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 β€œlib” and β€œbin” 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.