[Python-ideas] Idea: Allow multiple levels of tracers

[Ram Rachum]

Oh wow, I didn't even consider that. I think you're right, I'll do more
thinking about this. Thanks Anders!

On Thu, Apr 25, 2019 at 6:10 PM Anders Hovmöller <boxed at killingar.net>
wrote:

> Can't this be implemented today by a simple monkey patch of sys.settrace?
>
> On 25 Apr 2019, at 16:51, Ram Rachum <ram at rachum.com> wrote:
>
> Hi,
>
> Here's something I want in Python: Multiple levels of tracers working on
> top of each other, instead of just one.
>
> I'm talking about the tracer that one can set by calling sys.settrace.
>
> I've recently released PySnooper: https://github.com/cool-RR/PySnooper/
>
> One of the difficulties I have, is that I can't debug or run the
> `coverage` tool on the core of this module. That's because the core is a
> trace function, and debuggers and coverage tools work by setting a trace
> function. When PySnooper sets its trace function using `sys.settrace`, the
> code that runs in that trace function runs without getting traced by the
> coverage tracer.
>
> This means that people who develop debuggers and coverage tools can't use
> a debugger or a coverage tool on the core of their tool. It's quite an
> annoying problem.
>
> My proposed solution: Multiple levels of tracing, instead of just one.
> When you install a tracer, you're not replacing the existing one, you're
> appending a tracer to the existing list of tracers.
>
> If this was implemented, then when PySnooper would install its tracer, the
> coverage tracer would still be active and running, for every line of code
> including the ones in PySnooper's tracer.
>
> Obviously, we'll need to figure out the API and any other kind of problems
> with this proposal.
>
> What do you think?
>
>
> Thanks,
> Ram.
>
>
> _______________________________________________
> Python-ideas mailing list
> Python-ideas at python.org
> https://mail.python.org/mailman/listinfo/python-ideas
> Code of Conduct: http://python.org/psf/codeofconduct/
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-ideas/attachments/20190425/5902e53d/attachment.html>