ch11

ch11/assertions.py

@@ -0,0 +1,28 @@
+# assertions.py
+mylist = [1, 2, 3]  # pretend this comes from an external source
+
+assert 4 == len(mylist)  # this will break
+
+for position in range(4):
+    print(mylist[position])
+
+
+"""
+$ python assertions.py
+Traceback (most recent call last):
+  File "assertions.py", line 4, in <module>
+    assert 4 == len(mylist)  # this will break
+AssertionError
+"""
+
+# asserts with message
+assert 4 == len(mylist), f"Mylist has {len(mylist)} elements"
+
+
+"""
+$ python assertions.py
+Traceback (most recent call last):
+  File "assertions.py", line 19, in <module>
+    assert 4 == len(mylist), f"Mylist has {len(mylist)} elements"
+AssertionError: Mylist has 3 elements
+"""

ch11/custom.py

@@ -0,0 +1,20 @@
+# custom.py
+def debug(*msg, print_separator=True):
+    print(*msg)
+    if print_separator:
+        print('-' * 40)
+
+
+debug('Data is ...')
+debug('Different', 'Strings', 'Are not a problem')
+debug('After while loop', print_separator=False)
+
+
+"""
+$ python custom.py
+Data is ...
+----------------------------------------
+Different Strings Are not a problem
+----------------------------------------
+After while loop
+"""

ch11/custom_timestamp.py

@@ -0,0 +1,32 @@
+# custom_timestamp.py
+from time import sleep
+
+
+def debug(*msg, timestamp=[None]):
+    print(*msg)
+    from time import time  # local import
+    if timestamp[0] is None:
+        timestamp[0] = time()  #1
+    else:
+        now = time()
+        print(
+            ' Time elapsed: {:.3f}s'.format(now - timestamp[0])
+        )
+        timestamp[0] = now  #2
+
+
+debug('Entering nasty piece of code...')
+sleep(.3)
+debug('First step done.')
+sleep(.5)
+debug('Second step done.')
+
+
+"""
+$ python custom_timestamp.py
+Entering nasty piece of code...
+First step done.
+ Time elapsed: 0.300s
+Second step done.
+ Time elapsed: 0.500s
+"""

ch11/log.py

@@ -0,0 +1,21 @@
+# log.py
+import logging
+
+logging.basicConfig(
+    filename='ch11.log',
+    level=logging.DEBUG,
+    format='[%(asctime)s] %(levelname)s: %(message)s',
+    datefmt='%m/%d/%Y %I:%M:%S %p')
+
+mylist = [1, 2, 3]
+logging.info('Starting to process `mylist`...')
+
+for position in range(4):
+    try:
+        logging.debug(
+            'Value at position %s is %s', position, mylist[position]
+        )
+    except IndexError:
+        logging.exception('Faulty position: %s', position)
+
+logging.info('Done processing `mylist`.')

ch11/pdebugger.py

@@ -0,0 +1,23 @@
+# pdebugger.py
+# d comes from a JSON payload we don't control
+d = {'first': 'v1', 'second': 'v2', 'fourth': 'v4'}
+# keys also comes from a JSON payload we don't control
+keys = ('first', 'second', 'third', 'fourth')
+
+def do_something_with_value(value):
+    print(value)
+
+for key in keys:
+    do_something_with_value(d[key])
+
+print('Validation done.')
+
+"""
+$ python pdebugger.py
+v1
+v2
+Traceback (most recent call last):
+  File "pdebugger.py", line 11, in <module>
+    do_something_with_value(d[key])
+KeyError: 'third'
+"""

ch11/pdebugger_pdb.py

@@ -0,0 +1,45 @@
+# pdebugger_pdb.py
+# d comes from a JSON payload we don't control
+d = {'first': 'v1', 'second': 'v2', 'fourth': 'v4'}
+# keys also comes from a JSON payload we don't control
+keys = ('first', 'second', 'third', 'fourth')
+
+def do_something_with_value(value):
+    print(value)
+
+
+import pdb
+pdb.set_trace()
+
+# or:
+# breakpoint()
+
+
+for key in keys:
+    do_something_with_value(d[key])
+
+print('Validation done.')
+
+
+"""
+$ python pdebugger_pdb.py
+[0] > pdebugger_pdb.py(17)<module>()
+-> for key in keys:
+(Pdb++) l
+ 17
+ 18  -> for key in keys:  # breakpoint comes in
+ 19         do_something_with_value(d[key])
+ 20
+
+(Pdb++) keys  # inspecting the keys tuple
+('first', 'second', 'third', 'fourth')
+(Pdb++) d.keys()  # inspecting keys of `d`
+dict_keys(['first', 'second', 'fourth'])
+(Pdb++) d['third'] = 'placeholder'  # add missing item
+(Pdb++) c  # continue
+v1
+v2
+placeholder
+v4
+Validation done.
+"""

