People often want to know what they are working on *now*. As part of
this, they also commonly want to know how that work is related to other
changesets in the repo so they can perform common actions like rebase,
histedit, and merge.
`hg show work` made headway into this space. However, it is geared
towards a complete repo view as opposed to just the current line of
work. If you have a lot of in-flight work or the repo has many heads,
the output can be overwhelming. The closest thing Mercurial has to
"show me the current thing I'm working on" that doesn't require custom
revsets is `hg qseries`. And this requires MQ, which completely changes
workflows and repository behavior and has horrible performance on large
repos. But as sub-optimal as MQ is, it does some things right, such as
expose a model of the repo that is easy for people to reason about.
This simplicity is why I think a lot of people prefer to use MQ, despite
its shortcomings.
One common development workflow is to author a series of linear
changesets, using bookmarks, branches, anonymous heads, or even topics
(3rd party extension). I'll call this a "stack." You periodically
rewrite history in place (using `hg histedit`) and reparent the stack
against newer changesets (using `hg rebase`). This workflow can be
difficult because there is no obvious way to quickly see the current
"stack" nor its relation to other changesets. Figuring out arguments to
`hg rebase` can be difficult and may require highlighting and pasting
multiple changeset nodes to construct a command.
The goal of this commit is to make stack based workflows simpler
by exposing a view of the current stack and its relationship to
other releant changesets, notably the parent of the base changeset
in the stack and newer heads that the stack could be rebased or merged
into.
Introduced is the `hg show stack` view. Essentially, it finds all
mutable changesets from the working directory revision in both
directions, stopping at a merge or branch point. This limits the
revisions to a DAG linear range.
The stack is rendered as a concise list of changesets. Alongside the
stack is a visualization of the DAG, similar to `hg log -G`.
Newer public heads from the branch point of the stack are rendered
above the stack. The presence of these heads helps people understand
the DAG model and the relationship between the stack and changes made
since the branch point of that stack. If the "rebase" command is
available, a `hg rebase` command is printed for each head so a user
can perform a simple copy and paste to perform a rebase.
This view is alpha quality. There are tons of TODOs documented
inline. But I think it is good enough for a first iteration.
This commit addresses a number of deficiencies in `hg show work`'s
output:
* Failure to render tags (it just wasn't implemented)
* Failure to render names associated with non-built-in namespaces
(e.g. remotenames)
* Color names were hardcoded instead of coming from the canonical
source in the namespace
This change has the intended effect of rendering tags and extra
namespaces. It solves an immediate need at Mozilla of having
names from a custom namespace printed, which is blocking us from
switching from a custom `hg wip` revset/template combo to `hg show
work`.
Note that the order of branches and bookmarks changes. This is
because bookmarks are registered before branches in namespaces.py.
We may want to register them last, after tags and branches. Or we
may want to added a weighted field to the namespace to control
display order. Something to think about.
I'm not a big fan of the complexity in the templating layer. There
is a lot of code to basically filter out the special case of
branch=='default' and tag=='tip'. Ideally, we would iterate over
a data structure that had irrelevant/unwanted names pre-filtered.
However, I wasn't sure how to best implement this. We probably
want {namespaces} to emit everything (its current behavior). I
was toying with the following:
* {namespacesnondefaults} variation that filtered values
* A filter function that operated on {namespaces} (I wasn't sure
how to implement this since the filtering layer would see a
"hybrid" instance as opposed to something that was definitely
an iterable of namespaces.)
* A namespaces(...) function where you could specify which values
to return. I like this the most. But it really wants named
arguments to control filtering and we only support named arguments
on revsets, not templates.
I figure perfect is the enemy of good and we can refine templating
support for namespaces in the future. At least now we have a
concrete example of a use case.
Previously, we constructed a formatter from a specific template
topic. Then from show() we reached into the internals of the
formatter to resolve a template string to be used to construct
a changeset templater.
A downside to this approach was it limited us to having the
entire template defined in a single entry in the map file. You
couldn't reference other entries in the map file and this would
lead to long templates and redundancy in the map file.
This commit teaches @showview how to instantiate a changeset
templater so we can construct a templater with full access to
the map file. To prove it works, we've split "showwork" into
components.
`hg show work` is much more usable if output is colored. This patch
implements coloring via label() in a very hacky way.
In a default Mercurial install, you'll see yellow node labels for all
phases. Branches and bookmarks use the same formatting as the commit
message. So this change doesn't help much in a default install. But if
you have a custom colors defined for these things, output is much more
readable.
The implementation obviously needs some work. But for a minor change
on a feature that isn't convered by BC, this seems like a clear win
for the feature in 4.2.
Durham and I both like this better than "underway." We can add aliases
and bikeshed on the name during the 4.3 cycle, as this whole extension is
highly experimental.
This is the beginning of a wip/smartlog view. It is basically a manually
constructed (read: fast) revset function to collect "relevant"
changesets combined with a custom template and a graph displayer.
It obviously needs a lot of work.
