3.9. ADR Dragon Position Change

  • Move dragon left by 10 and down by 20

  • Move dragon left by 10 and right by 15

  • Move dragon right by 15 and up by 5

  • Move dragon down by 5

3.9.1. Option 1

>>> # left by 10 and down by 20
>>> dragon.position_x -= 10
>>> dragon.position_y += 20
>>>
>>> # left by 10 and right by 15
>>> dragon.position_x += 5
>>>
>>> # right by 15 and up by 5
>>> dragon.position_x += 15
>>> dragon.position_y -= 5
>>>
>>> # down by 5
>>> dragon.position_y += 5

Pros and Cons:

  • Good: extensible to 3D, just add z attribute

  • Bad: require knowledge of an API

  • Bad: the user must know the internals, how to calculate the position, which way is up or down (positive or negative shifting), note that y=-20 means go up by 20 (we have inverted y axis)

  • Bad: violates abstraction (OOP Principle)

  • Bad: violates encapsulation (OOP Principle)

  • Bad: violates Tell, Don't Ask (OOP Principle)

  • Decision: rejected

Consequences:

>>> current_x = dragon.position_x
>>> current_y = dragon.position_y
>>> dragon.set_position(x=current_x-10, y=current_y+20)
>>> new_x = dragon.position_x - 10
>>> new_y = dragon.position_y + 20
>>> dragon.set_position(x=new_x, y=new_y)
>>> sms.send('Hello \U0001F610')

3.9.2. Option 2

>>> dragon.move(-10, 20)  # left by 10 and down by 20
>>> dragon.move(5, 0)     # left by 10 and right by 15
>>> dragon.move(15, -5)   # right by 15 and up by 5
>>> dragon.move(0, 5)     # down by 5

Pros and Cons:

  • Good: move by relative offset

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: require knowledge of an API

  • Bad: not extensible to 3D

  • Bad: the user must know the internals, how to calculate the position, which way is up or down (positive or negative shifting), note that y=-20 means go up by 20 (we have inverted y axis)

  • Bad: violates abstraction (OOP Principle)

  • Bad: violates Tell, Don't Ask (OOP Principle)

  • Decision: rejected

Consequences:

>>> dragon.move(10, -20)  # 2D
>>> dragon.move(10, -20, 30)  # 3D

Use Case:

>>> color = Color(10, 20, 30)
>>> color = Color(10, 20, 30, 0.5)
>>> run('ls', True, False)  # bad
>>> read_csv('iris.csv', ';', 'utf-8', True)  # bad
p { margin: 25px; }
p { margin: 25px 50px; }
p { margin: 25px 50px 75px; }
p { margin: 25px 50px 75px 100px; }

3.9.3. Option 3

>>> dragon.move((-10, 20))  # left by 10 and down by 20
>>> dragon.move((5, 0))     # left by 10 and right by 15
>>> dragon.move((15, -5))   # right by 15 and up by 5
>>> dragon.move((0, 5))     # down by 5

Pros and Cons:

  • Bad: require knowledge of an API

  • Bad: Move by setting absolute position

  • Bad: controller must know other variables, such as speed factor (snail is slower than a dragon), surface on which the dragon is moving (solid is faster than water or ice), injuries (if dragon is not injured with his for example left foot)

  • Bad: the user must know the internals, how to calculate the position, which way is up or down (positive or negative shifting), note that y=-20 means go up by 20 (we have inverted y axis)

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: not extensible to 3D

  • Bad: violates abstraction (OOP Principle)

  • Bad: violates Tell, Don't Ask (OOP Principle)

  • Decision: rejected

Consequences:

>>> dragon.move((10, -20))
>>> dragon.move((10, -20, 30))

Use Case:

>>> run(('ls', True, False, None))

3.9.4. Option 4

>>> dragon.move([
...     (-10, 20),  # left by 10 and down by 20
...     (5, 0),     # left by 10 and right by 15
...     (15, -5),   # right by 15 and up by 5
...     (0, 5),     # down by 5
... ])

Pros and Cons:

  • Good: extensible to 3D

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: require knowledge of an API

  • Bad: Move by setting absolute position

  • Bad: controller must know other variables, such as speed factor (snail is slower than a dragon), surface on which the dragon is moving (solid is faster than water or ice), injuries (if dragon is not injured with his for example left foot)

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: the user must know the internals, how to calculate the position, which way is up or down (positive or negative shifting), note that y=-20 means go up by 20 (we have inverted y axis)

