Re: Standard check before creating large num of frames

[Tino Calancha]

On Thu, 15 Sep 2016, Stefan Monnier wrote:

> > several functions might create new frames.  In particular when
> > `pop-up-frames' is non-nil, `display-buffer' creates a new frame.
> > Creating a lot of new frames might be expensive.
>
> > Some functions may ask for user confirmation before creating an many
> > frames.  For instance, see `ibuffer-do-view-1': this function ask for
> > confirmation before creating > 3 frames.  IMO, it's good if each
> > function creating a large number of frames do a similar check.  We might
> > add a new option, for instance 'max-number-of-frames' or
> > 'frame-max-number':
>
> I get the impression that setting pop-up-frames will inevitably lead to
> many more frames than 3.  IOW setting pop-up-frames non-nil is already
> a way to say that you're OK with having many frames.
That was an example: that's why i said 'in particular'.
Anyway, i might say i want icecream: maybe i eat 2, 3 or even more.  I ate 
one summer one icecream cone with 6 balls (the shop offered cones with
even 20 balls).  Said that, I will not eat one cone with 100 icecream balls;
i would prefer to be asked for confirmation before pay it.

`ibuffer-do-view-1' is another example: introduces a hardcoded `3'.
Why `3'?  Isn't it better allow users to define what is in their opinion 
a large number of frames?
It's good having an standard check.  Otherwise we could have one 
Emacs library FOO asking you if nframes > N1 is Ok, and another Emacs 
library BAR asking the same when nframes > N2.

I saw more use cases in 3rd party code where this could be useful.
It might be more cases in Emacs source.