Question: Why do PluginError have a cause argument to the constructor ?

[Carreau]

It seem to like this is trying to do the same as

except ... as e:
     raise PluginError(...) from e

The "from" seem to set the __cause__ the same way the argument does.

It looks like @tlambert03 wrote the code, maybe he knows ?

[tlambert03]

yes, it's doing the same thing. Recall though that one of the main designs of plugin errors was to not raise them, so adding __cause__ is the same as raising from, but without raising. If you'd prefer to raise/catch rather than do it like this, as you did over in the napari PRs, that's fine... same ultimate goal.

(you could do the same thing with tracebacks over there too... but it doesn't matter too much to me. whatever gets the job done)

[Carreau]

Main problem is that if not raising PluginErrors, then the ExecInfo will not have a __traceback__ which will crash the IPython traceback formatter in IPython 8.0+. So I'm fine with the PluginError(cause=e), but I'm a bit worried about the pattern of creating plugin errors that are exception w/o raising them

[tlambert03]

Yeah, I saw that. Like I said, I suspect you could also add a __traceback__ just as I added __cause__ ... but it really doesn't matter to me. whatever you want to do works for me.