  • Bad: violates abstraction (OOP Principle)

  • Bad: violates Tell, Don't Ask (OOP Principle)

  • Decision: rejected

Consequences:

>>> dragon.move([
...     (-10, 20),
...     (5, 0, -5),
...     (0, 10, 20),
...     (0, -5),
... ])

3.9.5. Option 5

>>> dragon.move(0, 0, 20, 10)    # left by 10 and down by 20
>>> dragon.move(0, 15, 0, 10)    # left by 10 and right by 15
>>> dragon.move(5, 15, 0, 0)     # right by 15 and up by 5
>>> dragon.move(0, 0, 5, 0)      # down by 5
>>> dragon.move((0, 0, 20, 10))  # left by 10 and down by 20
>>> dragon.move((0, 15, 0, 10))  # left by 10 and right by 15
>>> dragon.move((5, 15, 0, 0))   # right by 15 and up by 5
>>> dragon.move((0, 0, 5, 0))    # down by 5
>>> dragon.move([
...     (0, 0, 20, 10)),        # left by 10 and down by 20
...     (0, 15, 0, 10)),        # left by 10 and right by 15
...     (5, 15, 0, 0)),         # right by 15 and up by 5
...     (0, 0, 5, 0)),          # down by 5
... ]

Pros and Cons:

  • Good: there is only one method move() responsible for moving

  • Bad: Python has keyword arguments, so use it

  • Bad: require knowledge of an API

  • Bad: not extensible to 3D

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: the user must know the internals, how to calculate the position, which way is up or down (positive or negative shifting), note that y=-20 means go up by 20 (we have inverted y axis)

  • Bad: violates abstraction (OOP Principle)

  • Decision: rejected

Consequences:

>>> dragon.move(0, 10, 0, 20)  # bad
>>> dragon.move(0, 10, 0, 20, 0, 30)  # bad
>>> dragon.move([
...     (0, 10, 0, 20),
...     (0, 10, 0, 20, 0, 30),
...     (0, 10, 0, 20),
...     (0, 10, 0, 20, 0, 30),
... ])

Use Case:

>>> run(True, False, None)  
Code 3.100. CSS: top, right, bottom, left
p {
    margin: 25px 50px 75px 100px;
}

3.9.6. Option 6

>>> dragon.move_xy(-10, 20)  # left by 10 and down by 20
>>> dragon.move_xy(5, 0)     # left by 10 and right by 15
>>> dragon.move_xy(15, -5)   # right by 15 and up by 5
>>> dragon.move_xy(0, 5)     # down by 5

Pros and Cons:

  • Bad: Move by setting absolute position

  • Bad: controller must know other variables, such as speed factor (snail is slower than a dragon), surface on which the dragon is moving (solid is faster than water or ice), injuries (if dragon is not injured with his for example left foot)

  • Bad: the user must know the internals, how to calculate the position, which way is up or down (positive or negative shifting), note that y=-20 means go up by 20 (we have inverted y axis)

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: name indicates that this is not extensible to 3D

  • Bad: violates abstraction (OOP Principle)

  • Bad: violates Tell, Don't Ask (OOP Principle)

  • Decision: rejected

Consequences:

>>> dragon.move_xy(10, -20)  # 2D
>>> dragon.move_xyz(10, -20, 0)  # 3D

3.9.7. Option 7

>>> # left by 10 and down by 20
>>> dragon.move_x(10)
>>> dragon.move_y(-20)
>>>
>>> # left by 10 and right by 15
>>> dragon.move_x(5)
>>>
>>> # right by 15 and up by 5
>>> dragon.move_x(15)
>>> dragon.move_y(-5)
>>>
>>> # down by 5
>>> dragon.move_y(5)

Pros and Cons:

  • Good: extensible to 3D, just add another method

  • Bad: require knowledge of an API

  • Bad: Move by setting absolute position

  • Bad: controller must know other variables, such as speed factor (snail is slower than a dragon), surface on which the dragon is moving (solid is faster than water or ice), injuries (if dragon is not injured with his for example left foot)

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: the user must know the internals, how to calculate the position, which way is up or down (positive or negative shifting), note that y=-20 means go up by 20 (we have inverted y axis)

  • Bad: violates abstraction (OOP Principle)

  • Bad: violates Tell, Don't Ask (OOP Principle)

  • Decision: rejected

Consequences:

