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Prints out python variables in an easy to read way, handy for debugging

Project description

A collection of handy functions for printing out variables and debugging code.

print() was too hard to read, pprint wasn’t much better. I was also getting sick of typing: print "var = ", var.

This tries to print out variables with their name, and for good measure, it also prints where the pout function was called from, so you can easily find it and delete it when you’re done.

Methods

pout.v(arg1, [arg2, …]) – easy way to print variables

example

foo = 1
pout.v(foo)

bar = [1, 2, [3, 4], 5]
pout.v(bar)

should print something like:

foo = 1
(/file.py:line)

bar (4) =
[
        0: 1,
        1: 2,
        2:
                [
                        0: 3,
                        1: 4
                ],
        3: 5
]
(/file.py:line)

You can send as many variables as you want into the call

# pass in as many variables as you want
pout.v(foo, bar, che)

# a multi-line call is also fine
pout.v(
    foo,
    bar
)

pout.h() – easy way to print “here” in the code

example

pout.h(1)
# do something else
pout.h(2)

# do even more of something else
pout.h()

Should print something like:

here 1 (/file.py:line)

here 2 (/file.py:line)

here (/file.py:line)

pout.t() – print a backtrace

Prints a nicely formatted backtrace, by default this should compact system python calls (eg, anything in dist-packages) which makes the backtrace easier for me to follow.

example:

pout.t()

should print something like:

15 - C:\Python27\lib\runpy.py:162
14 - C:\Python27\lib\runpy.py:72
13 - C:\Python27\lib\unittest\__main__.py:12
12 - C:\Python27\lib\unittest\main.py:95
11 - C:\Python27\lib\unittest\main.py:229
10 - C:\Python27\lib\unittest\runner.py:151
09 - C:\Python27\lib\unittest\suite.py:65
08 - C:\Python27\lib\unittest\suite.py:103
07 - C:\Python27\lib\unittest\suite.py:65
06 - C:\Python27\lib\unittest\suite.py:103
05 - C:\Python27\lib\unittest\suite.py:65
04 - C:\Python27\lib\unittest\suite.py:103
03 - C:\Python27\lib\unittest\case.py:376
02 - C:\Python27\lib\unittest\case.py:318
01 - C:\Projects\Pout\_pout\src\test_pout.py:50

        pout.t()

pout.p([title]) – quick and dirty profiling

example

p("starting profile")
time.sleep(1)
p() # stop the "starting profile" session


# you can go N levels deep
p("one")
p("two")
time.sleep(0.5)
p() # stop profiling of "two"
time.sleep(0.5)
p() # stop profiling of "one"


# you can also use with
with p("benchmarking"):
    time.sleep(0.5)

should print something like:

starting profile - 1008.2 ms
  start: 1368137723.7 (/file/path:n)
  stop: 1368137724.71(/file/path:n)


one > two - 509.2 ms
  start: 1368137722.69 (/file/path:n)
  stop: 1368137723.2(/file/path:n)


one - 1025.9 ms
  start: 1368137722.68 (/file/path:n)
  stop: 1368137723.7(/file/path:n)

pout.x([exit_code]) – like sys.exit(exit_code)

This just prints out where it was called from, so you can remember where you exited the code while debugging

example:

pout.x()

will print something like this before exiting with an exit code of 1:

exit (/file/path:n)

pout.b([title[, rows[, sep]]]) – prints lots of lines to break up output

This is is handy if you are printing lots of stuff in a loop and you want to break up the output into sections.

example:

pout.b()
pout.b('this is the title')
pout.b('this is the title 2', 5)
pout.b('this is the title 3', 3, '=')

Would result in output like:

********************************************************************************
(/file/path:n)


****************************** this is the title *******************************
(/file/path:n)


********************************************************************************
********************************************************************************
***************************** this is the title 2 ******************************
********************************************************************************
********************************************************************************
(/file/path:n)


================================================================================
============================= this is the title 3 ==============================
===============================================================================
(/file/path:n)

pout.c(str1, [str2, …]) – print info about each char in each str

Kind of like od -c on the command line.

example:

pout.c('this')

will print something like:

