mvpa2.base.externals.exists(dep, force=False, raise_=False, issueWarning=None, exception=<type 'exceptions.RuntimeError'>)

Test whether a known dependency is installed on the system.

This method allows us to test for individual dependencies without testing all known dependencies. It also ensures that we only test for a dependency once.


dep : string or list of string

The dependency key(s) to test.

force : boolean

Whether to force the test even if it has already been performed.

raise_ : boolean, str

Whether to raise an exception if dependency is missing. If True, it is still conditioned on the global setting MVPA_EXTERNALS_RAISE_EXCEPTION, while would raise exception if missing despite the configuration if ‘always’.

issueWarning : string or None or True

If string, warning with given message would be thrown. If True, standard message would be used for the warning text.

exception : exception, optional

What exception to raise. Defaults to RuntimeError