Do you ever use print() or log() to debug your code? If so, ycecream, or y for short, will make printing debug information a lot sweeter.
And on top of that, you get some basic benchmarking functionality.
Installing ycecream with pip is easy.
$ pip install ycecream
or when you want to upgrade,
$ pip install ycecream --upgrade
Alternatively, ycecream.py can be juist copied into you current work directory from GitHub (https://github.com/salabim/ycecream).
No dependencies!
Have you ever printed variables or expressions to debug your program? If you've ever typed something like
print(add2(1000))
or the more thorough
print("add2(1000)", add2(1000)))
or (for Python >= 3.8 only):
print(f"{add2(1000) =}")
then y() is here to help. With arguments, y() inspects itself and prints
both its own arguments and the values of those arguments.
from ycecream import y
def add2(i):
return i + 2
y(add2(1000))
prints
y| add2(1000): 1002
Similarly,
from ycecream import y
class X:
a = 3
world = {"EN": "world", "NL": "wereld", "FR": "monde", "DE": "Welt"}
y(world, X.a)
prints
y| world: {"EN": "world", "NL": "wereld", "FR": "monde", "DE": "Welt"}, X.a: 3
Just give y() a variable or expression and you're done. Sweet, isn't it?
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 add2(i):
print("enter")
result = i + 2
print("exit")
return result
then y() helps here, too. Without arguments, y() inspects itself and
prints the calling line number and -if applicable- the file name and parent function.
from ycecream import y
def add2(i):
y()
result = i + 2
y()
return result
y(add2(1000))
prints something like
y| #3 in add2()
y| #5 in add2()
y| add2(1000): 1002
Just call y() and you're done. Isn't that sweet?
y() returns its argument(s), so y() can easily be inserted into
pre-existing code.
from ycecream import y
def add2(i):
return i + 2
b = y(add2(1000))
y(b)
prints
y| add2(1000): 1002
y| b: 1002
When you apply y() as a decorator to a function or method, both the entry and exit can be tracked.
The (keyword) arguments passed will be shown and upon return, the return value.
from ycecream import y
@y()
def mul(x, y):
return x * y
print(mul(5, 7))
prints
y| called mul(5, 7)
y| returned 35 from mul(5, 7) in 0.000006 seconds
35
It is possible to suppress the print-out of either the enter or the exit information with the show_enter and show_exit parameters, like:
from ycecream import y
@y(show_exit=False)
def mul(x, y):
return x * y
print(mul(5, 7))
prints
y| called mul(5, 7)
35
Note that it is possible to use y as a decorator without the parentheses, like
@y
def diode(x):
return 0 if x<0 else x
, but this might not work correctly when the def/class definition spawns more than one line. So, always use y() or
y(<parameters>) when used as a decorator.
If you decorate a function or method with y, you will be offered the duration between entry and exit (in seconds) as a bonus.
That opens the door to simple benchmarking, like:
from ycecream import y
import time
@y(show_enter=False,show_line_number=True)
def do_sort(i):
n = 10 ** i
x = sorted(list(range(n)))
return f"{n:9d}"
for i in range(8):
do_sort(i)
the ouput will show the effects of the population size on the sort speed:
y| #5 ==> returned ' 1' from do_sort(0) in 0.000027 seconds
y| #5 ==> returned ' 10' from do_sort(1) in 0.000060 seconds
y| #5 ==> returned ' 100' from do_sort(2) in 0.000748 seconds
y| #5 ==> returned ' 1000' from do_sort(3) in 0.001897 seconds
y| #5 ==> returned ' 10000' from do_sort(4) in 0.002231 seconds
y| #5 ==> returned ' 100000' from do_sort(5) in 0.024014 seconds
y| #5 ==> returned ' 1000000' from do_sort(6) in 0.257504 seconds
y| #5 ==> returned ' 10000000' from do_sort(7) in 1.553495 seconds
It is also possible to time any code by using y as a context manager, e.g.
