Re: Shift selection using interactive spec

[Stefan Monnier]

>>> I think it would be more elegant to split this up into two pieces: a
>>> variable this-single-command-shift-translated that says whether shift
>>> translation occurred, and a function shift-translation-handler that
>>> temporarily sets transient mark mode.  Both would be available to
>>> elisp programs.
>> 
>> Yes, that part is fine.
>> 
>>> The new interactive spec code ^ would then call
>>> shift-translation-handler if this-single-command-shift-translated is
>>> non-nil, but elisp programs could accomplish this just as easily via
>>> (if this-single-command-shift-translated ...).
>> 
>> No, the `if' test should be done inside the function.

> What is the rationale for this?  It seems clear that

Calling the function just means "I'm a movement command and would like
to follow the new select-on-shift behavior".

Then the function can decide on what actually happens when.

>   "Extend the temporary region highlighting for the next command"

> is a neater and more self-contained task for a function than

>   "Extend the temporary region highlighting for the next command, but
>    only if this-single-command-shift-translated is non-nil; otherwise,
>    do nothing"

The docstring of the function would be more like

  "Handle the mark selection for movement commands."


-- Stefan