[PATCH 1 of 3] demandimport: define an importnow context manager

[Augie Fackler]

On Tue, May 26, 2015 at 01:45:12PM -0700, Pierre-Yves David wrote:
>
>
> On 05/26/2015 01:35 PM, Jordi Gutiérrez Hermoso wrote:
> ># HG changeset patch
> ># User Jordi Gutiérrez Hermoso <jordigh at octave.org>
> ># Date 1432671771 14400
> >#      Tue May 26 16:22:51 2015 -0400
> ># Node ID ac165f67eab4ab8157f73ab229e80883d49fabe0
> ># Parent  6ac860f700b5cfeda232d5305963047696b869ca
> >demandimport: define an importnow context manager
> >
> >This can be useful for use in "with" blocks for temporarily disabling
> >demandimport.
> >
> >diff --git a/mercurial/demandimport.py b/mercurial/demandimport.py
> >--- a/mercurial/demandimport.py
> >+++ b/mercurial/demandimport.py
> >@@ -25,6 +25,8 @@ These imports will not be delayed:
> >  '''
> >
> >  import __builtin__, os, sys
> >+from contextlib import contextmanager
> >+
> >  _origimport = __import__
> >
> >  nothing = object()
> >@@ -179,3 +181,14 @@ def enable():
> >  def disable():
> >      "disable global demand-loading of modules"
> >      __builtin__.__import__ = _origimport
> >+
> >+ at contextmanager
> >+def importnow():
>
> what about: nodemandimport?

Since we're painting this shed, what about immediate? So it'd be:

with demandimport.immediate():
  ...

(I really don't feel strongly about the name, Jordi, feel encouraged
to pick what seems sensible.)

>
> >+    demandenabled = isenabled()
> >+    if demandenabled:
> >+        disable()
> >+
> >+    yield
> >+
> >+    if demandenabled:
> >+        enable()
>
> You want:
>
>    try:
>        yield
>    finally:
>        if demandenabled:
>             enable()
>
>
> otherwise you will fail to restore in case of error.

+1. I'll await a resend once you two work out the name and will look
to see this change in the next round. Thanks!

>
> --
> Pierre-Yves David
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