/usr/share/pyshared/gnatpython/env.py is in python-gnatpython 54-3.
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# #
# ENV.PY #
# #
# Copyright (C) 2008 - 2011 Ada Core Technologies, Inc. #
# #
# This program is free software: you can redistribute it and/or modify #
# it under the terms of the GNU General Public License as published by #
# the Free Software Foundation, either version 3 of the License, or #
# (at your option) any later version. #
# #
# This program is distributed in the hope that it will be useful, #
# but WITHOUT ANY WARRANTY; without even the implied warranty of #
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the #
# GNU General Public License for more details. #
# #
# You should have received a copy of the GNU General Public License #
# along with this program. If not, see <http://www.gnu.org/licenses/> #
# #
############################################################################
"""Global environment handling
This package provide a class called Env used to store global information. Env
is a singleton so there is in fact only one instance.
Here is a description of the functionalities provided by the class:
* host, target information retrieval/setting:
>>> from gnatpython.env import Env
>>> e = Env ()
>>> print e.target
platform: x86-linux
machine: barcelona
is_hie: False
is_host: True
triplet: i686-pc-linux-gnu
OS
name: linux
version: suse10.3
is_bareboard: False
CPU
name: x86
bits: 32
endian: little
>>> e.set_target ('ppc-vxw')
>>> print e.target.os.name
vxworks
>>> print e.target.os.version
5.5
* make some info global
>>> e = Env ()
>>> d = Env ()
>>> e.example_of_global_info = 'hello'
>>> print d.example_of_global_info
hello
* restoring/saving complete environment, including environment variables and
current dir
>>> e = Env ()
>>> e.example = 'hello'
>>> e.store ('./saved_env')
>>> ^D
$ gnatpython
>>> from gnatpython.env import Env
>>> e = Env ()
>>> e.restore ('./saved_env')
>>> print e.example
hello
"""
from gnatpython.arch import Arch
import pickle
import os
def putenv(key, value):
"""Portable version of os.putenv"""
# When a variable is set by os.putenv, os.environ is not updated;
# this is a problem, as Env and ex.Run use os.environ to store the
# current environment or to spawn a process. This limitation is
# documented in the Python Library Reference:
# environ
# A mapping object representing the string environment. For
# example, environ['HOME'] is the pathname of your home directory
# (on some platforms), and is equivalent to getenv("HOME") in C.
#
# This mapping is captured the first time the os module is
# imported, typically during Python startup as part of
# processing site.py. Changes to the environment made after
# this time are not reflected in os.environ, except for
# changes made by modifying os.environ directly.
#
# If the platform supports the putenv() function, this
# mapping may be used to modify the environment as well as
# query the environment. putenv() will be called
# automatically when the mapping is modified. Note: Calling
# putenv() directly does not change os.environ, so it's
# better to modify os.environ.
# ...For this reason, os.environ is prefered to os.putenv here.
os.environ[key] = value
def getenv(key, default=None):
"""Portable version of os.getenv"""
# For the reason documented in putenv, and for consistency, it is better
# to use os.environ instead of os.getenv here.
if key in os.environ:
return os.environ[key]
else:
return default
class Env (object):
"""Environment Handling
ATTRIBUTES
build: default system (autodetected)
host: host system
target: target system
is_cross: true if we are in a cross environment
REMARKS
build, host and target attributes are instances of Arch class. Do
pydoc gnatpython.arch for more information
"""
# class variable that holds the current environment
__instance = {}
# class variable that holds the stack of saved environments state
__context = []
def __init__(self):
"""Env constructor
PARAMETERS
None
RETURN VALUE
A Env instance
REMARKS
On first instantiation, build attribute will be computed and host
and target set to the build attribute.
"""
if 'build' not in Env.__instance:
self.is_cross = False
self.build = Arch()
self.host = self.build
self.target = self.host
self.environ = None
self.cwd = None
self.main_options = None # Command line switches
def __getattr__(self, name):
return Env.__instance[name]
def __setattr__(self, name, value):
Env.__instance[name] = value
def set_host(self, host_name=None, host_version=None):
"""Set host platform
PARAMETERS
host_name: a string that identify the system to be considered as the
host. If None then host is set to the build one (the
autodetected platform).
host_version: a string containing the system version. If set to None
the version is either a default or autodetected when
possible
RETURN VALUE
None
REMARKS
None
"""
if host_name is not None:
self.host = Arch(platform_name=host_name,
is_host=True,
version=host_version)
else:
self.host = self.build
if self.target != self.host:
self.is_cross = True
else:
self.is_cross = False
def set_target(self, target_name=None, target_version=None,
target_machine=None):
"""Set target platform
PARAMETERS
host_name: a string that identify the system to be considered as the
host. If None then host is set to the host one.