Total Characters: 4
t   't' \u0074  LATIN SMALL LETTER T
h   'h' \u0068  LATIN SMALL LETTER H
i   'i' \u0069  LATIN SMALL LETTER I
s   's' \u0073  LATIN SMALL LETTER S
(/file/path:n)

This could fail if Python isn’t compiled with 4 byte unicode support, just something to be aware of, but chances are, if you don’t have 4 byte unicode supported Python, you’re not doing much with 4 byte unicode.

pout.s(arg1, [arg2, …]) – easy way to return pretty versions of variables

Just like pout.v() but will return the value as a string

pout.ss(arg1, [arg2, …]) – easy way to return pretty versions of variables without meta information

Just like pout.vv() but will return the value as a string

pout.l([logger_name, [logger_level]]) – turn logging on just for this context

Turns logging on for the given level (defaults to logging.DEBUG) and prints the logs to stderr. Useful when you just want to check the logs of something without modifying your current logging configuration.

example:

with pout.l():
    logger.debug("This will print to the screen even if logging is off")
logger.debug("this will not print if logging is off")

with pout.l("name"):
    # if "name" logger is used it will print to stderr
# "name" logger goes back to previous configuration

Customizing Pout

object magic method

Any class object can define a __pout__ magic method, similar to Python’s built in __str__ magic method that can return a customized string of the object if you want to. This method can return anything, it will be run through Pout’s internal stringify methods to convert it to a string and print it out.

pout.pout_class

You can create your own class and set this module variable and any pout method will then use your custom class:

class PoutChild(pout.Pout):
    pass

# any pout.* calls will now use your child class, customize as you like
pout.pout_class = PoutChild

Console commands

pout.json

running a command on the command line that outputs a whole a bunch of json? Pout can help:

$ some-command-that-outputs-json | pout.json

pout.char

Runs pout.c but on the output from a command line script:

$ echo "some string with chars to analyze" | pout.char

Install

Use PIP

pip install pout

Generally, the pypi version and the github version shouldn’t be that out of sync, but just in case, you can install from github also:

pip install git+https://github.com/Jaymon/pout#egg=pout

Make Pout easier to use

Add pout to a configuration file for your app

If, like me, you hate having to constantly do import pout at the top of every module you want to use pout in, you can put this snippet of code in your dev environment so you no longer have to import pout:

# handy for dev environment, make pout available to all modules without an import
import __builtin__
try:
  import pout
  __builtin__.pout = pout
except ImportError:
  pass

Read more on what the above snippet does.

Add pout to usercustomize.py

run this in terminal:

$ python -c "import site; site._script()"

if at the end you see something like this:

USER_BASE: '/home/USERNAME/.local' (exists)
USER_SITE: '/home/USERNAME/.local/lib/python2.7/site-packages' (exists)
ENABLE_USER_SITE: True

that means you can add a usercustomize.py module:

$ mkdir -p ~/.local/lib/python2.7/site-packages
$ touch ~/.local/lib/python2.7/site-packages/usercustomize.py

that will be included every time python is ran and so you can put this code in:

import __builtin__
try:
  import pout
  __builtin__.pout = pout
except ImportError:
  pass

Add pout to sitecustomize.py

run this in terminal:

$ python -c "import site; print site.getsitepackages()[0]

That should print out a good place to add a sitecustomize.py file. Create that file and include the pout import code in it.

Add pout to site.py

If none of the above options work for you, you can also actually edit Python’s site.py file. If you do this, you should most definitely only ever do it on your dev box in your dev environment, I would NOT do something like this on a production server:

1 - Find the site.py file for your python installation

You can find where your python installation lives through the Python shell:

$ python
>>> import sys
>>> sys.prefix
'/path/to/python/install'

2 - Go to that directory’s lib/pythonX.Y directory

So, if you were using Python 2.7, you would go to /path/to/python/install/lib/python2.7

3 - edit the site.py file

add this to somewhere near the end of the site.py file

try:
  import pout
  __builtin__.pout = pout
except ImportError:
  pass

4 - Now any python code will be able to use pout without you having to explicitely import it.

Read more, also here

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