I'd like to get *something* usable in 4.2 so `hg show` has some value
to end-users.
Let the bikeshedding begin.
Currently, Mercurial has a number of commands to show information. And,
there are features coming down the pipe that will introduce more
commands for showing information.
Currently, when introducing a new class of data or a view that we
wish to expose to the user, the strategy is to introduce a new command
or overload an existing command, sometimes both. For example, there is
a desire to formalize the wip/smartlog/underway/mine functionality that
many have devised. There is also a desire to introduce a "topics"
concept. Others would like views of "the current stack." In the
current model, we'd need a new command for wip/smartlog/etc (that
behaves a lot like a pre-defined alias of `hg log`). For topics,
we'd likely overload `hg topic[s]` to both display and manipulate
topics.
Adding new commands for every pre-defined query doesn't scale well
and pollutes `hg help`. Overloading commands to perform read-only and
write operations is arguably an UX anti-pattern: while having all
functionality for a given concept in one command is nice, having a
single command doing multiple discrete operations is not. Furthermore,
a user may be surprised that a command they thought was read-only
actually changes something.
We discussed this at the Mercurial 4.0 Sprint in Paris and decided that
having a single command where we could hang pre-defined views of
various data would be a good idea. Having such a command would:
* Help prevent an explosion of new query-related commands
* Create a clear separation between read and write operations
(mitigates footguns)
* Avoids overloading the meaning of commands that manipulate data
(bookmark, tag, branch, etc) (while we can't take away the
existing behavior for BC reasons, we now won't introduce this
behavior on new commands)
* Allows users to discover informational views more easily by
aggregating them in a single location
* Lowers the barrier to creating the new views (since the barrier
to creating a top-level command is relatively high)
So, this commit introduces the `hg show` command via the "show"
extension. This command accepts a positional argument of the
"view" to show. New views can be registered with a decorator. To
prove it works, we implement the "bookmarks" view, which shows a
table of bookmarks and their associated nodes.
We introduce a new style to hold everything used by `hg show`.
For our initial bookmarks view, the output varies from `hg bookmarks`:
* Padding is performed in the template itself as opposed to Python
* Revision integers are not shown
* shortest() is used to display a 5 character node by default (as
opposed to static 12 characters)
I chose to implement the "bookmarks" view first because it is simple
and shouldn't invite too much bikeshedding that detracts from the
evaluation of `hg show` itself. But there is an important point
to consider: we now have 2 ways to show a list of bookmarks. I'm not
a fan of introducing multiple ways to do very similar things. So it
might be worth discussing how we wish to tackle this issue for
bookmarks, tags, branches, MQ series, etc.
I also made the choice of explicitly declaring the default show
template not part of the standard BC guarantees. History has shown
that we make mistakes and poor choices with output formatting but
can't fix these mistakes later because random tools are parsing
output and we don't want to break these tools. Optimizing for human
consumption is one of my goals for `hg show`. So, by not covering
the formatting as part of BC, the barrier to future change is much
lower and humans benefit.
There are some improvements that can be made to formatting. For
example, we don't yet use label() in the templates. We obviously
want this for color. But I'm not sure if we should reuse the existing
log.* labels or invent new ones. I figure we can punt that to a
follow-up.
At the aforementioned Sprint, we discussed and discarded various
alternatives to `hg show`.
We considered making `hg log <view>` perform this behavior. The main
reason we can't do this is because a positional argument to `hg log`
can be a file path and if there is a conflict between a path name and
a view name, behavior is ambiguous. We could have introduced
`hg log --view` or similar, but we felt that required too much typing
(we don't want to require a command flag to show a view) and wasn't
very discoverable. Furthermore, `hg log` is optimized for showing
changelog data and there are things that `hg display` could display
that aren't changelog centric.
There were concerns about using "show" as the command name.
Some users already have a "show" alias that is similar to `hg export`.
There were also concerns that Git users adapted to `git show` would
be confused by `hg show`'s different behavior. The main difference
here is `git show` prints an `hg export` like view of the current
commit by default and `hg show` requires an argument. `git show`
can also display any Git object. `git show` does not support
displaying more complex views: just single objects. If we
implemented `hg show <hash>` or `hg show <identifier>`, `hg show`
would be a superset of `git show`. Although, I'm hesitant to do that
at this time because I view `hg show` as a higher-level querying
command and there are namespace collisions between valid identifiers
and registered views.
There is also a prefix collision with `hg showconfig`, which is an
alias of `hg config`.
We also considered `hg view`, but that is already used by the "hgk"
extension.
`hg display` was also proposed at one point. It has a prefix collision
with `hg diff`. General consensus was "show" or "view" are the best
verbs. And since "view" was taken, "show" was chosen.
There are a number of inline TODOs in this patch. Some of these
represent decisions yet to be made. Others represent features
requiring non-trivial complexity. Rather than bloat the patch or
invite additional bikeshedding, I figured I'd document future
enhancements via TODO so we can get a minimal implmentation landed.
Something is better than nothing.
