questions about post_change_branch_tip hook

[John Arbash Meinel]

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Alexander Belchenko wrote:
> I have some question about post_change_branch_tip:
> 
> 1) Documentation on
> http://doc.bazaar.canonical.com/test/en/user-reference/hooks-help.html#post-change-branch-tip
> said this hook triggered for push, pull, commit, uncommit. What about
> update command for bound branches? This hook should be invoked for the
> update too, IIUC? Can you reflects this in the help, please?
> 

It is triggered any time the *branch* tip revision changes, which may
not happen for 'update' (if it only updates the WT, etc). I think adding
an 'etc' is reasonable, as I don't think we catch all of the cases by
just listing commands we think about.

> 2) I'm thinking about how to store previous branch tip for pull/update
> operations so I can implement something like whatsnew command to see the
> log (and/or changes) introduced by the last pull.
> 
> Question: how can I know in the hook which exactly operation updates the
> tip? ChangeBranchTipParams has no context for this. Should I use
> post_pull hook instead? It seems very old, I hope there is no plans to
> deprecate/remove it?

We generally don't propagate information about what command is running
down to the lower layers. It does happen that sometimes Branch.pull() is
called versus Branch.update(), but Branch.update() could be defined in
terms of Branch.pull() (I think they currently re-use a common helper,
but they could easily be layered differently in the future.)

I don't really know what you want for 'missing' that is different from
'bzr missing'. Or at least a variant of that. You may want to define the
use cases.

I believe that 'ChangeBranchTipParams' *does* include the information
about what revision the branch was at before the update, and then what
it will be after the update. You could just save the 'before update'
revision, and use that for 'whatsnew'.

John
=:->
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