ch11/profiling/triples.py

@@ -0,0 +1,37 @@
+
+def calc_triples(mx):
+    triples = []
+    for a in range(1, mx + 1):
+        for b in range(a, mx + 1):
+            hypotenuse = calc_hypotenuse(a, b)
+            if is_int(hypotenuse):
+                triples.append((a, b, int(hypotenuse)))
+    return triples
+
+
+def calc_hypotenuse(a, b):
+    return (a**2 + b**2) ** .5
+
+
+def is_int(n):  # n is expected to be a float
+    return n.is_integer()
+
+
+triples = calc_triples(1000)
+
+"""
+$ python -m cProfile profiling/triples.py
+1502538 function calls in 0.489 seconds
+
+Ordered by: standard name
+
+   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
+   500500    0.282    0.000    0.282    0.000 triples.py:13(calc_hypotenuse)
+   500500    0.065    0.000    0.086    0.000 triples.py:17(is_int)
+        1    0.000    0.000    0.489    0.489 triples.py:3(<module>)
+        1    0.121    0.121    0.489    0.489 triples.py:3(calc_triples)
+        1    0.000    0.000    0.489    0.489 {built-in method builtins.exec}
+     1034    0.000    0.000    0.000    0.000 {method 'append' of 'list' objects}
+        1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler' objects}
+   500500    0.021    0.000    0.021    0.000 {method 'is_integer' of 'float' objects}
+"""

ch11/profiling/triples_v2.py

@@ -0,0 +1,37 @@
+
+def calc_triples(mx):
+    triples = []
+    for a in range(1, mx + 1):
+        for b in range(a, mx + 1):
+            hypotenuse = calc_hypotenuse(a, b)
+            if is_int(hypotenuse):
+                triples.append((a, b, int(hypotenuse)))
+    return triples
+
+
+def calc_hypotenuse(a, b):
+    return (a*a + b*b) ** .5
+
+
+def is_int(n):  # n is expected to be a float
+    return n.is_integer()
+
+
+triples = calc_triples(1000)
+
+"""
+$ python -m cProfile profiling/triples_v2.py
+         1502538 function calls in 0.288 seconds
+
+   Ordered by: standard name
+
+   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
+   500500    0.084    0.000    0.084    0.000 triples_v2.py:13(calc_hypotenuse)
+   500500    0.064    0.000    0.084    0.000 triples_v2.py:17(is_int)
+        1    0.000    0.000    0.288    0.288 triples_v2.py:3(<module>)
+        1    0.120    0.120    0.288    0.288 triples_v2.py:3(calc_triples)
+        1    0.000    0.000    0.288    0.288 {built-in method builtins.exec}
+     1034    0.000    0.000    0.000    0.000 {method 'append' of 'list' objects}
+        1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler' objects}
+   500500    0.020    0.000    0.020    0.000 {method 'is_integer' of 'float' objects}
+"""

ch11/profiling/triples_v3.py

@@ -0,0 +1,36 @@
+
+def calc_triples(mx):
+    triples = []
+    for a in range(1, mx + 1):
+        for b in range(a, mx + 1):
+            hypotenuse = calc_hypotenuse(a, b)
+            if is_int(hypotenuse):
+                triples.append((a, b, int(hypotenuse)))
+    return triples
+
+
+def calc_hypotenuse(a, b):
+    return (a*a + b*b) ** .5
+
+
+def is_int(n):
+    return n == int(n)
+
+
+triples = calc_triples(1000)
+
+"""
+$ python -m cProfile profiling/triples_v3.py
+         1002038 function calls in 0.269 seconds
+
+   Ordered by: standard name
+
+   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
+   500500    0.084    0.000    0.084    0.000 triples_v3.py:13(calc_hypotenuse)
+   500500    0.068    0.000    0.068    0.000 triples_v3.py:17(is_int)
+        1    0.000    0.000    0.269    0.269 triples_v3.py:3(<module>)
+        1    0.116    0.116    0.269    0.269 triples_v3.py:3(calc_triples)
+        1    0.000    0.000    0.269    0.269 {built-in method builtins.exec}
+     1034    0.000    0.000    0.000    0.000 {method 'append' of 'list' objects}
+        1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler' objects}
+"""

ch11/requirements.in

@@ -0,0 +1 @@
+pdbpp

ch11/requirements.txt

@@ -0,0 +1,16 @@
+#
+# This file is autogenerated by pip-compile with python 3.9
+# To update, run:
+#
+#    pip-compile requirements.in
+#
+fancycompleter==0.9.1
+    # via pdbpp
+pdbpp==0.10.3
+    # via -r requirements.in
+pygments==2.9.0
+    # via pdbpp
+pyrepl==0.9.0
+    # via fancycompleter
+wmctrl==0.4
+    # via pdbpp