with y():
time.sleep(1)
wil print something like
y| enter
y| exit in 1.000900 seconds
You can include parameters here as well:
with y(show_context=True, show_time=True):
time.sleep(1)
will print somethink like:
y| #8 @ 13:20:32.605903 ==> enter
y| #8 @ 13:20:33.609519 ==> exit in 1.003358 seconds
Finally, to help with timing code, you can request the current delta with
y().delta
or (re)set it with
y().delta = 0
So, e.g. to time a section of code:
y.delta = 0
time.sleep(1)
duration = y.delta
y(duration)
might print:
y| duration: 1.0001721999999997
For the configuration, it is important to realize that y is an instance of the ycecream._Y class, which has
a number of configuration attributes:
------------------------------------------------------
attribute alternative default
------------------------------------------------------
prefix p "y| "
output o "stderr"
serialize pprint.pformat
show_line_number sln False
show_time st False
show_delta sd False
show_enter se True
show_exit sx True
show_traceback stb False
sort_dicts *) sdi False
underscore_numbers *) un False
enabled e True
line_length ll 80
compact *) c False
indent i 1
depth de 1000000
wrap_indent wi " "
separator sep ", "
context_separator cs " ==> "
equals_separator es ": "
values_only vo False
value_only_for_fstrings voff False
return_none rn False
enforce_line_length ell False
decorator d False
context_manager cm False
delta dl 0
------------------------------------------------------
*) ignored under Python 2.7
It is perfectly ok to set/get any of these attributes directly, like
y.prefix = "==> "
print(y.prefix)
But, it is also possible to apply configuration directly in the call to y:
So, it is possible to say
from ycecream import y
y(12, prefix="==> ")
, which will print
==> 12
It is also possible to configure y permanently with the configure method.
y.configure(prefix="==> ")
y(12)
will print
==> 12
It is arguably easier to say:
y.prefix = "==> "
y(12)
or even
y.p = "==> "
y(12)
to print
==> 12
Yet another way to configure y is to get a new instance of y with y.new() and the required configuration:
z = y.new(prefix="==> ")
z(12)
will print
==> 12
Or, yet another possibility is to clone y (optionally with modified attributes):
yd1 = y.clone(show_date=True)
yd2 = y.clone()
yd2.configure(show_date=True)
After this yd1 and yd2 will behave similarly (but they are not the same!)
from ycecream import y
y('world', prefix='hello -> ')
prints
hello -> 'world'
prefix can be a function, too.
import time
from ycecream import y
def unix_timestamp():
return f"{int(time.time())} "
hello = "world"
y.configure(prefix=unix_timestamp)
y(hello)
prints
1613635601 hello: 'world'
This will allow the output to be handled by something else than the default (output being written to stderr).
The output attribute can be
- a callable that accepts at least one parameter (the text to be printed)
- a string or Path object that will be used as the filename
- a text file that is open for writing/appending
In the example below,
from ycecream import y
import sys
y(1, output=print)
y(2, output=sys.stdout
with open("test", "a+") as f:
y(3, output=f)
y(4, output="")
y| 1will be printed to stdouty| 2will be printed to stdouty| 3will be appended to the file testy| 4will disappear
As output may be any callable, you can even use this to automatically log any y output:
from ycecream import y
import logging
logging.basicConfig(level="INFO")
log = logging.getLogger("demo")
y.configure(output=log.info)
a = {1, 2, 3, 4, 5}
y(a)
a.remove(4)
y(a)
will print to stderr:
INFO:demo:y| a: {1, 2, 3, 4, 5}
INFO:demo:y| a: {1, 2, 3, 5}
Finally, you can specify the following strings:
"stderr" to print to stderr
"stdout" to print to stdout
"null" or "" to completely ignore (dummy) output
"logging.debug" to use logging.debug
"logging.info" to use logging.info
"logging.warning" to use logging.warning
"logging.error" to use logging.error
"logging.critical" to use logging.critical
E.g.
from ycecream import y
import sys
y.configure(output="stdout")
to print to stdout.
This will allow to specify how argument values are to be
serialized to displayable strings. The default is pformat (from pprint), but this can be changed to,
for example, to handle non-standard datatypes in a custom fashion.
The serialize function should accept at least one parameter.
