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bug#65344: 28.2; Unable to Edebug cl-flet form which uses argument destr
From: |
Stefan Monnier |
Subject: |
bug#65344: 28.2; Unable to Edebug cl-flet form which uses argument destructuring |
Date: |
Sat, 02 Sep 2023 13:04:57 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) |
>>> The problem seems to be the attempt to first match the spec
>>>
>>> (&define [&name symbolp "@cl-flet@"]
>>> [&name [] gensym] ;Make it unique!
>>> def-form)])
>>
>> I think this is not right:
>>
>> - `def-form` is for use by forms which will be run "later", meaning that
>> we can start executing those instrumented form while running
>> non-instrumented code (like the inside of a lambda), so it should not
>> be needed here: we should use just `form`.
>
> I don't think I get that yet. Let's say we have
>
> (cl-flet ((f (lambda () (list 1 2))))
> (f))
>
> In this case, the code for F will be run in the body of the
> flet. Doesn't that qualify as being run later, as you describe above,
> ignoring the "non-instrumented" part, maybe?
No, in the above case the `def-form` is
(lambda () (list 1 2))
which will be "run" right when we enter the `cl-flet` ("run" is an
exaggeration here since this lambda is a constant so it'll just
self-evaluate) and not when `f` is called.
> (Just from the perspective of behaviour, C-u C-M-x on the flet above does
> seem to do what I'd expect: the call to F let's me step into the
> body of the lambda.)
Yes, it is harmless for debugging purposes (at most it makes things ever
so slightly less efficient by having to process a few more
`edebug-enter`s than needed).
>> - The &define+&name isn't quite right here. In `(cl-flet ((F EXP)) ...)`
>> it tells Edebug that EXP should be given the name F whereas the `cl-flet`
>> actually gives the name F to the value returned by EXP.
>> [ In terms of code coverage, F will then always be considered as
>> covered just because we have to execute EXP in order to discover the
>> function to bind to F. ]
>>
>> I think that's why the old code had just `(symbolp form)`:
>> it's difficult with `(cl-flet ((F EXP)) ...)` to give a name to the
>> right thing :-(
>
> I'm afraid I know nothing about coverage, so I can't say something
> halfways intelligent to that.
The whole `&name` business is of no use for the single-step debugger,
it's only useful for other uses of the instrumentation such as
code-coverage.
Stefan
- bug#65344: 28.2; Unable to Edebug cl-flet form which uses argument destructuring, Stefan Monnier, 2023/09/01
- bug#65344: 28.2; Unable to Edebug cl-flet form which uses argument destructuring, Gerd Möllmann, 2023/09/02
- bug#65344: 28.2; Unable to Edebug cl-flet form which uses argument destructuring,
Stefan Monnier <=
- bug#65344: 28.2; Unable to Edebug cl-flet form which uses argument destructuring, Stefan Monnier, 2023/09/02
- bug#65344: 28.2; Unable to Edebug cl-flet form which uses argument destructuring, Gerd Möllmann, 2023/09/03
- bug#65344: 28.2; Unable to Edebug cl-flet form which uses argument destructuring, Stefan Monnier, 2023/09/03
- bug#65344: 28.2; Unable to Edebug cl-flet form which uses argument destructuring, Gerd Möllmann, 2023/09/03
- bug#65344: 28.2; Unable to Edebug cl-flet form which uses argument destructuring, Stefan Monnier, 2023/09/04