How to capture package version from SCM: git

The Git() helper from tools can be used to capture data from the Git repo in which the conanfile.py recipe resides, and use it to define the version of the Conan package.

from conans import ConanFile, tools

def get_version():
    git = tools.Git()
    try:
        return "%s_%s" % (git.get_branch(), git.get_revision())
    except:
        return None

class HelloConan(ConanFile):
    name = "Hello"
    version = get_version()

    def build(self):
        ...

In this example, the package created with conan create will be called Hello/branch_commit@user/channel. Note that get_version() returns None if it is not able to get the Git data. This is necessary when the recipe is already in the Conan cache, and the Git repository may not be there. A value of None makes Conan get the version from the metadata.

How to capture package version from SCM: svn

The SVN() helper from tools can be used to capture data from the subversion repo in which the conanfile.py recipe resides, and use it to define the version of the Conan package.

from conans import ConanFile, tools

def get_svn_version(version):
    try:
        scm = tools.SVN()
        revision = scm.get_revision()
        branch = scm.get_branch() # Delivers e.g trunk, tags/v1.0.0, branches/my_branch
        branch = branch.replace("/","_")
        if scm.is_pristine():
            dirty = ""
        else:
            dirty = ".dirty"
        return "%s-%s+%s%s" % (version, revision, branch, dirty) # e.g. 1.2.0-1234+trunk.dirty
    except Exception:
        return None

class HelloLibrary(ConanFile):
    name = "Hello"
    version = get_svn_version("1.2.0")

    def build(self):
        ...

In this example, the package created with conan create will be called Hello/generated_version@user/channel. Note that get_svn_version() returns None if it is not able to get the subversion data. This is necessary when the recipe is already in the Conan cache, and the subversion repository may not be there. A value of None makes Conan get the version from the metadata.

How to capture package version from text or build files

It is common that a library version number would be already encoded in a text file, build scripts, etc. As an example, let’s assume we have the following library layout, and that we want to create a package from it:

conanfile.py
CMakeLists.txt
src
   hello.cpp
   ...

The CMakeLists.txt will have some variables to define the library version number. For simplicity, let’s also assume that it includes a line such as the following:

cmake_minimum_required(VERSION 2.8)
set(MY_LIBRARY_VERSION 1.2.3) # This is the version we want
add_library(hello src/hello.cpp)

Typically, our conanfile.py package recipe will include:

class HelloConan(ConanFile):
    name = "Hello"
    version = "1.2.3"

This usually requires very little maintenance, and when the CMakeLists version is bumped, so is the conanfile.py version. However, if you only want to have to update the CMakeLists.txt version, you can extract the version dynamically, using:

from conans import ConanFile
from conans.tools import load
import re

def get_version():
    try:
        content = load("CMakeLists.txt")
        version = re.search(b"set\(MY_LIBRARY_VERSION (.*)\)", content).group(1)
        return version.strip()
    except Exception as e:
        return None

class HelloConan(ConanFile):
    name = "Hello"
    version = get_version()

Even if the CMakeLists.txt file is not exported to the local cache, it will still work, as the get_version() function returns None when it is not found, and then takes the version number from the package metadata (layout).