On Fri, Feb 10, 2017 at 01:07:49PM -0800, Jun Wu wrote:
> Side-effects are basically everything related to writes, like mutating
> (wrapping) internal Python objects, etc. They are done by Python code
> provided by an extension out of core's control. Usually that means
> reposetup, uisetup, etc.
Usually, but not always - I've seen many extensions that call
wrapfunction or similar outside of {repo,ui}setup.
>
> Reading things is fine - loading configs, changelog.i, obsstore, etc. as
> long as no malicious extension changes the loading logic. Currently for chg
> to work correctly, this assumption must be true.
>
> The difference of the above two is whether we can revert the effects. For
> objects loaded by reading certain things, once we discard the object, the
> effect is considered reverted. But for things like x.__class__ = y;
> extensions.wrapfoo(...), etc., they are basically impossible to revert
> cleanly (confidently). So we avoid them at all costs.
I'm having trouble wrapping my head around this series in a useful way
- should we defer it to the sprint, or do you want to try and explain
the arc of this a little more in a v2 with more details in the first
commit message as to what you mean by side effects and what the
expected boundary between these components is?
(I'm specifically a little perplexed by the inheritance relationship
to avoid side effects, I just can't quite get my head around it.)
>
>
> Excerpts from Kevin Bullock's message of 2017-02-10 14:53:22 -0600:
> > > On Feb 9, 2017, at 19:46, Jun Wu <qu...@fb.com> wrote:
> > >
> > > # HG changeset patch
> > > # User Jun Wu <qu...@fb.com>
> > > # Date 1486675034 28800
> > > # Thu Feb 09 13:17:14 2017 -0800
> > > # Node ID 5e47a19fae82f4659f1e7df37f8f26dd56c4f246
> > > # Parent 2c1834e1e6b5f734c27199d47de9b2252b8f4913
> > > # Available At https://bitbucket.org/quark-zju/hg-draft
> > > # hg pull https://bitbucket.org/quark-zju/hg-draft -r
> > > 5e47a19fae82
> > > localrepo: move ui loading to baselocalrepository
> >
> > I can't quite say exactly why, but it surprised me that you're loading the
> > repo's hgrc in the "side-effect-free" base class. We're not loading
> > extensions, but the hgrc can maybe do other things that could be
> > considered "side effects".
> >
> > It's a vague request I know, but could you tell us a little bit more about
> > what specific "side effects" get in the way of your chg work, and maybe
> > why other things in the config won't cause problems?
> >
> > pacem in terris / мир / शान्ति / سَلاَم / 平和 Kevin R.
> > Bullock
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