Conan: [bug] Inconsistent type of self.version in conanfile methods with different commands

[rddesmond]

Some commands translate the conanfile version into a conans.model.version.Version object before it is accessible to the method (conan create and conan export_pkg). A few commands return it as a str (conan install). Others return it as a Version if conan.lock file is present and a str otherwise (conan source, conan graph lock, conan build, conan package, conan import).

This inconsistency leads to recipes that work in a conan create workflow, but fail if the build process is split over multiple steps. (I found this while working on a script to localize all of the sources so that they could be security scanned before building them.)

from conans import ConanFile

class VersionTest(ConanFile):
    version = "1.1.1"
    name = 'VersionTest'

    def source(self):
       minor = self.version.minor()

This is used successfully in conan create, but fails during conan source with:

ERROR: Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/conans/errors.py", line 34, in conanfile_exception_formatter
    yield
  File "/usr/local/lib/python3.6/site-packages/conans/client/source.py", line 143, in _run_source
    conanfile.source()
  File "/home/rdesmond/Desktop/output/version_test/exception/conanfile.py", line 8, in source
    minor = self.version.minor()
AttributeError: 'str' object has no attribute 'minor'

NOTE: If a conan.lock file is present (such as if conan install is run) conan source will succeed.

Environment Details (include every applicable attribute)

• Operating System+version: Centos 7.7.1908
• Compiler+version: n/a
• Conan version: 1.23.0
• Python version: 2.7.5

Attachments

version_test.tar.gz contains the above and a recipe that invokes has method (except the new set_*) and prints the type of self.version. I used it to test.

[danimtb]

Hi @rddesmond and thanks a lot for the report.

Yes, I can confirm this is happening and it should be fixed. The conanfile.version filed should be always a string for the user interface inside recipes and conans.model.version.Version should not be used as it is an internal implementation.

I'd recommend you to use the public interface class tools.Version instead: https://docs.conan.io/en/latest/reference/tools.html#tools-version that has a similar interface.

[rddesmond]

Thanks for the triage! It's probably reasonable to expect that self.version can be evaluated as a string, but could be varying types, though yeah, didn't expect that to change conditionally as it did. Good call-out to the tool. I needed to learn that model.version.Version.minor != tools.Version.minor (given a version 1.2.0, minor() returns 1.2 and 2 for the different classes, respectively), but it's useful and the right answer.

[memsharded]

The thing is that self.version is intended to be always a string.
At some point in one of the latest unrelated changed, we internally assigned a Version object. This will be changed, it is not documented anywhere, self.version.minor is not part of the public api.

We will revert that change so self.version is always a string. If you want to do some version processing, you will be able wrapping it like Version(self.version), being Version the documented helper, not the internal one.

[rddesmond]

Makes sense. Thanks for all the hard work. Conan continues to make everything in the c++ stack so much easier.

[memsharded]

Hi @rddesmond

We have proposed a fix in https://github.com/conan-io/conan/pull/6782, but then realized that this change has a potential to break other users, and we certainly don't want to do this, so it will need to wait until Conan 2.0.

So at the moment, I would recommend you the following:

• Assume that self.version is always a string.
• When you want to do comparisons and access members, do a Version(self.version) first.
• This should work in all methods and scenarios, even when self.version is already the internal Version object, because that can be processed too.
• Make sure that that Version is conans.tools.Version (documented in https://docs.conan.io/en/latest/reference/tools.html?tools-version#tools-version) and not the internal one.

Thanks!