>>> dragon.move_x(10)  # ok
>>> dragon.move_y(-20)  # ok
>>> dragon.move_z(0)  # ok

3.9.8. Option 8

>>> # left by 10 and down by 20
>>> dragon.move_horizontal(10)
>>> dragon.move_vertical(-20)
>>>
>>> # left by 10 and right by 15
>>> dragon.move_horizontal(5)
>>>
>>> # right by 15 and up by 5
>>> dragon.move_horizontal(15)
>>> dragon.move_vertical(-5)
>>>
>>> # down by 5
>>> dragon.move_vertical(5)

Pros and Cons:

  • Good: extensible to 3D, just add another method

  • Bad: require knowledge of an API

  • Bad: Move by setting absolute position

  • Bad: controller must know other variables, such as speed factor (snail is slower than a dragon), surface on which the dragon is moving (solid is faster than water or ice), injuries (if dragon is not injured with his for example left foot)

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: the user must know the internals, how to calculate the position, which way is up or down (positive or negative shifting), note that y=-20 means go up by 20 (we have inverted y axis)

  • Bad: violates abstraction (OOP Principle)

  • Bad: violates Tell, Don't Ask (OOP Principle)

  • Decision: rejected

Consequences:

>>> dragon.move_horizontal(10)  # ok
>>> dragon.move_vertical(-20)  # ok
>>> dragon.move_depth(0)  # bad, depth or altitude?
>>> dragon.move_altitude(0)  # bad, depth or altitude?

3.9.9. Option 9

>>> # left by 10 and down by 20
>>> dragon.move_left(10)
>>> dragon.move_down(20)
>>>
>>> # left by 10 and right by 15
>>> dragon.move_left(10)
>>> dragon.move_right(15)
>>>
>>> # right by 15 and up by 5
>>> dragon.move_right(15)
>>> dragon.move_up(5)
>>>
>>> # down by 5
>>> dragon.move_down(5)

Pros and Cons:

  • Bad: not extensible

  • Bad: to complex for now

  • Bad: not possible to do movement in opposite directions in the same time

  • Decision: rejected, complex

Consequences:

>>> dragon.move_upright(10)
>>> dragon.move_upleft(10)
>>> dragon.move_downright(10)
>>> dragon.move_downleft(10)
>>> dragon.move_up_right(10)
>>> dragon.move_up_left(10)
>>> dragon.move_down_right(10)
>>> dragon.move_down_left(10)

Use Case:

>>> db.execute_select(SQL)
>>> db.execute_select_where(SQL)
>>> db.execute_select_order(SQL)
>>> db.execute_select_limit(SQL)
>>> db.execute_select_offset(SQL)
>>> db.execute_select_order_limit(SQL)
>>> db.execute_select_where_order_limit(SQL)
>>> db.execute_select_where_order_limit_offset(SQL)
>>> db.execute_insert(SQL)
>>> db.execute_insert_values(SQL)
>>> db.execute_alter(SQL)
>>> db.execute_alter_table(SQL)
>>> db.execute_alter_index(SQL)
>>> db.execute_create(SQL)
>>> db.execute_create_table(SQL)
>>> db.execute_create_index(SQL)
>>> db.execute_create_database(SQL)
>>>
>>> db.execute(SQL)
>>> read_csv_with_encoding('iris.csv', 'utf-8')
>>> read_csv_with_delimiter('iris.csv', ';')
>>> read_csv_with_delimiter_encoding('iris.csv', ';', 'utf-8')
>>> read_csv_with_delimiter_encoding_verbose('iris.csv', ';', 'utf-8', True)
>>> match get_key_pressed():
...     case Key.ARROW_LEFT: dragon.move_left()
...     case Key.ARROW_RIGHT: dragon.move_right()
...     case Key.ARROW_UP: dragon.move_up()
...     case Key.ARROW_DOWN: dragon.move_down()

3.9.10. Option 10

>>> dragon.move(x=-10, y=20)    # left by 10 and down by 20
>>> dragon.move(x=5, y=0)       # left by 10 and right by 15
>>> dragon.move(x=15, y=-5)     # right by 15 and up by 5
>>> dragon.move(x=0, y=5)       # down by 5
>>> dragon.move(dx=-10, dy=20)  # left by 10 and down by 20
>>> dragon.move(dx=5, dy=0)     # left by 10 and right by 15
>>> dragon.move(dx=15, dy=-5)   # right by 15 and up by 5
>>> dragon.move(dx=0, dy=5)     # down by 5
>>> dragon.move(horizontal=-10, vertical=20)  # left by 10 and down by 20
>>> dragon.move(horizontal=5, vertical=0)     # left by 10 and right by 15
>>> dragon.move(horizontal=15, vertical=-5)   # right by 15 and up by 5
>>> dragon.move(horizontal=0, vertical=5)     # down by 5

