VirtualBuildEnv

VirtualBuildEnv is a generator that produces a conanbuildenv .bat, .ps1 or .sh script containing the environment variables of the build time context:

• From the self.buildenv_info of the direct tool_requires in “build” context.

• From the self.runenv_info of the transitive dependencies of those tool_requires.

It 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()

Generated files

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

• conanbuildenv-release-x86_64.(bat|ps1|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|ps1|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|ps1|sh) script will call the Debug one.

• deactivate_conanbuild.(bat|ps1|sh): Accumulates the deactivation calls defined in the above conanbuild.(bat|ps1|sh). This file should only be called after the accumulated activate has been called first.

Note

To create .ps1 files required for Powershell it is necessary to set to True the following conf: tools.env.virtualenv:powershell.

Note

Disabling the automatic generation of these files for consumers can be achieved by passing --envs-generation=false to the conan install command. This feature is experimental and subject to change, and disabling this file can lead to unexpected build errors, if for example tool_requires are used. Ensure they are not needed if the generation is disabled.

Reference

class VirtualBuildEnv(conanfile, auto_generate=False)

Calculates the environment variables of the build time context and produces a conanbuildenv .bat or .sh script

• environment()

  Returns an Environment object containing the environment variables of the build context.

  • Returns:

    an Environment object instance containing the obtained variables.

• vars(scope=’build’)

  • Parameters:

    scope – Scope to be used.

    Returns:

    An EnvVars instance containing the computed environment variables.

• generate(scope=’build’)

  Produces the launcher scripts activating the variables for the build context.

  • Parameters:

    scope – Scope to be used.