Python requires

It is possible to reuse python code existing in other conanfile.py recipes with the python_requires functionality, doing something like:

from conans import ConanFile

class Pkg(ConanFile):
    python_requires = "pyreq/0.1@user/channel"

    def build(self):
        v = self.python_requires["pyreq"].module.myvar # myvar defined in pyreq's conanfile.py
        f = self.python_requires["pyreq"].module.myfunct() # myfunct defined in pyreq's conanfile.py
        self.output.info("%s,%s" % (v, f))

See this section: Python requires: reusing python code in recipes

Output and Running

Output contents

Use the self.output to print contents to the output.

self.output.success("This is a good, should be green")
self.output.info("This is a neutral, should be white")
self.output.warn("This is a warning, should be yellow")
self.output.error("Error, should be red")
self.output.rewrite_line("for progress bars, issues a cr")

Check the source code. You might be able to produce different outputs with different colors.

Running commands

run(self, command, output=True, cwd=None, win_bash=False, subsystem=None, msys_mingw=True,
    ignore_errors=False, run_environment=False, with_login=True):

self.run() is a helper to run system commands and throw exceptions when errors occur, so that command errors are do not pass unnoticed. It is just a wrapper for os.system()

When the environment variable CONAN_PRINT_RUN_COMMANDS is set to true (or its equivalent print_run_commands conan.conf configuration variable, under [general]) then all the invocations of self.run() will print to output the command to be executed.

Optional parameters:

  • output (Optional, Defaulted to True) When True it will write in stdout.

    You can pass any stream that accepts a write method like a six.StringIO():

    from six import StringIO  # Python 2 and 3 compatible
mybuf = StringIO()
self.run("mycommand", output=mybuf)
self.output.warn(mybuf.getvalue())

  • cwd (Optional, Defaulted to . current directory): Current directory to run the command.

  • win_bash (Optional, Defaulted to False): When True, it will run the configure/make commands inside a bash.

  • subsystem (Optional, Defaulted to None will autodetect the subsystem): Used to escape the command according to the specified subsystem.

  • msys_mingw (Optional, Defaulted to True) If the specified subsystem is MSYS2, will start it in MinGW mode (native windows development).

  • ignore_errors (Optional, Defaulted to False). This method raises an exception if the command fails. If ignore_errors=True, it will not raise an exception. Instead, the user can use the return code to check for errors.

  • run_environment (Optional, Defaulted to False). Applies a RunEnvironment, so the environment variables PATH, LD_LIBRARY_PATH and DYLIB_LIBRARY_PATH are defined in the command execution adding the values of the “lib” and “bin” folders of the dependencies. Allows executables to be easily run using shared libraries from its dependencies.

  • with_login (Optional, Defaulted to True): Pass the --login flag to bash command when using win_bash parameter. This might come handy when you don’t want to create a fresh user session for running the command.