Pros and Cons:

  • Good: extensible to 3D

  • Good: move by relative shifting (left, right, up, down)

  • Good: encapsulation, object knows current position, state and does the move

  • Good: easy .move()

  • Bad: you have to know, which axis is left and with is right

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: the user must know the internals, how to calculate the position, which way is up or down (positive or negative shifting), note that y=-20 means go up by 20 (we have inverted y axis)

  • Bad: controller must know other variables, such as speed factor (snail is slower than a dragon), surface on which the dragon is moving (solid is faster than water or ice), injuries (if dragon is not injured with his for example left foot)

  • Bad: you cannot prevent negative shifting (i.e.: x=-10)

  • Bad: violates abstraction (OOP Principle)

  • Bad: violates Tell, Don't Ask (OOP Principle)

  • Decision: rejected, it requires to much inside knowledge of API from user

Consequences:

>>> dragon.move(x=10, y=-20)  # 2D, ok
>>> dragon.move(x=10, y=-20, z=30)  # 3D, ok
>>> dragon.move(dx=10, dy=-20)  # 2D, ok
>>> dragon.move(dx=10, dy=-20, dz=30)  # 3D, ok
>>> dragon.move(horizontal=10, vertical=-20)  # 2D, ok
>>> dragon.move(horizontal=10, vertical=-20, depth=30)  # 3D, bad, depth or altitude
>>> dragon.move(horizontal=10, vertical=-20, altitude=30)  # 3D, bad, depth or altitude

3.9.11. Option 11

>>> dragon.move(left=10, down=20)    # left by 10 and down by 20
>>> dragon.move(left=10, right=15)   # left by 10 and right by 15
>>> dragon.move(right=15, up=5)      # right by 15 and up by 5
>>> dragon.move(down=5)              # down by 5

Pros and Cons:

  • Good: extensible to 3D

  • Good: move by relative shifting (left, right, up, down)

  • Good: encapsulation, object knows current position, state and does the move

  • Good: hides business logic (inverted y-axis)

  • Good: easy .move()

  • Good: you can prevent negative shifting (i.e.: left=-10)

  • Good: encapsulation, object knows current position and moves

  • Decision: candidate

Consequences:

>>> dragon.move(right=15, up=5)
>>> dragon.move(right=15, up=5, depth=10)
>>> dragon.move(right=15, up=5, altitude=10)

Use Case:

>>> read_csv('iris.csv', ';', 'utf-8', True)
>>> read_csv('iris.csv', delimiter=';', encoding='utf-8', verbose=True)
>>> user.login_username('mwatney')
>>> user.login_password('Ares3')
>>> user.login(username='mwatney', password='Ares3')
Code 3.101. CSS: self explanatory
p {
    margin-top: 25px;
    margin-right: 50px;
    margin-bottom: 75px;
    margin-left: 100px;
}

3.9.12. Option 12

>>> dragon.shift(left=10, down=20)    # left by 10 and down by 20
>>> dragon.shift(left=10, right=15)   # left by 10 and right by 15
>>> dragon.shift(right=15, up=5)      # right by 15 and up by 5
>>> dragon.shift(down=5)              # down by 5
>>> dragon.fly(left=10, down=20)    # left by 10 and down by 20
>>> dragon.fly(left=10, right=15)   # left by 10 and right by 15
>>> dragon.fly(right=15, up=5)      # right by 15 and up by 5
>>> dragon.fly(down=5)              # down by 5

Pros and Cons:

  • Good: extensible to 3D

  • Good: move by relative shifting (left, right, up, down)

  • Good: encapsulation, object knows current position, state and does the move

  • Bad: method names are too use-case specific

  • Decision: rejected, method names too use-case specific

Consequences:

>>> dragon.fly(left=10, down=20)     # does the same, but different name
>>> hero.walk(left=10, down=20)      # does the same, but different name
>>> snake.slide(left=10, down=20)    # does the same, but different name

Use Case:

>>> locmem.store(key='...', value='..')
>>> database.insert(column='...', value='...')
>>> filesystem.write(filename='...', content='...')
>>> locmem.retrieve(key='...')
>>> database.select(column='...')
>>> filesystem.read(filename='...')

