[question] Conan 2.0 Custom Generators

I have a few custom generators that help support pre-conan setups, defining extra environment variables and such. I am attempting to upgrade these to conan 2.0, but it appears that custom generators are not supported in conan 2.0. Looking at conans/client/loader.py, it requires all custom generators to be a subclass of conans.model.conan_file.Generator but the 2.0 generators (like VirtualRunEnv) don’t use that base class.

Presently, if a user wants to use this custom generator, then they run a command such as

conan install package/version@ -g my_generator

I asked on the slack page and was told that custom generators are planned to go away in conan 2.0. Is there a way to produce the above behavior in conan 2.0. I know that I could include a generator in the conanfile, but it is only needed in certain circumstances and its use is orthogonal to the recipe.

• I’ve read the CONTRIBUTING guide.

[memsharded]

I have added a test in https://github.com/conan-io/conan/pull/11605 to illustrate how this can be done. Basically, use Python flexibility:

from conan import ConanFile

        class MyGenerator:
            common = None
            def __init__(self, conanfile):
                self.conanfile = conanfile
            def generate(self):
                self.conanfile.output.info("VALUE TOOL: {}!!!".format(MyGenerator.common.mycommon()))

        class Tool(ConanFile):
            name = "tool"
            version = "0.1"
            python_requires = "common/0.1"
            def init(self):
                MyGenerator.common = self.python_requires["common"].module

We can put the python_require in the way it belongs, in the Tool(ConanFile), but make it available to different parts of the classes and functions to be reused.

[memsharded]

There is no explicit examples, but there exist docs for python_requires in https://docs.conan.io/en/latest/extending/python_requires.html.

The approach to use python_requires to implement a generator is basically (code not tested, just the idea):

• Create a generator like class inside a python_require, something like:

  from conan import ConanFile
  class MyGenerator:
         def __init__(self, conanfile):
                 self._conanfile = conanfile
         def generate(self):
                 for dep in self._conanfile.dependencies....
                        ...
                 # save files to be used in the build
  class MyTool(ConanFile):
         name = "tool"
         version = "0.1"
  

• Reuse it like:

  from conan import ConanFile
  class Pkg(ConanFile):
         python_requires = "tool/0.1"
         def generate(self):
               generator = self.python_requires["tool"].module.MyGenerator(self)
               generator.generate()