Environment¶
Environment
is a generic class that helps to define modifications to the environment variables.
This class is used by other tools like the conan.tools.gnu Autotools helpers and
the VirtualBuildEnv and VirtualRunEnv
generator. It is important to highlight that this is a generic class, to be able to use it, a specialization
for the current context (shell script, bat file, path separators, etc), a EnvVars
object needs to be obtained
from it.
Variable declaration¶
from conan.tools.env import Environment
def generate(self):
env = Environment()
env.define("MYVAR1", "MyValue1") # Overwrite previously existing MYVAR1 with new value
env.append("MYVAR2", "MyValue2") # Append to existing MYVAR2 the new value
env.prepend("MYVAR3", "MyValue3") # Prepend to existing MYVAR3 the new value
env.remove("MYVAR3", "MyValue3") # Remove the MyValue3 from MYVAR3
env.unset("MYVAR4") # Remove MYVAR4 definition from environment
# And the equivalent with paths
env.define_path("MYPATH1", "path/one") # Overwrite previously existing MYPATH1 with new value
env.append_path("MYPATH2", "path/two") # Append to existing MYPATH2 the new value
env.prepend_path("MYPATH3", "path/three") # Prepend to existing MYPATH3 the new value
The “normal” variables (the ones declared with define
, append
and prepend
) will be appended with a space,
by default, but the separator
argument can be provided to define a custom one.
The “path” variables (the ones declared with define_path
, append_path
and prepend_path
) will be appended
with the default system path separator, either :
or ;
, but it also allows defining which one.
Composition¶
Environments can be composed:
from conan.tools.env import Environment
env1 = Environment()
env1.define(...)
env2 = Environment()
env2.append(...)
env1.compose_env(env2) # env1 has priority, and its modifications will prevail
Obtaining environment variables¶
You can obtain an EnvVars
object with the vars()
method like this:
from conan.tools.env import Environment
def generate(self):
env = Environment()
env.define("MYVAR1", "MyValue1")
envvars = env.vars(self, scope="build")
# use the envvars object
The default scope
is equal "build"
, which means that if this envvars
generate a script to
activate the variables, such script will be automatically added to the conanbuild.sh|bat
one, for
users and recipes convenience. Conan generators use build
and run
scope, but it might be possible
to manage other scopes too.
Environment definition¶
There are some other places where Environment
can be defined and used:
In recipes
package_info()
method, in newself.buildenv_info
andself.runenv_info
, this environment will be propagated viaVirtualBuildEnv
andVirtualRunEnv
respectively to packages depending on this recipe.In generators like
AutootoolsDeps
,AutotoolsToolchain
, that need to define environment for the current recipe.In profiles
[buildenv]
section.In profiles
[runenv]
section.
The definition in package_info()
is as follow, taking into account that both self.buildenv_info
and self.runenv_info
are objects of Environment()
class.
from conan import ConanFile
class App(ConanFile):
name = "mypkg"
version = "1.0"
settings = "os", "arch", "compiler", "build_type"
def package_info(self):
# This is information needed by consumers to build using this package
self.buildenv_info.append("MYVAR", "MyValue")
self.buildenv_info.prepend_path("MYPATH", "some/path/folder")
# This is information needed by consumers to run apps that depends on this package
# at runtime
self.runenv_info.define("MYPKG_DATA_DIR", os.path.join(self.package_folder,
"datadir"))
Reference¶
- class Environment¶
Generic class that helps to define modifications to the environment variables.
- dumps()¶
- Returns:
A string with a profile-like original definition, not the full environment values
- define(name, value, separator=' ')¶
Define name environment variable with value value
- Parameters:
name – Name of the variable
value – Value that the environment variable will take
separator – The character to separate appended or prepended values
- unset(name)¶
clears the variable, equivalent to a unset or set XXX=
- Parameters:
name – Name of the variable to unset
- append(name, value, separator=None)¶
Append the value to an environment variable name
- Parameters:
name – Name of the variable to append a new value
value – New value
separator – The character to separate the appended value with the previous value. By default it will use a blank space.
- append_path(name, value)¶
Similar to “append” method but indicating that the variable is a filesystem path. It will automatically handle the path separators depending on the operating system.
- Parameters:
name – Name of the variable to append a new value
value – New value
- prepend(name, value, separator=None)¶
Prepend the value to an environment variable name
- Parameters:
name – Name of the variable to prepend a new value
value – New value
separator – The character to separate the prepended value with the previous value
- prepend_path(name, value)¶
Similar to “prepend” method but indicating that the variable is a filesystem path. It will automatically handle the path separators depending on the operating system.
- Parameters:
name – Name of the variable to prepend a new value
value – New value
- remove(name, value)¶
Removes the value from the variable name.
- Parameters:
name – Name of the variable
value – Value to be removed.
- compose_env(other)¶
Compose an Environment object with another one.
self
has precedence, the “other” will add/append if possible and not conflicting, butself
mandates what to do. Ifself
hasdefine()
, without placeholder, that will remain.- Parameters:
other (class:Environment) – the “other” Environment
- vars(conanfile, scope='build')¶
Return an EnvVars object from the current Environment object :param conanfile: Instance of a conanfile, usually
self
in a recipe :param scope: Determine the scope of the declared variables. :return:
- deploy_base_folder(package_folder, deploy_folder)¶
Make the paths relative to the deploy_folder