3.9.13. Option 13

>>> dragon.change_position(left=10, down=20)    # left by 10 and down by 20
>>> dragon.change_position(left=10, right=15)   # left by 10 and right by 15
>>> dragon.change_position(right=15, up=5)      # right by 15 and up by 5
>>> dragon.change_position(down=5)              # down by 5
>>> dragon.position_change(left=10, down=20)    # left by 10 and down by 20
>>> dragon.position_change(left=10, right=15)   # left by 10 and right by 15
>>> dragon.position_change(right=15, up=5)      # right by 15 and up by 5
>>> dragon.position_change(down=5)              # down by 5
>>> dragon.mod_position(left=10, down=20)    # left by 10 and down by 20
>>> dragon.mod_position(left=10, right=15)   # left by 10 and right by 15
>>> dragon.mod_position(right=15, up=5)      # right by 15 and up by 5
>>> dragon.mod_position(down=5)              # down by 5

Pros and Cons:

  • Good: extensible to 3D

  • Good: move by relative shifting (left, right, up, down)

  • Good: encapsulation, object knows current position and moves

  • Good: mod_position() is compatible with get_position() and set_position()

  • Bad: the method names are a bit too complex for

  • Decision: candidate

Use Case:

>>> locmem.set(key='...', value='..')
>>> database.set(key='...', value='..')
>>> filesystem.set(key='...', value='..')
>>> locmem.get(key='...')
>>> database.get(key='...')
>>> filesystem.get(key='...')

3.9.14. Option 14

  • Move by setting absolute position along path

>>> dragon.move_to(10, -20)
>>> dragon.move_to(50, -100)
>>> dragon.move_to(5, 0)
>>> dragon.move_to((10, -20))
>>> dragon.move_to((50, -100))
>>> dragon.move_to((5, 0))
>>> dragon.move_to([
...     (10, -20),
...     (50, -100),
...     (5, 0),
... ])

Pros and Cons:

  • Bad: move by setting absolute position

  • Bad: similar to .set_position()

  • Bad: require knowledge of an API

  • Bad: not extensible to 3D

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: the user must know the internals, how to calculate the position, which way is up or down (positive or negative shifting), note that y=-20 means go up by 20 (we have inverted y axis)

  • Bad: controller must know other variables, such as speed factor (snail is slower than a dragon), surface on which the dragon is moving (solid is faster than water or ice), injuries (if dragon is not injured with his for example left foot)

  • Bad: violates abstraction (OOP Principle)

  • Bad: violates Tell, Don't Ask (OOP Principle)

  • Decision: rejected, violates Model-View-Controller (MVC)

Rationale:

  • move() make an animation of movement (step by step)

  • set_position() movement instantly (instant set)

Example:

>>> dragon.move_to([
...     (10, -20),
...     (50, -100),
...     (5),
... ])
>>> dragon.move_to([
...     (10, -20, 0),
...     (50, -100, 0),
...     (5, 0, 0),
... ])

3.9.15. Option 15

  • Move by setting absolute position along path

>>> dragon.move_to({'x':-10, 'y':20})
>>> dragon.move_to({'x':10, 'y':-100})
>>> dragon.move_to({'x':50, 'y':-100})
>>> dragon.move_to([
...     {'x':10, 'y':-20},
...     {'x':10, 'y':-15},
... ])

Pros and Cons:

  • Bad: require knowledge of an API

  • Bad: not extensible to 3D

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: the user must know the internals, how to calculate the position, which way is up or down (positive or negative shifting), note that y=-20 means go up by 20 (we have inverted y axis)

  • Bad: violates abstraction (OOP Principle)

  • Bad: violates Tell, Don't Ask (OOP Principle)

  • Decision: rejected

3.9.16. Option 16

>>> dragon.move([
...     Point(x=10, y=20),
...     Point(x=10, y=15),
...     Point(x=10, y=15),
... ])

Pros and Cons:

  • Good: Move by setting absolute position on a path

  • Good: This is how they do it in games

  • Good: extensible to 3D

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: require knowledge of an API

  • Decision: possible, common practice in game-dev

Example:

>>> path = [
...     Point(x=10, y=20),
...     Point(x=10, y=15),
...     Point(x=10, y=15),
... ]
>>>
>>> dragon.move(path)

