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Commit67d0f49

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Tweaks to types page
1 parent078fc59 commit67d0f49

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‎backend/main/chapters/c11_tic_tac_toe_project.py‎

Lines changed: 42 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,15 @@
11
# flake8: NOQA E501
22
importast
3+
fromrandomimportchoice,randint
34
fromstringimportascii_uppercase
45
fromtypingimportList
5-
fromrandomimportchoice,randint
66

7-
frommain.textimportExerciseStep,Page,MessageStep,Disallowed,VerbatimStep,Step
7+
frommain.textimportExerciseStep,Page,MessageStep,Disallowed,VerbatimStep
88

99

1010
defgenerate_board(board_type):
1111
winning=choice([True,False])
12-
size=randint(3,10)
12+
size=randint(3,9)
1313
char1=choice(ascii_uppercase)
1414
char2=choice(ascii_uppercase)
1515
chars= [char1,char2,' ']
@@ -907,13 +907,13 @@ def generate_inputs(cls):
907907
You are already about halfway done with the project. Keep going!
908908
"""
909909

910-
classTypes(Page):
911910

911+
classTypes(Page):
912912
classfive_different_types(VerbatimStep):
913913
"""
914-
So far we have been working withvarious kinds of data: strings, lists, numbers and most recently booleans.
915-
Python will recognize and treat different values such as `'Hello World'` and `23` differently.
916-
We cansee how Python recognizes these values. There is a command`type`that reveals it:
914+
So far we've seenvarious kinds of data: strings, lists, numbers and booleans.
915+
These are called *types*. Every value has a type which affects how it behaves
916+
and canbe revealed with the`type`function:
917917
918918
__copyable__
919919
__program_indented__
@@ -929,17 +929,19 @@ def program(self):
929929
classcheck_type_manually(VerbatimStep):
930930
"""
931931
Python reports first that `type('Hello World')` is `<class 'str'>`. Don't worry about `class` for now.
932-
Python is telling us that the type of a string is`str`, which is short for *string*.
932+
`str` is short for *string*.
933933
934-
Then `True` is `bool` (short for *boolean*) and `[1, 2, 3]` has type `list`.
934+
Then `True` isa`bool` (short for *boolean*) and `[1, 2, 3]` has type `list`.
935935
936936
Note that there are two types for numbers:
937937
938938
- `int`, short for 'integer', is for whole numbers, meaning no fractions or decimal points.
939939
- `float`, short for 'floating point number', is for numbers with a decimal point and maybe a fractional part
940940
941-
In most cases you don't have to worry about the difference, as you can mix the two when doing maths.
942-
Let us verify one of these in the shell:
941+
In most cases you don't have to worry about the different types of number, as you can mix the two when doing maths.
942+
943+
Types are values which can be used in various ways, just like other values.
944+
For example, try this in the shell:
943945
944946
__program_indented__
945947
"""
@@ -950,8 +952,10 @@ class check_type_manually(VerbatimStep):
950952

951953
classdifferent_types_look_same(VerbatimStep):
952954
"""
953-
Sometimes different types can look the same when printed, even though they are different when evaluated:
955+
Values with different types are usually quite different from each other, but they can look the same when printed,
956+
which can be confusing. Try this:
954957
958+
__copyable__
955959
__program_indented__
956960
957961
(You can use `print(repr(123))` and `print(repr('123'))` to tell the difference. What's `repr`? Google it!)
@@ -964,9 +968,12 @@ def program(self):
964968

965969
classplus_has_two_meanings(VerbatimStep):
966970
"""
967-
Operators such as `+` have different meanings for `str` and `int`:
971+
Different types have different methods and support different operators.
972+
The same method or operator can also mean different things.
973+
For example, see how `+` has different meanings for `str` and `int`:
968974
969-
__program_indented__
975+
__copyable__
976+
__program_indented__
970977
"""
971978

972979
predicted_output_choices= [
@@ -988,7 +995,8 @@ class less_than_has_two_meanings(VerbatimStep):
988995
Python automatically figures out the meaning of `+` from the types of the inputs.
989996
Similarly `<` acts differently on two strings and two integers:
990997
991-
__program_indented__
998+
__copyable__
999+
__program_indented__
9921000
"""
9931001

9941002
predicted_output_choices= [
@@ -1004,11 +1012,14 @@ def program(self):
10041012

10051013
classless_than_sorting_strings(VerbatimStep):
10061014
"""
1007-
So `<` acts as the usual"less than" between two integers, because `13` is less than `120`,
1008-
but it acts as the dictionary ordering between two strings: `13` is alphabetically after `120`.
1009-
Let's see this in more detail. `<` is used by default in the list function `sorted`:
1015+
So `<` acts as the usual'less than' between two integers, because `13` is less than `120`,
1016+
but it acts as the dictionary ordering between two strings: `13` is'alphabetically' after `120`
1017+
because `3` comes after `2`.
10101018
1011-
__program_indented__
1019+
See what difference this makes when sorting a list:
1020+
1021+
__copyable__
1022+
__program_indented__
10121023
"""
10131024

10141025
predicted_output_choices= [
@@ -1044,10 +1055,6 @@ def check(self):
10441055

10451056
classfixing_type_errors_with_conversion(ExerciseStep):
10461057
"""
1047-
***Using `+` between a `str` and an `int` is an error!***
1048-
1049-
TypeError: unsupported operand type(s) for +: 'int' and 'str'
1050-
10511058
Using a string instead of an integer in `range` like `range('5')`,
10521059
or in list subscripting like `list['3']` will also lead to an error.
10531060
@@ -1061,7 +1068,7 @@ class fixing_type_errors_with_conversion(ExerciseStep):
10611068
__copyable__
10621069
number = '3'
10631070
for i in range(number):
1064-
print('Starting... ' +(i + 1))
1071+
print('Starting... ' + i + 1)
10651072
print('Go!')
10661073
10671074
The correct program should print:
@@ -1077,7 +1084,9 @@ class fixing_type_errors_with_conversion(ExerciseStep):
10771084

10781085
hints="""
10791086
At what points is this code broken?
1080-
Use the type functions on the broken variables to convert the wrong types to the correct ones!
1087+
There are values that need to be converted to a different type.
1088+
Specifically there's a `str` that needs to be converted to an `int`.
1089+
And an `int` that needs to be converted to a `str`.
10811090
"""
10821091

10831092
tests= [
@@ -1098,6 +1107,8 @@ class fixing_type_errors_with_conversion(ExerciseStep):
10981107
"""),
10991108
]
11001109

1110+
disallowed=Disallowed(ast.JoinedStr,label="f-strings")
1111+
11011112
defsolution(self,number:str):
11021113
foriinrange(int(number)):
11031114
print('Starting... '+str(i+1))
@@ -1184,6 +1195,11 @@ def generate_inputs(cls):
11841195
]
11851196

11861197
final_text="""
1187-
You learned about types in Python and how to avoid common type problems by converting types.
1198+
Excellent!
1199+
1200+
By the way, when you need to concatenate strings and numbers, remember that you can also
1201+
use f-strings. They often look nicer.
1202+
1203+
You've learned about types in Python and how to avoid common errors by converting types.
11881204
Keep going with the rest of the project!
11891205
"""

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