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, env="conanbuild"):
self.run()
is a helper to run system commands and throw exceptions when errors occur,
so that command errors do not pass unnoticed. It is just a wrapper for
subprocess.call()
.
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.
The command
can be specified as a string which is passed to the system shell.
Alternatively it can be specified as a sequence of strings, the first of which is
interpreted as the name of the program to be executed and the remaining ones are passed as
arguments. Unless you are relying on shell-specific features such as redirection or command
substitution, providing a sequence of strings is generally preferred as it allows Conan to
take care of any required escaping and quoting of arguments (e.g. to permit spaces in file
names).
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 asix.StringIO()
:
from six import StringIO # Python 2 and 3 compatible mybuf = StringIO() self.run("mycommand", output=mybuf) self.output.warn(mybuf.getvalue())
- output (Optional, Defaulted to
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. Ifignore_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 aRunEnvironment
, 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 usingwin_bash
parameter. This might come handy when you don’t want to create a fresh user session for running the command.env (Optional, Defaulted to
conanbuild
): the environment or list of environment activations scripts to pre-pend to the givencommand
. IfNone
, no environment will be pre-pended.
Requiring a Conan version for the recipe
Available since: 1.28.0
A required Conan version can be declared in the conanfile.py using required_conan_version
to
throw an error when the Conan version installed does not meet the criteria established by the
variable. To add required_conan_version
to a conanfile.py just declare it before the recipe
class definition:
from conans import ConanFile required_conan_version = ">=1.27.1" class Pkg(ConanFile): settings = "os", "compiler", "arch", "build_type" ...
It is also possible to declare required_conan_version
at configuration level for the whole client
adding it to the conan.conf file.