Re: Patch: debug-instrumented predicate

[Stefan Monnier <monnier@iro.umontreal.ca>]

Arthur Miller [2021-10-04 23:58:26] wrote:
> Stefan Monnier <monnier@iro.umontreal.ca> writes:
>>> Concrete use-case would be to offer a user some kind of gui to instrument or remove
>>> instrumentation for debug/edebug/profile/trace.
>>
>> W.r.t *removal* of debug/profile/trace, this could be done by offering
>> a generic removal GUI for advice.
>
> Njah, advice already has add/remove which can be connected to a gui button or
> what not. However any generic interface always need a specialisation for a case
> at hand anyway, at least a different label on a button. But we are drifting
> away.

I don't think it's drifting: I'm suggesting that we try to add support
for it in a way that supports them all at the same time.

> I ask/suggest for an API to discover if instrumentation is installed or not.

And I'm suggesting that make `advice-member-p` should be the way to do that.
Currently this requires reliance on some internal knowledge of the
advice's name, but we could fix it by making this name public&stable.

> The only one that truly is missing a mean to test for on/off state is edebug.

Indeed.  I haven't looked at whether it could be made to use
`advice-add` so that `advice-member-p` could be used as well.
There's a good chance that it's not really an option (I mean
technically, I'm pretty sure it could be done, but I suspect it will
come with enough downsides that it's not worth it).

Until it can be made to use `advice-member-p` we should indeed export
a public way to test whether a function is instrumented by Edebug.

> I don't know which one is more efficient, but I don't like neither of those two,
> I don't think any of suggested solutions is efficient. Also they both rely on
> internal state that can change whenever.

As long as these functions are defined in `edebug.el` it's OK if they
rely on internal state.

> When a function is instrumented for edebug, edebug adds some properties into
> symbols property list. However when instrumentation is removed, edebug leaves
> those properties to scrap behind; that inclusive the position in buffer where it
> was active. IMO it is a bug; it shouldn't leave scrap behind. It would also be
> trivial to check if a funciton is instrumented or not, if those properties were
> removed when instrumentation is removed.
>
> Unless I misunderstand the purpose why properties are left behind after
> instrumentation is removed :).

I suspect they're not left behind for any good reason, and
the best way to find out is to remove them and see if someone screams.


        Stefan