[Scons-dev] Announcement: Core changes for v2.4 ahead, Switching the Node class to using slots...

[Bill Deegan]

Can we use property decorators to resolve this for standard Node properties?

-Bill

On Mon, Mar 2, 2015 at 8:40 AM, Kenny, Jason L <jason.l.kenny at intel.com>
wrote:

> Hi dirk,
>
> I need to give this a run. As I am one of the people that would be in a
> dangerous area :-)
>
> My first thought however would be this:
>
> 1) did we add a __dict__ to the __slots__ ? if not can we, this would
> probally fix 99% of the issues I would have in Parts
> 2)  stuff like t.abspath -> t.get_abspath(), can the t.abspath be a
> property that calls t.get_abspath()?
>
> This seems like this would deal with most of the concerns people might
> have. I understand that there might be good reason not to do this. I
> haven't looked in detail yet myself.
>
> Just some thoughts.
>
> Jason
>
>
> -----Original Message-----
> From: Scons-dev [mailto:scons-dev-bounces at scons.org] On Behalf Of Dirk
> Bächle
> Sent: Saturday, February 28, 2015 6:03 AM
> To: SCons users mailing list
> Cc: SCons developer list
> Subject: [Scons-dev] Announcement: Core changes for v2.4 ahead, Switching
> the Node class to using slots...
>
> Hello there,
>
> as has been pre-announced at
>
>    https://pairlist4.pair.net/pipermail/scons-users/2014-July/002734.html
>
> and
>
>
> https://pairlist2.pair.net/pipermail/scons-dev/2014-December/002107.html
>
> we're still planning to switch the Node class to using "slots" in the core
> sources, mainly for reducing the overall memory consumption by up to 35% in
> large build projects.
>
> We have now pushed a new branch named "switch_to_slots" to the main SCons
> repo, and ran it against our test suite in Buildbot (
> http://buildbot.scons.org/waterfall ). So far, the implementation looks
> stable and for the normal user there shouldn't be any danger of
> scripts/builds breaking after an update to the new release 2.4 (coming
> probably in a month or so).
>
> However, if you write and maintain your own extensions, where you
> regularly reach into the bowels of SCons to extract internal data or to
> override methods (monkey-patching), there is a chance that you'll get
> bitten by the changes as described in the appendix below.
>
> We invite any interested user/developer to try out the current "slots"
> branch, by cloning
>
>    hg clone http://bitbucket.org/scons/scons -r switch_to_slots
>
> to a local folder (not your standard SCons repo!), and starting it via the
> "bootstrap.py" script:
>
>    python ~/try_out_folder/scons/bootstrap.py
>
> Please report back any errors or inconveniences that you find, such that
> we can work on a solution together.
> If you have further questions, better ask them now. We won't look back
> after merging this. ;)
>
>
> Best regards,
>
> Dirk
>
>
> Appendix: Short list of changes to the Node* classes
> ====================================================
>
> - Introduction of decorators for memoizer debugging/counting (we can't use
> metaclasses anymore).
> - Adding interface for accessing node attributes that may get initialized
> lazily:
>       t.abspath -> t.get_abspath()
>       t.labspath -> t.get_labspath()
>       t.tpath -> t.get_tpath()
>       t.path_elements -> t.get_path_elements()
>       t.path -> t.get_internal_path()
>
> - Methods like t.exists(), t.rexists() and t.get_contents() can't be
> re-assigned directly anymore. They'll be realized via function maps
> internally ( {int : func} ).
>
> - NodeInfo and BuildInfo will also get switched to __slots__, and get a
> new internal version number (1.0 -> 2.0). This means that after the switch
> *all* targets are regarded to be out-of-date on the first build.
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