Get plugin corresponding to return values when calling hook

[youngmit]

Perhaps this is already possible, and I am just missing something, but is it possible to determine which plugin returned each value from a hook call? This would be valuable information for providing error messages and the like in situations where one and only one plugin should return a value under certain circumstances. Being able to report which plugins returned which values would be nice. Perhaps something like an alternative hook calling mechanism, which would return a dictionary (keyed on plugin namespace), rather than a list?

[simonw]

I'm interested in this too, also for debugging purposes. I'd like to display an HTML comment on a page that shows which plugin was responsible for returning a specific piece of information.

[fschulze]

I'm also in need to trace which plugin returned the result, so I wrote this:

def traced_pluggy_call(hook, **caller_kwargs):
    firstresult = hook.spec.opts.get("firstresult", False) if hook.spec else False
    results = []
    plugin_names = []
    hookimpls = hook._hookimpls if hasattr(hook, '_hookimpls') else hook.get_hookimpls()
    for hook_impl in reversed(hookimpls):
        args = [caller_kwargs[argname] for argname in hook_impl.argnames]
        res = hook_impl.function(*args)
        if res is not None:
            results.append(res)
            plugin_names.append(hook_impl.plugin_name)
            if firstresult:
                break
    if firstresult:
        results = results[0] if results else None
    return (results, plugin_names)

Would be great if such functionality could be added somehow.