VirtualBuildEnv

Warning

These tools are still experimental (so subject to breaking changes) but with very stable syntax. We encourage the usage of it to be prepared for Conan 2.0.

The VirtualBuildEnv generator can be used by name in conanfiles:

conanfile.py
class Pkg(ConanFile):
    generators = "VirtualBuildEnv"
conanfile.txt
[generators]
VirtualBuildEnv

And it can also be fully instantiated in the conanfile generate() method:

conanfile.py
from conan import ConanFile
from conan.tools.env import VirtualBuildEnv

class Pkg(ConanFile):
    settings = "os", "compiler", "arch", "build_type"
    requires = "zlib/1.2.11", "bzip2/1.0.8"

    def generate(self):
        ms = VirtualBuildEnv(self)
        ms.generate()

When the VirtualBuildEnv generator is used, calling conan install will generate a conanbuildenv .bat or .sh script containing environment variables of the build time environment.

That information is collected from the direct tool_requires in “build” context recipes from the self.buildenv_info definition plus the self.runenv_info of the transitive dependencies of those tool_requires.

This generator (for example the invocation of conan install cmake/3.20.0@ -g VirtualBuildEnv --build-require) will create the following files:

  • conanbuildenv-release-x86_64.(bat|sh): This file contains the actual definition of environment variables like PATH, LD_LIBRARY_PATH, etc, and any other variable defined in the dependencies buildenv_info corresponding to the build context, and to the current installed configuration. If a repeated call is done with other settings, a different file will be created. After the execution or sourcing of this file, a new deactivation script will be generated, capturing the current environment, so the environment can be restored when desired. The file will be named also following the current active configuration, like deactivate_conanbuildenv-release-x86_64.bat.

  • conanbuild.(bat|sh): Accumulates the calls to one or more other scripts, in case there are multiple tools in the generate process that create files, to give one single convenient file for all. This only calls the latest specific configuration one, that is, if conan install is called first for Release build type, and then for Debug, conanbuild.(bat|sh) script will call the Debug one.

  • deactivate_conanbuild.(bat|sh): Accumulates the deactivation calls defined in the above conanbuild.(bat|sh). This file should only be called after the accumulated activate has been called first.

Constructor

def __init__(self, conanfile):

  • conanfile: the current recipe object. Always use self.

generate()

def generate(self, scope="build"):

Parameters:

  • scope (Defaulted to "build"): Add the launcher automatically to the conanbuild launcher. Read more in the Environment documentation.