[PATCH 1 of 2] util: forward __bool__()/__nonzero__() on fileobjectproxy

[Gregory Szorc]

On Sat, Mar 10, 2018 at 10:05 AM, Matt Harbison <mharbison72 at gmail.com>
wrote:

> # HG changeset patch
> # User Matt Harbison <matt_harbison at yahoo.com>
> # Date 1520702528 18000
> #      Sat Mar 10 12:22:08 2018 -0500
> # Node ID e21d0c21f81315d012c4806359bc76aa40c89ad6
> # Parent  963b4223d14fa419df2a82fbe47cd55075707b6a
> util: forward __bool__()/__nonzero__() on fileobjectproxy
>

Good catch.

Queued, thanks.

Proxy objects are hard. FWIW, the most robust implementation I've seen is
http://wrapt.readthedocs.io/en/latest/. If you look at the source code and
bug history of that project, there is some serious magic required to
properly implement a proxy object! If we ever use proxies more seriously in
core, we should consider vendoring wrapt.


>
> In trying to debug the Windows process hang in D2720, I changed the stderr
> pipe
> to the peer to be os.devnull instead.  That caused
> sshpeer._cleanuppipes()[1] to
> explode, complaining NoneType has no __iter__ attribute, even though the
> previous line checked for None.
>
> [1] https://www.mercurial-scm.org/repo/hg/file/b434965f984e/
> mercurial/sshpeer.py#l133
>
> diff --git a/mercurial/util.py b/mercurial/util.py
> --- a/mercurial/util.py
> +++ b/mercurial/util.py
> @@ -551,6 +551,11 @@ class fileobjectproxy(object):
>
>          return getattr(object.__getattribute__(self, r'_orig'), name)
>
> +    def __nonzero__(self):
> +        return bool(object.__getattribute__(self, r'_orig'))
> +
> +    __bool__ = __nonzero__
> +
>      def __delattr__(self, name):
>          return delattr(object.__getattribute__(self, r'_orig'), name)
>
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