Use Case:

>>> path = calculate_path(from_point, to_point)
>>> dragon.move(path)
>>> request.get('https://python3.info', traceroute=[
...     '10.13.37.1',
...     '212.77.100.101',
...     '162.13.37.1',
... ])

3.9.17. Option 17

  • Move by relative shifting in axis

>>> dragon.move({'dx': 10, 'dy': 20})
>>> dragon.move({'dx': 10, 'dy': 20})
>>> dragon.move({'dx': 10, 'dy': 20})
>>> dragon.move([
...     {'dx': -10, 'dy': 20},
...     {'dx': -10, 'dy': 0}])

Pros and Cons:

  • Bad: require knowledge of an API

  • Bad: not extensible to 3D

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: the user must know the internals, how to calculate the position, which way is up or down (positive or negative shifting), note that dy=-20 means go up by 20 (we have inverted y axis)

  • Bad: violates abstraction (OOP Principle)

  • Bad: violates Tell, Don't Ask (OOP Principle)

  • Decision: rejected

3.9.18. Option 18

  • Move by relative shifting to the sides

>>> dragon.move({'left':50, 'down':100})
>>> dragon.move({'left':50, 'down':100})
>>> dragon.move({'left':50, 'down':100})
>>> dragon.move([
...     {'left':50, 'down':100},
...     {'left':50, 'right':100},
...     {'down':50}])

Pros and Cons:

  • Bad: require knowledge of an API

  • Bad: not extensible to 3D

  • Bad: requires knowledge of business logic (inverted y-axis)

  • Bad: violates abstraction (OOP Principle)

  • Bad: **kwargs can convert to keyword arguments

  • Decision: rejected

3.9.19. Option 19

  • Move by relative shifting to the sides

>>> dragon.move({'direction': 'left', 'distance': 20})
>>> dragon.move({'direction': 'left', 'distance': 10})
>>> dragon.move({'direction': 'right', 'distance': 20})
>>> dragon.move([
...     {'direction': 'left', 'distance': 20},
...     {'direction': 'left', 'distance': 10},
...     {'direction': 'right', 'distance': 20}])

Pros and Cons:

  • Good: extensible to 3D

  • Bad: require knowledge of an API

  • Decision: rejected

3.9.20. Option 20

  • Move by relative shifting to the sides

>>> dragon.move(Direction('left', distance=20))
>>> dragon.move(Direction('left', distance=10))
>>> dragon.move(Direction('right', distance=20))
>>> dragon.move([
...     Direction('left', distance=20),
...     Direction('left', distance=10),
...     Direction('right', distance=20),
... ])

Pros and Cons:

  • Good: extensible to 3D

  • Bad: require knowledge of an API

  • Bad: additional entities

  • Decision: rejected

3.9.21. Option 21

  • Move by relative shifting to the sides

>>> dragon.move('left', 20)
>>> dragon.move('right', 5)
>>> dragon.move('left', distance=20)
>>> dragon.move('right', distance=5)
>>> dragon.move(direction='left', distance=20)
>>> dragon.move(direction='right', distance=5)

Pros and Cons:

  • Good: extensible

  • Good: extensible to 3D

  • Bad: not possible to do movement in opposite directions in the same time

  • Decision: rejected

Consequences:

>>> dragon.move('l', 20)
>>> dragon.move('r', 5)
>>> dragon.move('l', distance=20)
>>> dragon.move('r', distance=5)
>>> dragon.move(direction='l', distance=20)
>>> dragon.move(direction='r', distance=5)

Use Case:

>>> plt.plot(x, y, color='r')  # red
>>> plt.plot(x, y, color='b')  # blue
>>> plt.plot(x, y, color='g')  # green
>>> plt.plot(x, y, color='k')  # what color is that?
>>> df.plot(kind='line')
>>> df.interpolate('polynomial')
>>> plt.plot(x, y, color='red')

3.9.22. Option 22

  • Move by relative shifting to the sides

>>> dragon.move(Left(20))
>>> dragon.move(Left(10))
>>> dragon.move(Right(20))
>>> dragon.move([
...     Left(20),
...     Left(10),
...     Right(20),
... ])

Pros and Cons:

