[PATCH] evolution: make troubles appear in default log (issue4686)

Matt Mackall mpm at selenic.com
Fri Sep 9 12:31:56 EDT 2016


On Wed, 2016-09-07 at 15:23 -0400, Augie Fackler wrote:
> On Fri, Sep 02, 2016 at 10:26:22AM -0500, Kevin Bullock wrote:
> > 
> > > 
> > > On Sep 2, 2016, at 04:38, liscju <piotr.listkiewicz at gmail.com> wrote:
> > > 
> > > # HG changeset patch
> > > # User liscju <piotr.listkiewicz at gmail.com>
> > > # Date 1472809041 -7200
> > > #      Fri Sep 02 11:37:21 2016 +0200
> > > # Node ID 463b164126a0db3f7147787ace34f74deeccc03f
> > > # Parent  f148bfa40489269be2e48046734f81065129847a
> > > evolution: make troubles appear in default log (issue4686)
> > > 
> > > This patch is request for comment, it does not update failing
> > > test due to new information about troubles, it adds one test
> > > to show how troubles looks like in default log.
> > I think having a way to show troubled changesets as such in the log is a
> > good idea, but the best we're able to do here is to add a new built-in
> > template (cf. `hg log -T phases`). The default log output is very strongly a
> > part of our command-line API, and changing it (even additively!) is a no-no.
> There's caselaw for adding new lines to the -Tdefault output
> (bookmarks come to mind), so I think we can probably do that?

Bookmarks and branches did indeed get output added to default log. But no user
would see that output until they started using those things (one of the reasons
the "default" branch is invisible). So fragile tooling that couldn't handle them
appearing wouldn't break simply from upgrading. 

There are two key points to this pattern:

- no behavior change for repos not using a feature
- output change is introduced WITH the feature

This second is essential to ensure that there's no timeframe where users could
start coding production scripts against the feature and then get broken simply
by upgrading. Note that it IS ok if using a new feature breaks something (that's
unavoidable!) but it's NOT ok if simply upgrading does.

So this boat has already sailed for "troubles", because we've had them for a
while.

-- 
Mathematics is the supreme nostalgia of our time.



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