make cfg.channels forbidden

[robertoostenveld]

Is your feature request related to a problem? Please describe.

I noticed a user to specify cfg.channels rather than cfg.channel, where the channel selection was subsequently ignored. This lead to unexpected results further down in the analysis.

Describe the solution you'd like

Using ft_checkconfig we could make cfg.channels forbidden in all high-level functions.

Describe alternatives you've considered

We could also make use the ft_checkconfig renamed option and rename channels into channel. Since channels was never used, I am not in favor of that.

[schoffelen]

I agree. Better make the user aware of the fact that they should pay attention to the proper spelling of options, rather than automatic fixes for often unintended typos

[robertoostenveld]

The same thing just happened for cfg.method rather than cfg.interpmethod in ft_sourceinterpolate.

[schoffelen]

regarding method: there's also a cfg.planarmethod :). Would it not make sense to revert those instances back to plain cfg.method? in case the function does not have different methods as option, it would streamline the option naming scheme in general.

[schoffelen]

BTW, regarding channels vs. channel: why is it called cfg.trials, and not cfg.trial?

[robertoostenveld]

there is also invmethod, pairmethod, mvarmethod, submethod, refmethod, cohmethod, powmethod, supmethod, fwhmmethod, projmethod, spmmethod, and others.

For some it is a sub-specification, for others it is the consequence of code refactoring in the past, e.g. ft_megplanar was once part of the same high-level function as ft_meginterpolate.

For functions that have a single unambiguous method, like ft_sourceinterpolate, I do prefer cfg.method over the peculiar methods that are now used.

[schoffelen]

pairmethod?

[robertoostenveld]

regarding interpmethod: I see in ft_sourceplot that when cfg.method=surface you can specify cfg.projmethod, which later in the code is translated into tmpcfg.interpmethod.

I think that is too big to be solved together with this issue. We can keep it in mind for later.