  • Good: extensible to 3D

  • Bad: require knowledge of an API

  • Bad: additional entities

  • Decision: rejected

3.9.23. Option 23

  • Move by relative shifting to the sides

  • Bind to keyboard key codes

>>> # keyboard key codes
>>> LEFT = 0x61
>>> DOWN = 0x62
>>> RIGHT = 0x63
>>> UP = 0x64
>>>
>>> # movement
>>> dragon.move(LEFT, 20)
>>> dragon.move(LEFT, distance=20)
>>> dragon.move(direction=LEFT, distance=20)
>>> # keyboard key codes
>>> DIRECTION_LEFT = 0x61
>>> DIRECTION_DOWN = 0x62
>>> DIRECTION_UP = 0x64
>>> DIRECTION_RIGHT = 0x63
>>>
>>> # movement
>>> dragon.move(DIRECTION_LEFT, 20)
>>> dragon.move(DIRECTION_LEFT, distance=20)
>>> dragon.move(direction=DIRECTION_LEFT, distance=20)
>>> # keyboard key codes
>>> class Direction(IntEnum):
...     LEFT = 0x61
...     DOWN = 0x62
...     RIGHT = 0x63
...     UP = 0x64
>>>
>>>
>>> # movement
>>> dragon.move(Direction.LEFT, 5)
>>> dragon.move(Direction.LEFT, distance=5)
>>> dragon.move(direction=Direction.LEFT, distance=5)

Pros and Cons:

  • Good: explicit

  • Good: verbose

  • Good: extensible

  • Bad: to chaotic

  • Bad: to complex for now

  • Bad: there is no easy way to know which are possible directions

  • Bad: not possible to do movement in opposite directions in the same time

  • Decision: rejected, complex

../../_images/keyboard-keycodes-us.png

3.9.24. Option 24

  • Move by relative shifting to the sides

  • Bind to keyboard key codes

>>> # keyboard key codes
>>> ARROW_LEFT = 0x61
>>> ARROW_DOWN = 0x62
>>> ARROW_RIGHT = 0x63
>>> ARROW_UP = 0x64
>>>
>>>
>>> def move(key, time):
...     if key == ARROW_LEFT:
...         dragon.move_left(time)
...     elif key == ARROW_DOWN:
...         dragon.move_down(time)
...     elif key == ARROW_RIGHT:
...         dragon.move_right(time)
...     elif key == ARROW_UP:
...         dragon.move_up(time)
>>>
>>>
>>> move(ARROW_UP, 5)
>>> # keyboard key codes
>>> class Key(IntEnum):
...     ARROW_LEFT = 0x61
...     ARROW_DOWN = 0x62
...     ARROW_RIGHT = 0x63
...     ARROW_UP = 0x64
>>>
>>>
>>> def move(key, time):
...     match key:
...         case Key.ARROW_LEFT: dragon.move_left(time)
...         case Key.ARROW_DOWN: dragon.move_down(time)
...         case Key.ARROW_RIGHT: dragon.move_right(time)
...         case Key.ARROW_UP: dragon.move_up(time)
...         case _: raise NotImplementedError
>>>
>>>
>>> move(Key.ARROW_UP, 5)

Pros and Cons:

  • Good: explicit

  • Good: verbose

  • Good: extensible

  • Good: there is a enumeration of possible choices for directions

  • Bad: to complex for now

  • Decision: rejected, complex

3.9.25. Option 25

>>> # keyboard key codes
>>> class Key(IntEnum):
...     ARROW_LEFT = 0x61
...     ARROW_DOWN = 0x62
...     ARROW_RIGHT = 0x63
...     ARROW_UP = 0x64
>>>
>>>
>>> game = GameEngine()
>>> game.bind(Key.ARROW_LEFT, dragon.move_left)     # good
>>> game.bind(Key.ARROW_DOWN, dragon.move_down)     # good
>>> game.bind(Key.ARROW_RIGHT, dragon.move_right)   # good
>>> game.bind(Key.ARROW_UP, dragon.move_up)         # good
>>> game.run()

Pros and Cons:

  • Bad: not extensible

  • Bad: to complex for now

  • Bad: not possible to do movement in opposite directions in the same time

  • Decision: rejected, complex

3.9.26. Decision

>>> dragon.change_position(left=10, down=20)

Pros and Cons:

  • Good: consistent with set_position() and get_position()

  • Good: verbose

  • Good: extensible

Implementation:

>>> class Dragon:
...     def change_position(self, *,
...                         left: int = 0, right: int = 0,
...                         down: int = 0, up: int = 0,
...                         ) -> None: ...