From thread: 'Why did my changes get reverted?' July 19, 2011.

>> Maybe we can add linker and optimizer params to theano.function, so
>> that the API makes it possible to avoid specifying a mode altogether?
>
> That seems reasonable. We just have to be careful about the interactions
> between those params.
> --
> Pascal
>

How about they all default to None.

Specifying mode 'deactivates' linker and optimizer.
Specifying linker or optimizer 'deactivates' mode.

'deactivated' params must be None or a TypeError exception is raised?