Bases: object
The PathManager defines a registry class for path locations
The PathManager defines a class very similar to the
CachedFactory class; however it does not register type
constructors. Instead, it registers instances of
PathData (or ExecutableData). These
contain the resolved path to the directory object under which the
PathData object was registered. We do not use
the PyUtilib register_executable and registered_executable
functions so that we can automatically include Pyomo-specific
locations in the search path (namely the PYOMO_CONFIG_DIR).
Users will generally interact with this class through global
instances of this class (pyomo.common.Executable and
pyomo.common.Library).
Users are not required or expected to register file names with the
PathManager; they will be automatically registered
upon first use. Generally, users interact through the path()
and available() methods:
>>> from pyomo.common import Executable
>>> if Executable('demo_exec_file').available():
... loc = Executable('demo_exec_file').path()
... print(os.path.isfile(loc))
True
>>> print(os.access(loc, os.X_OK))
True
For convenience, available() and path() are
available by casting the PathData object requrned
from Executable or Library to either a bool or str:
>>> if Executable('demo_exec_file'):
... cmd = "%s --help" % Executable('demo_exec_file')
The PathManager caches the location / existence of
the target directory entry. If something in the environment changes
(e.g., the PATH) or the file is created or removed after the first
time a client queried the location or availability, the
PathManager will return incorrect information. You can cause
the PathManager to refresh its cache by calling
rehash() on either the PathData (for the
single file) or the PathManager to refresh the
cache for all files:
>>> # refresh the cache for a single file
>>> Executable('demo_exec_file').rehash()
>>> # or all registered files
>>> Executable.rehash()
The Executable singleton looks for executables in the system
PATH and in the list of directories specified by the pathlist
attribute. Executable.pathlist defaults to a list containing the
os.path.join(pyomo.common.envvar.PYOMO_CONFIG_DIR, 'bin').
The Library singleton looks for executables in the system
LD_LIBRARY_PATH, PATH and in the list of directories
specified by the pathlist attribute. Library.pathlist
defaults to a list containing the
os.path.join(pyomo.common.envvar.PYOMO_CONFIG_DIR, 'lib').
Users may also override the normal file resolution by explicitly
setting the location using set_path():
>>> Executable('demo_exec_file').set_path(os.path.join(
... pyomo.common.envvar.PYOMO_CONFIG_DIR, 'bin', 'demo_exec_file'))
Explicitly setting the path is an absolute operation and will
set the location whether or not that location points to an actual
file. Additionally, the explicit location will persist
through calls to rehash(). If you wish to remove the explicit
executable location, call set_path(None):
>>> Executable('demo_exec_file').set_path(None)
The Executable singleton uses ExecutableData, an
extended form of the PathData class, which provides the
executable property as an alias for path() and
set_path():
>>> loc = Executable('demo_exec_file').executable
>>> print(os.path.isfile(loc))
True
>>> Executable('demo_exec_file').executable = os.path.join(
... pyomo.common.envvar.PYOMO_CONFIG_DIR, 'bin', 'demo_exec_file')
>>> Executable('demo_exec_file').executable = None
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__init__(finder, dataClass)[source]
Methods
__init__(finder, dataClass)
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rehash()
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Requery the location of all registered executables |
Member Documentation
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rehash()[source]
Requery the location of all registered executables
This method derives its name from the csh command of the same
name, which rebuilds the hash table of executables reachable
through the PATH.