CtypesEnviron

(class from pyomo.common.env)

class pyomo.common.env.CtypesEnviron(**kwds)

Bases: object

A context manager for managing environment variables

This class provides a simplified interface for consistently setting and restoring environment variables, with special handling to ensure consistency with the C Runtime Library environment on Windows platforms.

os.environ reflects the current python environment variables, and will be passed to subprocesses. However, it does not reflect the C Runtime Library (MSVCRT) environment on Windows platforms. This can be problemmatic as DLLs loaded through the CTYPES interface will see the MSVCRT environment and not os.environ. This class provides a way to manage environment variables and pass changes to both os.environ and the MSVCRT runtime.

This class implements a context manager API, so that clients can temporarily change - and then subsequently restore - the environment.

>>> os.environ['TEMP_ENV_VAR'] = 'original value'
>>> print(os.environ['TEMP_ENV_VAR'])
original value

>>> with CtypesEnviron(TEMP_ENV_VAR='temporary value'):
...    print(os.environ['TEMP_ENV_VAR'])
temporary value

>>> print(os.environ['TEMP_ENV_VAR'])
original value

__init__(**kwds)

Methods

__init__(**kwds)
restore()	Restore the environment to the original state

Attributes

DLLs

Member Documentation

restore()

Restore the environment to the original state

This restores all environment variables modified through this object to the state they were in before this instance made any changes. Note that any changes made directly to os.environ outside this instance will not be detected / undone.