The function can optionally accept the keyword arguments width and sort_dicts, compact, indent, underscore_numbers and depth.
from ycecream import y
def add_len(obj):
if hasattr(obj, "__len__"):
add = f" [len={len(obj)}]"
else:
add = ""
return f"{repr(obj)}{add}"
l = list(range(7))
hello = "world"
y(7, hello, l, serialize=add_len)
prints
y| 7, hello: 'world' [len=5], l: [0, 1, 2, 3, 4, 5, 6] [len=7]
If True, adds the y() call's line number and possible the filename and parent function to y()'s output.
from ycecream import y
y.configure(show_line_number=True)
def shout():
hello="world"
y(hello)
shout()
prints something like
y| #5 in shout() ==> hello: 'world'
If "no parent" or "n", the parent function will not be shown.
from ycecream import y
y.configure(show_line_number="n")
def shout():
hello="world"
y(hello)
shout()
prints something like
y| #5 ==> hello: 'world'
Note that if you call y without any arguments, the line number is always shown, regardless of the status show_line_number.
See below for an explanation of the information provided.
If True, adds the current time to y()'s output.
from ycecream import y
y.configure(show_time=True)
hello="world"
y(hello)
prints something like
y| @ 13:01:47.588125 ==> hello: 'world'
If True, adds the number of seconds since the start of the program to y()'s output.
from ycecream import y
import time
y.configure(show_delta=True)
french = "bonjour le monde"
english = "hallo world"
y(english)
time.sleep(1)
y(french)
prints something like
y| delta=0.088 ==> english: 'hallo world'
y| delta=1.091 ==> french: 'bonjour le monde'
When used as a decorator or context manager, by default, ycecream ouputs a line when the decorated the function is called or the context manager is entered.
With show_enter=False this line can be suppressed.
When used as a decorator or context manager, by default, ycecream ouputs a line when the decorated the function returned or the context manager is exited.
With show_exit=False this line can be suppressed.
When show_traceback is True, the ordinary output of y() will be followed by a printout of the traceback, similar to an error traceback.
from ycecream import y
y.show_traceback=True
def x():
y()
x()
x()
prints
y| #4 in x()
Traceback (most recent call last)
File "c:\Users\Ruud\Dropbox (Personal)\Apps\Python Ruud\ycecream\x.py", line 6, in <module>
x()
File "c:\Users\Ruud\Dropbox (Personal)\Apps\Python Ruud\ycecream\x.py", line 4, in x
y()
y| #4 in x()
Traceback (most recent call last)
File "c:\Users\Ruud\Dropbox (Personal)\Apps\Python Ruud\ycecream\x.py", line 7, in <module>
x()
File "c:\Users\Ruud\Dropbox (Personal)\Apps\Python Ruud\ycecream\x.py", line 4, in x
y()
The show_traceback functionality is also available when y is used as a decorator or context manager.
This attribute is used to specify the line length (for wrapping). The default is 80. Ycecream always tries to keep all output on one line, but if it can't it will wrap:
d = dict(a1=1,a2=dict(a=1,b=1,c=3),a3=list(range(10)))
y(d)
y(d, line_length=120)
prints
y|
d:
{'a1': 1,
'a2': {'a': 1, 'b': 1, 'c': 3},
'a3': [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]}
y| d: {'a1': 1, 'a2': {'a': 1, 'b': 1, 'c': 3}, 'a3': [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]}
This attribute is used to specify the compact parameter for pformat (see the pprint documentation
for details). compact is False by default.
a = 9 * ["0123456789"]
y(a)
y(a, compact=True)
prints
y|
a:
['0123456789',
'0123456789',
'0123456789',
'0123456789',
'0123456789',
'0123456789',
'0123456789',
'0123456789',
'0123456789']
y|
a:
['0123456789', '0123456789', '0123456789', '0123456789', '0123456789',
'0123456789', '0123456789', '0123456789', '0123456789']
Note that compact is ignored under Python 2.7.
