside the mygenerator/1.0 python_requires package:

mygenerator/conanfile.py

from conan import ConanFile
from conan.tools.files import save


class MyGenerator:
    def __init__(self, conanfile):
        self._conanfile = conanfile

    def generate(self):
        deps_info = ""
        for dep, _ in self._conanfile.dependencies.items():
            deps_info += f"{dep.ref.name}, {dep.ref.version}\n"
        save(self._conanfile, "deps.txt", deps_info)


class PyReq(ConanFile):
    name = "mygenerator"
    version = "1.0"
    package_type = "python-require"

And then conan create mygenerator and use it in the generate method of your own packages like this:

pkg/conanfile.py

from conan import ConanFile


class MyPkg(ConanFile):
    name = "pkg"
    version = "1.0"

    python_requires = "mygenerator/1.0"
    requires = "zlib/1.3.1", "bzip2/1.0.8"

    def generate(self):
        mygenerator = self.python_requires["mygenerator"].module.MyGenerator(self)
        mygenerator.generate()

Then, doing a conan install pkg on this pkg recipe, will create a deps.txt text file containing:

zlib, 1.2.11
bzip2, 1.0.8

This has the advantage that you can version your own custom generators as packages and also that you can share those generators as Conan packages.

Using global custom generators

You can also use your custom generators globally if you store them in the [CONAN_HOME]/extensions/generators folder. You can place them directly in that folder or install with the conan config install command.

[CONAN_HOME]/extensions/generators/mygen.py

from conan.tools.files import save


class MyGenerator:
    def __init__(self, conanfile):
        self._conanfile = conanfile

    def generate(self):
        deps_info = ""
        for dep, _ in self._conanfile.dependencies.items():
            deps_info = f"{dep.ref.name}, {dep.ref.version}"
        save(self._conanfile, "deps.txt", deps_info)

Then you can use them by name in the recipes or in the command line using the -g argument:

conan install --requires=zlib/1.2.13 -g MyGenerator

Generators from tool_requires

Warning

This feature is experimental and subject to breaking changes. See the Conan stability section for more information.

A direct dependency tool requires can also be used to provide custom generators. The following example shows how to create a custom generator that generates a file with the dependencies of the package, just like the example above, but using a tool_require instead of a python_require to inject the generator into the recipe, by adding them to the self.generator_info attribute inside the package_info method. Note that this attribute is None by default, so you need to set it explicitly to a list of generators.

mygenerator/conanfile.py

from conan import ConanFile
from conan.tools.files import save

class MyGenerator:
    def __init__(self, conanfile):
        self._conanfile = conanfile

    def generate(self):
        deps_info = ""
        for dep, _ in self._conanfile.dependencies.items():
            deps_info = f"{dep.ref.name}, {dep.ref.version}"
        save(self._conanfile, "deps.txt", deps_info)

class MyToolReq(ConanFile):
    name = "mygenerator-tool"
    version = "1.0"

    def package_info(self):
        self.generator_info = [MyGenerator]

And then having a tool_requires in your recipe for the mygenerator-tool package will automatically inject the generator into the recipe.

Note

Note that built-in generators can also be injected using tool_requires, by adding them by name: self.generator_info = ["CMakeDeps"]. tool_require’ing this package will inject the CMakeDeps generator into the recipe just as if it was declared in its generators attribute.