I wrote this before I learnt about Snoop: https://github.com/alexmojaki/snoop a much polished version of the same concept and implementation with an additional set of debug tools.
Tracelogger
Tag your functions with the @tracelogger decorator to be logged line-by-line.
Optionally provide a function as the printer argument that takes the local variable dictionary and returns a string. This allows the customisation of which variables and how you want to print at each line. See the example with the provided names_printer function that only prints a selected set of variables.
The second width parameter determines the maximum character number for each line of code defaulting to 80.
from tracelogger import tracelogger, names_printer
@tracelogger(width=30)
def second_test_function(x):
y = x**2
return y
@tracelogger(printer=lambda locals_: names_printer(locals_=locals_, names=['k', 'b']), width=30)
def first_test_function(a, b):
c = a + b
for k in range(5):
if k % 2 == 0:
b += k
else:
c += k
second_test_function(c)
return a, b, c
a, b, c = first_test_function(a=10, b=20)
This will print the following:
Entering function: first_test_function
c = a + b locals: b=20
for k in range(5): locals: b=20
if k % 2 == 0: locals: b=20, k=0
b += k locals: b=20, k=0
for k in range(5): locals: b=20, k=0
if k % 2 == 0: locals: b=20, k=1
c += k locals: b=20, k=1
second_test_function(c) locals: b=20, k=1
Entering function: second_test_function
y = x**2 locals: x=31
return y locals: x=31, y=961
return y locals: x=31, y=961
Returning from: second_test_function() to: first_test_function()
for k in range(5): locals: b=20, k=1
if k % 2 == 0: locals: b=20, k=2
b += k locals: b=20, k=2
for k in range(5): locals: b=22, k=2
if k % 2 == 0: locals: b=22, k=3
c += k locals: b=22, k=3
second_test_function(c) locals: b=22, k=3
Entering function: second_test_function
y = x**2 locals: x=34
return y locals: x=34, y=1156
return y locals: x=34, y=1156
Returning from: second_test_function() to: first_test_function()
for k in range(5): locals: b=22, k=3
if k % 2 == 0: locals: b=22, k=4
b += k locals: b=22, k=4
for k in range(5): locals: b=26, k=4
return a, b, c locals: b=26, k=4
return a, b, c locals: b=26, k=4
Returning from: first_test_function() to: None
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I used the following StackOverflow threads as sources, many thanks to their authors:
https://stackoverflow.com/questions/22362940/inspect-code-of-next-line-in-python