[PATCH 5 of 5] ui: avoid needless casting to a str

[Gregory Szorc]

On Wed, Nov 25, 2015 at 4:55 AM, Yuya Nishihara <yuya at tcha.org> wrote:

> On Tue, 24 Nov 2015 13:11:42 -0800, Gregory Szorc wrote:
> > # HG changeset patch
> > # User Gregory Szorc <gregory.szorc at gmail.com>
> > # Date 1448232295 28800
> > #      Sun Nov 22 14:44:55 2015 -0800
> > # Node ID 5d5af88a927bbffa921f76f6600e0e67475df369
> > # Parent  e3c27c5cece623b52b053f84698446855e908396
> > ui: avoid needless casting to a str
> >
> > In many cases, we don't need to cast to a str because the object will
> > be cast when it is eventually written.
> >
> > As part of testing this, I added some code to raise exceptions when a
> > non-str was passed in and wasn't able to trigger it. i.e. we're already
> > passing str into this function everywhere, so the casting isn't
> > necessary.
> >
> > diff --git a/hgext/color.py b/hgext/color.py
> > --- a/hgext/color.py
> > +++ b/hgext/color.py
> > @@ -433,18 +433,17 @@ class colorui(uimod.ui):
> >
> >          label = opts.get('label', '')
> >          if self._buffers:
> >              if self._bufferapplylabels:
> > -                self._buffers[-1].extend(self.label(str(a), label)
> > -                                         for a in args)
> > +                self._buffers[-1].extend(self.label(a, label) for a in
> args)
> >              else:
> > -                self._buffers[-1].extend(str(a) for a in args)
> > +                self._buffers[-1].extend(args)
> >          elif self._colormode == 'win32':
> >              for a in args:
> >                  win32print(a, super(colorui, self).write, **opts)
> >          else:
> >              return super(colorui, self).write(
> > -                *[self.label(str(a), label) for a in args], **opts)
> > +                *[self.label(a, label) for a in args], **opts)
> >
> >      def write_err(self, *args, **opts):
> >          if self._colormode is None:
> >              return super(colorui, self).write_err(*args, **opts)
> > @@ -456,9 +455,9 @@ class colorui(uimod.ui):
> >              for a in args:
> >                  win32print(a, super(colorui, self).write_err, **opts)
> >          else:
> >              return super(colorui, self).write_err(
> > -                *[self.label(str(a), label) for a in args], **opts)
> > +                *[self.label(a, label) for a in args], **opts)
> >
> >      def showlabel(self, msg, label):
> >          if label and msg:
> >              if msg[-1] == '\n':
> > diff --git a/mercurial/ui.py b/mercurial/ui.py
> > --- a/mercurial/ui.py
> > +++ b/mercurial/ui.py
> > @@ -622,12 +622,12 @@ class ui(object):
> >          a label of "status.modified" for modified files.
> >          '''
> >          self._progclear()
> >          if self._buffers:
> > -            self._buffers[-1].extend([str(a) for a in args])
> > +            self._buffers[-1].extend(a for a in args)
>
> This is somewhat related. Can we call self.label(a, label) here so that
> colorui won't have to care about _bufferapplylabels?
>
> Or we can't because it would make things slow?
>

When I spent a few hours trying to figure out how to make `hg log` as fast
as possible, color definitely added noticeable overhead over plain. Even
some % string formatting shows up in statprof for `hg log`!

I didn't measure this specifically, but I suspect with the high frequency
write() is called that the function call overhead would have an impact.
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