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gruns / icecream

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 Never use print() to debug again.

MIT License
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@gruns
gruns switch to more apt emdash
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a2c8f5b Mar 10, 2021
switch to more apt emdash
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icecream
icecream v2.1.0
Jan 27, 2021
tests
determine whether an argument and value are the same with
ast.literal...
Jan 27, 2021
.gitignore
The future of print debugging.
Feb 13, 2018
.travis.yml
Drop support for Python 3.4
Oct 25, 2019
LICENSE.txt
The future of print debugging.
Feb 13, 2018
MANIFEST.in
Include README.md in source distributions.
May 15, 2019
README.md
switch to more apt emdash
Mar 10, 2021
changelog.txt
add newline to homogenize whitespace
Jan 27, 2021
logo.svg
Rename icon.svg to the more apposite logo.svg.
Aug 28, 2018
setup.cfg
Publish both a source distribution and a Wheel to PyPi.
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setup.py
Update slogan.
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tox.ini
Drop support for Python 3.4
Oct 25, 2019
View code
 IceCream -- Never use print() to debug again Inspect Variables
Inspect Execution Return Value Miscellaneous Import Tricks
Configuration Installation IceCream in Other Languages

README.md

                               icecream

         [6874747073] [6874747073] [6874747073] [6874747073]

 IceCream -- Never use print() to debug again

Do you ever use print() or log() to debug your code? Of course you
do. IceCream, or ic for short, makes print debugging a little
sweeter.

IceCream is well tested, permissively licensed, and supports Python
2, Python 3, PyPy2, and PyPy3.

 Inspect Variables

Have you ever printed variables or expressions to debug your program?
If you've ever typed something like

print(foo('123'))

or the more thorough

print("foo('123')", foo('123'))

then ic() is here to help. With arguments, ic() inspects itself and
prints both its own arguments and the values of those arguments.

from icecream import ic

def foo(i):
    return i + 333

ic(foo(123))

Prints

ic| foo(123): 456

Similarly,

d = {'key': {1: 'one'}}
ic(d['key'][1])

class klass():
    attr = 'yep'
ic(klass.attr)

Prints

ic| d['key'][1]: 'one'
ic| klass.attr: 'yep'

Just give ic() a variable or expression and you're done. Easy.

 Inspect Execution

Have you ever used print() to determine which parts of your program
are executed, and in which order they're executed? For example, if
you've ever added print statements to debug code like

def foo():
    print(0)
    first()

    if expression:
        print(1)
        second()
    else:
        print(2)
        third()

then ic() helps here, too. Without arguments, ic() inspects itself
and prints the calling filename, line number, and parent function.

from icecream import ic

def foo():
    ic()
    first()

    if expression:
        ic()
        second()
    else:
        ic()
        third()

Prints

ic| example.py:4 in foo()
ic| example.py:11 in foo()

Just call ic() and you're done. Simple.

 Return Value

ic() returns its argument(s), so ic() can easily be inserted into
pre-existing code.

>>> a = 6
>>> def half(i):
>>>     return i / 2
>>> b = half(ic(a))
ic| a: 6
>>> ic(b)
ic| b: 3

 Miscellaneous

ic.format(*args) is like ic() but the output is returned as a string
instead of written to stderr.

>>> from icecream import ic
>>> s = 'sup'
>>> out = ic.format(s)
>>> print(out)
ic| s: 'sup'

Additionally, ic()'s output can be entirely disabled, and later
re-enabled, with ic.disable() and ic.enable() respectively.

from icecream import ic

ic(1)

ic.disable()
ic(2)

ic.enable()
ic(3)

Prints

ic| 1: 1
ic| 3: 3

ic() continues to return its arguments when disabled, of course; no
existing code with ic() breaks.

 Import Tricks

To make ic() available in every file without needing to be imported
in every file, you can install() it. For example, in a root A.py:

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

from icecream import install
install()

from B import foo
foo()

and then in B.py, which is imported by A.py, just call ic():

# -*- coding: utf-8 -*-

def foo():
    x = 3
    ic(x)

install() adds ic() to the builtins module, which is shared amongst
all files imported by the interpreter. Similarly, ic() can later be
uninstall()ed, too.

ic() can also be imported in a manner that fails gracefully if
IceCream isn't installed, like in production environments (i.e. not
development). To that end, this fallback import snippet may prove
useful:

try:
    from icecream import ic
except ImportError:  # Graceful fallback if IceCream isn't installed.
    ic = lambda *a: None if not a else (a[0] if len(a) == 1 else a)  # noqa

 Configuration

ic.configureOutput(prefix, outputFunction, argToStringFunction,
includeContext) can be used to adopt a custom output prefix (the
default is ic| ), change the output function (default is to write to
stderr), customize how arguments are serialized to strings, and/or
include the ic() call's context (filename, line number, and parent
function) in ic() output with arguments.

>>> from icecream import ic
>>> ic.configureOutput(prefix='hello -> ')
>>> ic('world')
hello -> 'world'

prefix can optionally be a function, too.

>>> import time
>>> from icecream import ic
>>>
>>> def unixTimestamp():
>>>     return '%i |> ' % int(time.time())
>>>
>>> ic.configureOutput(prefix=unixTimestamp)
>>> ic('world')
1519185860 |> 'world': 'world'

outputFunction, if provided, is called with ic()'s output instead of
that output being written to stderr (the default).

>>> import logging
>>> from icecream import ic
>>>
>>> def warn(s):
>>>     logging.warning(s)
>>>
>>> ic.configureOutput(outputFunction=warn)
>>> ic('eep')
WARNING:root:ic| 'eep': 'eep'

argToStringFunction, if provided, is called with argument values to
be serialized to displayable strings. The default is PrettyPrint's
pprint.pformat(), but this can be changed to, for example, handle
non-standard datatypes in a custom fashion.

>>> from icecream import ic
>>>
>>> def toString(obj):
>>>    if isinstance(obj, str):
>>>        return '[!string %r with length %i!]' % (obj, len(obj))
>>>    return repr(obj)
>>>
>>> ic.configureOutput(argToStringFunction=toString)
>>> ic(7, 'hello')
ic| 7: 7, 'hello': [!string 'hello' with length 5!]

includeContext, if provided and True, adds the ic() call's filename,
line number, and parent function to ic()'s output.

>>> from icecream import ic
>>> ic.configureOutput(includeContext=True)
>>>
>>> def foo():
>>>   ic('str')
>>> foo()
ic| example.py:12 in foo()- 'str': 'str'

includeContext is False by default.

 Installation

Installing IceCream with pip is easy.

$ pip install icecream

 IceCream in Other Languages

IceCream should be enjoyed with every language.

  * Dart: icecream
  * Rust: icecream-rs
  * Node.js: node-icecream
  * C++: IceCream-Cpp
  * PHP: icecream-php
  * Go: icecream-go
  * Ruby: Ricecream
  * Java: icecream-java

If you'd like a similar ic() function in your favorite language,
please open a pull request! IceCream's goal is to sweeten print
debugging with a handy-dandy ic() function in every language.

About

 Never use print() to debug again.

Topics

python debugging library python3 debug print inspects debugging-tool

Resources

Readme

License

MIT License

Releases 3

 
IceCream v2.0.0. Latest
Oct 26, 2019
+ 2 releases

Packages 0

No packages published

Contributors 11

  * @gruns
  * @alexmojaki
  * @ss18
  * @nodai2hITC
  * @renatoGarcia
  * @miggaiowski
  * @baopham
  * @ntzm
  * @Akshay-Thakare
  * @jmerle
  * @chang

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