Have pretty_print.py find histograms.xml.

Have pretty_print.py find histograms.xml.

Whenever I need to pretty print histograms.xml, I always forget that
it wants to be run from the directory containing histograms.xml. This
CL fixes that, by having the tool look for the directory from which it's
running.

R=isherman@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=243267

[gavinp, 2013-12-26 21:02:56]

asvitkine: PTAL.

[Ilya Sherman, 2013-12-26 21:41:56]

Thanks for the cleanup!

Please use path_utils.ScriptDir() rather than re-implementing that functionality
yourself.  Also, please either adopt the pattern used in extract_actions.py [1],
or update that script to also use chdir.  (I personally slightly prefer the
approach taken in extract_actions.py, as it's a little harder to miss what's
happening for anyone reading the code for the first time -- but I don't feel too
strongly about it.  I'd just like us to be consistent.)

https://code.google.com/p/chromium/codesearch#chromium/src/tools/metrics/acti...

[gavinp, 2013-12-27 14:05:24]

Ilya,

How do you like this?

I am a bit amused that in order to import path_utils.ScriptDir() I had to...
implement path_utils.ScriptDir() in a one liner.

[Ilya Sherman, 2013-12-27 21:48:05]

Thanks, Gavin!  LGTM % nit.

Also, happy birthday :)  [Thanks, slightly creepy internal tools...]

https://codereview.chromium.org/121403002/diff/40001/tools/metrics/histograms...
File tools/metrics/histograms/pretty_print.py (right):

https://codereview.chromium.org/121403002/diff/40001/tools/metrics/histograms...
tools/metrics/histograms/pretty_print.py:26: sys.path.insert(1,
os.path.join(sys.path[0], '..', '..', 'python'))
Hmm, I hadn't noticed that this was needed to support path_utils... that's
pretty silly.  Still, though, I think the resulting code is cleaner this way
than as it was before, and also matches extract_actions.py, which is nice. 
Thanks!

https://codereview.chromium.org/121403002/diff/40001/tools/metrics/histograms...
tools/metrics/histograms/pretty_print.py:356: os.path.join(script_dir,
'histograms.before.pretty-print.xml'))
nit: Please declare named constants for the file names, especially so that you
don't need to repeat "os.path.join(script_dir, 'histograms.xml')" throughout.

[gavinp, 2014-01-06 17:36:06]

Thanks for the birthday wishes. I've updated this per review, and I'll CQ it
later today.

https://codereview.chromium.org/121403002/diff/40001/tools/metrics/histograms...
File tools/metrics/histograms/pretty_print.py (right):

https://codereview.chromium.org/121403002/diff/40001/tools/metrics/histograms...
tools/metrics/histograms/pretty_print.py:356: os.path.join(script_dir,
'histograms.before.pretty-print.xml'))
On 2013/12/27 21:48:05, Ilya Sherman (Away thru Jan 6) wrote:
> nit: Please declare named constants for the file names, especially so that you
> don't need to repeat "os.path.join(script_dir, 'histograms.xml')" throughout.

Done. I did this with automatic variables though in the function scope (like
script_dir), to maintain locality of reference, which I think enhances
readability. Let me know if you want me to change these.

[Ilya Sherman, 2014-01-06 23:22:36]

https://codereview.chromium.org/121403002/diff/40001/tools/metrics/histograms...
File tools/metrics/histograms/pretty_print.py (right):

https://codereview.chromium.org/121403002/diff/40001/tools/metrics/histograms...
tools/metrics/histograms/pretty_print.py:356: os.path.join(script_dir,
'histograms.before.pretty-print.xml'))
On 2014/01/06 17:36:07, gavinp wrote:
> On 2013/12/27 21:48:05, Ilya Sherman (Away thru Jan 6) wrote:
> > nit: Please declare named constants for the file names, especially so that
you
> > don't need to repeat "os.path.join(script_dir, 'histograms.xml')"
throughout.
> 
> Done. I did this with automatic variables though in the function scope (like
> script_dir), to maintain locality of reference, which I think enhances
> readability. Let me know if you want me to change these.

This is fine, thanks.

[commit-bot: I haz the power, 2014-01-06 23:27:16]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gavinp@chromium.org/121403002/160001

[commit-bot: I haz the power, 2014-01-07 11:55:07]

Change committed as 243267