This attribute is used to specify the indent parameter for pformat (see the pprint documentation
for details). indent is 1 by default.
s = "01234567890012345678900123456789001234567890"
y( [s, [s]])
y( [s, [s]], indent=4)
prints
y|
[s, [s]]:
['01234567890012345678900123456789001234567890',
['01234567890012345678900123456789001234567890']]
y|
[s, [s]]:
[ '01234567890012345678900123456789001234567890',
['01234567890012345678900123456789001234567890']]
This attribute is used to specify the depth parameter for pformat (see the pprint documentation
for details). depth is 1000000 by default.
s = "01234567890012345678900123456789001234567890"
y([s,[s,[s,[s,s]]]])
y([s,[s,[s,[s,s]]]], depth=3)
prints
y|
[s,[s,[s,[s,s]]]]:
['01234567890012345678900123456789001234567890',
['01234567890012345678900123456789001234567890',
['01234567890012345678900123456789001234567890',
['01234567890012345678900123456789001234567890',
'01234567890012345678900123456789001234567890']]]]
y|
[s,[s,[s,[s,s]]]]:
['01234567890012345678900123456789001234567890',
['01234567890012345678900123456789001234567890',
['01234567890012345678900123456789001234567890', [...]]]]
This specifies the indent string if the output does not fit in the line_length (has to be wrapped). Rather than a string, wrap_indent can be also be an integer, in which case the wrap_indent will be that amount of blanks. The default is 4 blanks.
E.g.
d = dict(a1=1,a2=dict(a=1,b=1,c=3),a3=list(range(10)))
y(d, wrap_indent=" ")
y(d, wrap_indent="....")
y(d, wrap_indent=2)
prints
y|
d:
{'a1': 1,
'a2': {'a': 1, 'b': 1, 'c': 3},
'a3': [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]}
y|
....d:
........{'a1': 1,
........ 'a2': {'a': 1, 'b': 1, 'c': 3},
........ 'a3': [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]}
y|
d:
{'a1': 1,
'a2': {'a': 1, 'b': 1, 'c': 3},
'a3': [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]}
Can be used to disable the output:
from ycecream import y
y.configure(enabled=False)
s = 'the world is '
y(s + 'perfect.')
y.configure(enabled=True)
y(s + 'on fire.')
prints
y| s + 'on fire.': 'the world is on fire.'
and nothing about a perfect world.
By default, ycecream does not sort dicts (printed by pprint). However, it is possible to get the default pprint behaviour (i.e. sorting dicts) with the sorted_dicts attribute:
world = {"EN": "world", "NL": "wereld", "FR": "monde", "DE": "Welt"}
y(world))
y(world, sort_dicts=False)
y(world, sort_dicts=True)
prints
y| world: {'EN': 'world', 'NL': 'wereld', 'FR': 'monde', 'DE': 'Welt'}
y| world: {'EN': 'world', 'NL': 'wereld', 'FR': 'monde', 'DE': 'Welt'}
y| world: {'DE': 'Welt', 'EN': 'world', 'FR': 'monde', 'NL': 'wereld'}
Note that sort_dicts is ignored under Python 2.7, i.e. dicts are always sorted.
By default, ycecream does not add underscores in big numberss (printed by pprint). However, it is possible to get the default pprint behaviour with the underscore_numbers attribute:
numbers = dict(one= 1, thousand= 1000, million=1000000, x1234567890= 1234567890)
y(numbers)
y(numbers, underscore_numbers=True)
y(numbers, un=False)
prints
y| numbers: {'one': 1, 'thousand': 1000, 'million': 1000000, 'x1234567890': 1234567890}
y| numbers: {'one': 1, 'thousand': 1_000, 'million': 1_000_000, 'x1234567890': 1_234_567_890}
y| numbers: {'one': 1, 'thousand': 1000, 'million': 1000000, 'x1234567890': 1234567890}
Note that underscore_numbers is ignored under Python 2.7, i.e. numbers are never underscored.
By default, pairs (on one line) are separated by , .
It is possible to change this with the attribute separator:
a="abcd"
b=1
c=1000
d=list("ycecream")
y(a,(b,c),d)
y(a,(b,c),d, separator=" | ")
prints
y| a: 'abcd', (b,c): (1, 1000), d: ['y', 'c', 'e', 'c', 'r', 'e', 'a', 'm']
y| a: 'abcd' | (b,c): (1, 1000) | d: ['y', 'c', 'e', 'c', 'r', 'e', 'a', 'm']
By default the line_number, time and/or delta are followed by ==>.
