[PATCH v2] pager: migrate heavily-used extension into core

[Sean Farley]

Augie Fackler <raf at durin42.com> writes:

>> On Feb 6, 2017, at 18:04, Sean Farley <sean at farley.io> wrote:
>> 
>> Augie Fackler <raf at durin42.com> writes:
>> 
>>> (sending again because this seems to have gotten stuck somewhere...)
>>> (+yuya explicitly for chg thoughts, +smf so someone else can forward to the list if it's stuck again)
>>> 
>>> On Fri, Feb 03, 2017 at 04:16:09PM -0800, Bryan O'Sullivan wrote:
> [...]
>
>>> (This design, btw, was inspired by the way git handles paging, where
>>> it's largely up to the command to decide if it wants to invoke the
>>> pager.)
>> 
>> If I'm understanding you correctly, this will get rid of the
>> pager.attend variable? If that's true, then I fully support that.
>
> Mostly. pager.attend will probably live on as a config knob for users to force paging of commands that don't request it. I can't see it working without that? Though it'd be the alternative form, that looks like

You mean for third-party commands? My conclusion from your previous
email was that all the internal commands would eventually be patched to
use ui.pager, right?

> [pager]
> attend-foo = yes

Is there anything preventing this form?

>>> As a sketch of where this is headed, API-wise:
>>> 
>>> class ui:
>>> def pager(self, command, category):
>>>   ""Starts the pager, if desired by the user.
>>> 
>>>   `command` specifies the current command the user is running,
>>>   something like `log` or `shelve`. It should be the whole original
>>>   command name, not the partial name or alias name.
>>> 
>>>   `category` specifies a broad category this pager invocation fits
>>>   into. Examples include `diff`, `log`, `status`, `help`. This
>>>   allows users to disable paging of entire types of commands easily.
>>>   """
>>>   # pager starts, self.pageractive=true, etc
>>> 
>>> @command
>>> def shelve(ui, ...):
>>> if action == 'list':
>>>   ui.pager('shelve', 'diff' if --patch else 'log')
>>> ...
>>> 
>>> @command
>>> def summary(ui, ...):
>>> ui.pager('summary', 'status')
>>> ...
>> 
>> Would this get rid of the need to set pager.pager=less? I think last
>> time the pager was brought up (I believe the Munich sprint), there was a
>> consensus on not relying on the existence of less / more / windows
>> weirdness.
>
> I don't know about Windows, but I think we should follow git's lead and default to using *a* pager. On debian, that means sensible-pager, on most other unices that means less, on some unfortunate platforms it means more. In-tree, we should probably default to more, with a recommendation that packagers specify a more reasonable default in the system-wide hgrc.
>
> (I've had a PAGER environment variable for longer than I've had my dotfiles source control, but I have no idea how common this is. For some highly unscientific data, I've posted a poll on twitter: https://twitter.com/durin42/status/828742645145075712 - maybe we'll learn something.)

Hmmm, I seem to recall talk about vendoring a python pager? Didn't
Anatoly write one?