Queries the environment variables. The first variant returns the
value of a specific variable or zero if it doesn't exist in the
environment. The second variant returns the whole environment as a
mapping. Destructive operations on the mapping will not affect the
internal environment representation.
A cached copy of the real environment is kept to make this
function quicker. If the optional flag force_update is nonzero
then the real environment is queried and the cache is updated from
it. That can be necessary if the environment changes through other
means than putenv , typically from a C-level library.
Variable names and values cannot be wide strings nor contain
'\0' characters. Variable names also cannot contain
'=' characters.
MasterObject()->get_compilation_handler()