It is possible to change this with the attribute context_separator:
a="abcd"
y(a)
y(a, show_time=True, context_separator = ' \u279c ')
prints:
y| @ 12:56:11.341650 ==> a: 'abcd'
y| @ 12:56:11.485567 âžś a: 'abcd'
By default name of a variable and its value are separated by : .
It is possible to change this with the attribute equals_separator:
a="abcd"
y(a)
y(a, equals_separator = ' == ")
prints:
y| a: 'abcd'
y| a == 'abcd'
If False (the default), both the left-hand side (if possible) and the value will be printed. If True, the left_hand side will be suppressed:
hello = "world"
y(hello, 2 * hello)
y(hello, 2 * hello, values_only=True)
prints
y| hello: 'world', 2 * hello = 'worldworld'
y| 'world', 'worldworld'
The values=True version of y can be seen as a supercharged print/pprint.
If False (the default), both the original f-string and the value will be printed for f-strings. If True, the left_hand side will be suppressed in case of an f-string:
x = 12.3
y(f"{x:0.3e}")
y.values_only_for_fstrings = True
y(f"{x:0.3e}")
prints
y| f"{x:0.3e}": '1.230e+01'
y| '1.230e+01'
Note that if values_only is True, f-string will be suppressed, regardless of values_only_for_fstrings.
Normally, y()returns the values passed directly, which is usually fine. However, when used in a notebook
or REPL, that value will be shown, and that can be annoying. Therefore, if return_noneis True, y()will
return None and thus not show anything.
a = 3
print(y(a, a + 1))
y.configure(return_none=True)
print(y(a, a + 1))
prints
y| (3, 4)
(3, 4)
y| (3, 4)
None
If enforce_line_length is True, all output lines are explicitely truncated to the given line_length, even those that are not truncated by pformat.
The delta attribute can be used to (re)set the current delta, e.g.
y.configure(dl=0)
print(y.delta)
prints a value that slightly more than 0.
Normally, an ycecream instance can be used as to show values, as a decorator and as a context manager.
However, when used from a REPL the usage as a decorator can't be detected properly and in that case,
specify decorator=True. E.g.
>>>@y(decorator=True)
>>>def add2(x):
>>> return x + 2
>>>print(add2(10))
y| called add2(10)
y| returned 12 from add2(10) in 0.000548 seconds
12
The decorator attribute is also required when using y() as a decorator
witb fast disabling (see below).
y.enabled([])
@y()
def add2(x):
return x + 2
would fail withTypeError: 'NoneType' object is not callable, but
y.enabled([])
@y(decorator=True)
def add2(x):
return x + 2
will run correctly.
Normally, an ycecream instance can be used as to show values, as a decorator and as a context manager.
However, when used from a REPL the usage as a context manager can't be detected properly and in that case,
specify context_manager=True. E.g.
>>>with y(context_manager=True)
>>> pass
y| enter
y| exit in 0.008644 seconds
The context_manager attribute is also required when using y(): as a context manager
with fast disabling (see below).
y.enabled([])
with y:
pass
would fail with AttributeError: __enter__, but
y.enabled([])
with y(context_manager=True):
pass
will run correctly.
If provided is False, all output for this call will be suppressed. If provided is True, output will be generated as usual (obeying the enabled attribute).
x = 1
y("should print", provided=x > 0)
y("should not print", provided=x < 0)
This will print
should print
y(*args, as_str=True) is like y(*args) but the output is returned as a string instead
of written to output.
from ycecream import y
hello = "world"
s = y(hello, as_str=True)
print(s, end="")
prints
y| hello: 'world'
Note that if enabled=False, the call will return the null string ("").
from ycecream import y
yd = y.fork(show_delta=True)
y(1)
yd(2)
y.enabled = False
y(3)
yd(4)
y.enabled = True
y(5)
yd(6)
print(y.enabled)
prints
y| 1
y| delta=0.011826 ==> 2
y| 5
y| delta=0.044893 ==> 6
True
Of course y() continues to return its arguments when disabled, of course.
It is also possible to suppress output with the provided attribute (see above).