host_version: a string containing the system version. If set to None
the version is either a default or autodetected when
possible
RETURN VALUE
None
REMARKS
None
"""
if target_name is not None:
self.target = Arch(platform_name=target_name,
version=target_version,
machine=target_machine)
else:
self.target = self.host
if self.target != self.host:
self.is_cross = True
else:
self.is_cross = False
def get_attr(self, name, default_value=None, forced_value=None):
"""Return an attribute value
PARAMETERS
name: name of the attribute to check. Name can contain '.'
default_value: returned value if forced_value not set and the
attribute does not exist
forced_value: if not None, this is the return value
RETURN VALUE
the attribute value
REMARKS
This function is useful to get the value of optional functions
parameters whose default value might depend on the environment.
"""
if forced_value is not None:
return forced_value
attributes = name.split('.')
result = self
for a in attributes:
if not hasattr(result, a):
return default_value
else:
result = getattr(result, a)
if result is None or result == "":
return default_value
return result
def store(self, filename=None):
"""Save environment into memory or file
PARAMETERS
filename: a string containing the path of the filename in which the
environement will be saved. If set to None the environment is
saved into memory in a stack like structure.
RETURN VALUE
None
"""
# Store environment variables
self.environ = os.environ.copy()
# Store cwd
self.cwd = os.getcwd()
if filename is None:
Env.__context.append(pickle.dumps(Env.__instance))
else:
fd = open(filename, 'w+')
pickle.dump(Env.__instance, fd)
fd.close()
def restore(self, filename=None):
"""Restore environment from memory or a file
PARAMETERS
filename: a string containing the path of the filename from which
the environement will be restored. If set to None the environment
is pop the last saved one
RETURN VALUE
None
"""
if filename is None:
# We are restoring from memory. In that case, just double-check
# that we did store the Env object in memory beforehand (using
# the store method).
assert (self.environ is not None)
if filename is None and Env.__context:
Env.__instance = pickle.loads(Env.__context[-1])
Env.__context = Env.__context[:-1]
elif filename is not None:
fd = open(filename, 'r')
Env.__instance = pickle.load(fd)
fd.close()
else:
return
# Restore environment variables value
os.environ = self.environ.copy()
# Restore current directory
os.chdir(self.cwd)
@classmethod
def add_path(cls, path, append=False):
"""Set a path to PATH environment variable
PARAMETERS
path: path to add
append: if True append, otherwise prepend. Default is prepend
RETURN VALUE
None
REMARKS
None
"""
if append:
os.environ['PATH'] += os.path.pathsep + path
else:
os.environ['PATH'] = path + os.path.pathsep + os.environ['PATH']
@classmethod
def add_search_path(cls, env_var, path, append=False):
"""Add a path to the env_var search paths
PARAMETERS
env_var: the environment variable name
(e.g. PYTHONPATH, LD_LIBRARY_PATH, ...)
path: path to add
append: if True append, otherwise prepend. Default is prepend
RETURN VALUE
None
REMARKS
None
"""
if not env_var in os.environ:
os.environ[env_var] = path
else:
if append:
os.environ[env_var] += os.path.pathsep + path
else:
os.environ[env_var] = path + os.path.pathsep + \
os.environ[env_var]
def add_dll_path(self, path, append=False):
"""Add a path to the dynamic libraries search paths
PARAMETERS
path: path to add
append: if True append, otherwise prepend. Default is prepend
RETURN VALUE
None
REMARKS
None
"""
# On most platforms LD_LIBRARY_PATH is used. For others use:
env_var_name = {'windows': 'PATH',
'hp-ux': 'SHLIB_PATH',
'darwin': 'DYLD_LIBRARY_PATH'}
env_var = env_var_name.get(
self.host.os.name.lower(),
'LD_LIBRARY_PATH')
self.add_search_path(env_var, path, append)
@property
def discriminants(self):
"""Compute discriminants"""
discs = [self.target.platform, self.target.triplet,
self.target.cpu.endian + '-endian',
self.target.cpu.name,
self.target.os.name,
self.target.os.name + '-' + self.target.os.version,
self.host.os.name + '-host']
if not self.is_cross:
discs.append('native')
if self.target.cpu.bits == 64:
discs.append('64bits')
if self.target.os.name.lower() == 'windows':
discs.append('NT')
return discs
@property
def tmp_dir(self):
return os.environ.get('TMPDIR',
os.environ.get('TMP', '/tmp'))
if __name__ == "__main__":
print Env().host
print "discs: " + ", ".join(Env().discriminants)
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