When output is disabled, either via y.configure(enbabled=False) or ycecream.enable = False,
ycecream still has to check for usage as a decorator or context manager, which can be rather time
consuming.
In order to speed up a program with disabled ycecream calls, it is possible to specify
y.configure(enabled=[]), in which case y will always just return
the given arguments. If ycecream is disabled this way, usage as a @y() decorator or as a with y():
context manager will raise a runtime error, though. The @y decorator without parentheses will
not raise any exception, though.
To use y as a decorator and still have fast disabling:
y.configure(enabled=[])
@y(decorator=True):
def add2(x):
return x + 2
x34 = add2(30)
And, similarly, to use y as a context manager combined with fast disabling:
y.configure(enabled=[])
with @y(context_manager=True):
pass
The table below shows it all.
-------------------------------------------------------------------------------
enabled=True enabled=False enabled=[]
-------------------------------------------------------------------------------
execution speed normal normal fast
y() normal no output no output
@y normal no output no output
y(decorator=True) normal no output no output
y(context_manager=True) normal no output no output
@y() normal no output TypeError
with y(): normal no output AttributeError/TypeError
y(as_str=True) normal "" ""
-------------------------------------------------------------------------------
Ycecream has a method assert_ that works like assert, but can be enabled or disabled with the enabled flag.
temperature = -1
y.assert_(temperature > 0)
This will raise an AttributeError.
But
y.enabled = False
temperature = -1
y.assert_(temperature > 0)
will not.
Note that with the attribute propagation method, you can in effect have a layered assert system.
When show_line_number is True or y() is used without any parameters, the output will contain the line number like:
y| #3 ==> a: 'abcd'
If the line resides in another file than the main file, the filename (without the path) will be shown as well:
y| #30[foo.py] ==> foo: 'Foo'
And finally when used in a function or method, that function/method will be shown as well:
y| #456[foo.py] in square_root ==> x: 123
The parent function can be suppressed by setting show_line_number or sln to "n" or "no parent".
It can be useful to configure ycecream at import time. This can be done by providing a ycecream.json file which
can contain any attribute configuration overriding the standard settings.
E.g. if there is an ycecream.json file with the following contents
{
"o": "stdout",
"show_time": true,
"line_length": 120`
'compact' : true
}
in the same folder as the application, this program:
from ycecream import y
hello = "world"
y(hello)
will print to stdout (rather than stderr):
y| @ 14:53:41.392190 ==> hello: 'world'
At import time the sys.path will be searched for, in that order, to find an ycecream.json file and use that. This mean that
you can place an ycecream.json file in the site-packages folder where ycecream is installed to always use
these modified settings.
Please observe that json values are slightly different from their Python equivalents:
-------------------------------
Python json
-------------------------------
True true
False false
None none
strings always double quoted
-------------------------------
Note that not-specified attributes will remain the default settings.
For obvious reasons, it is not possible to specify serialize in an ycecream.json file.
Normally, only the y() object is used.
It can be useful to have multiple instances, e.g. when some of the debugging has to be done with context information and others requires an alternative prefix.
THere are several ways to obtain a new instance of ycecream:
-
by using
y.new()With this a new ycecream object is created with the default attributes and possibly ycecream.json overrides.
-
by using
y.new(ignore_json=True)With this a new ycecreamobject is created with the default attibutes. Any ycecream.json files asre ignored.
-
by using
y.fork()With this a new ycecream object is created with the same attributes as the object it is created ('the parent') from. Note that any non set attributes are copied (propagated) from the parent.
-
by using
y.clone(), which copies all attributes from y()With this a new ycecream object is created with the same attributes as the object it is created ('the parent') from. Note that the attributes are not propagated from the parent, in this case.
-
with
y()used as a context manager
In either case, attributes can be added to override the default ones.
from ycecream import y
y_with_line_number = y.fork(show_line_number=True)
y_with_new_prefix = y.new(prefix="==> ")
y_with_new_prefix_and_time = y_with_new_prefix.clone(show_time=True)
hello="world"
y_with_line_number(hello)
y_with_new_prefix(hello)
y_with_new_prefix_and_time(hello)
y.equals_separator = " == " # this affects only the forked objects
y_with_line_number(hello)
y_with_new_prefix(hello)
y_with_new_prefix_and_time(hello)
with y(prefix="ycm ") as ycm:
ycm(hello)
y(hello)
prints
y| #6 ==> hello: 'world'
==> hello: 'world'
==> @ 09:55:10.883732 ==> hello: 'world'
y| #10 ==> hello == 'world'
==> hello: 'world'
==> @ 09:55:10.910717 ==> hello: 'world'
ycm enter
ycm hello == 'world'
y| hello == 'world'
ycm exit in 0.017686 seconds
With y.new(ignore_json=True) an instance of y without having applied any json configuration file will be returned. That can be useful when guaranteeing the same output in several setups.
Suppose we have an ycecream.json file in the current directory with the contents
{prefix="==>"}
Then
y_post_json = y.new()
y_ignore_json = y.new(ignore_json=True)
hello = "world"
y(hello)
y_post_json(hello)
y_ignore_json(hello)
prints
==>hello: 'world'
==>hello: 'world'
y| hello: 'world'
On GitHub is a file test_ycecream.py that tests (and thus also demonstrates) most of the functionality
of ycecream.
It is very useful to have a look at the tests to see the features (some may be not covered (yet) in this readme).
Ycecream may be used in a REPL, but with limited functionality:
- all arguments are just presented as such, i.e. no left-hand side, e.g.
>> hello = "world" >>> y(hello, hello * 2) y| 'hello', 'hellohello' ('hello', 'hellohello') - line numbers are never shown
- use as a decorator is only supported when you used as
y(decorator=True)ory(d=1) - use as a context manager is only supported when used as
y(context_manager=True)ory(cm=1)
Sometimes, it is not suitable to use the name y in a program, e.g. when dealing with coordinates x, y and z.
In that case, it is possible to use yc instead
from ycecream import yc
The yc object is a fork of y with the prefix "yc| ". That means that attributes of y are propagated to yc, unless overridden.
Of course, it is also possible to use
from ycecream import y as yy
or
yy = y.new()
or
yy = y.new(prefix="yy| ")
With install ycecream from github.py, you can install the ycecream.py directly from GitHub to the site packages (as if it was a pip install).
With install ycecream.py, you can install the ycecream.py in your current directory to the site packages (as if it was a pip install).
Both files can be found in the GitHub repository (https://github.com/salabim/ycecream).
It is not possible to use ycecream:
- from a frozen application (e.g. packaged with PyInstaller)
- when the underlying source code has changed during execution
Although not important for using the package, here are some implementation details:
- ycecream.py contains the complete source of the asttokens and executing packages, in order to offer the required source lookups, without any dependencies
- ycecream.py contains the complete source of pprint as of Python 3.8 in order to support the sort_dicts and underscore_numbers parameter, Under Python 2.7 these are ignored and the pprint module from the standard library is used.
- in order to support using y() as a decorator and a context manager, ycecream caches the complete source of any source file that uses y()
The ycecream pacakage is inspired by the IceCream package, but is a nearly complete rewrite. See https://github.com/gruns/icecream
Many thanks to the author Ansgar Grunseid / grunseid.com / grunseid@gmail.com .
The ycecream module was originally a fork of IceCream, but has many differences:
----------------------------------------------------------------------------------------
characteristic ycecream IceCream
----------------------------------------------------------------------------------------
platform Python 2.7, >=3.6, PyPy Python 2.7, >=3.5, PyPy
default name y (or yc) ic
dependencies none many
number of files 1 several
usable without installation yes no
can be used as a decorator yes no
can be used as a context manager yes no
can show traceback yes no
PEP8 (Pythonic) API yes no
sorts dicts no by default, optional yes
supports compact, indent,
and underscore_numbers
parameters of pprint yes no
use from a REPL limited functionality no
external configuration via json file no
observes line_length correctly yes no
benchmarking functionality yes no
suppress f-strings at left hand optional no
indentation 4 blanks (overridable) dependent on length of prefix
forking and cloning yes no
test script pytest unittest
colourize no yes (can be disabled)
----------------------------------------------------------------------------------------
*) sort_dicts, compact and underscore_numbers are ignored under Python 2.7
If you like ycecream
