在看think python 第三章 函式章節時，有個練習是：寫乙個四行四列的小網格繪製的程式。
官方例程為：
上面例程中的**為：
"""this module contains a code example related to
think python, 2nd edition
by allen downey
license:
"""from __future__ import print_function, division
# here is a mostly-straightforward solution to the
# two-by-two version of the grid.
defdo_twice
(f):
f() f(
)def
do_four
(f):
do_twice(f)
do_twice(f)
defprint_beam()
:print
('+ - - - -'
, end=
' ')
defprint_post()
:print
('| '
, end=
' ')
defprint_beams()
: do_twice(print_beam)
print
('+'
)def
print_posts()
: do_twice(print_post)
print
('|'
)def
print_row()
: print_beams(
) do_four(print_posts)
defprint_grid()
: do_twice(print_row)
print_beams(
)print_grid(
)# here is a less-straightforward solution to the
# four-by-four grid
defone_four_one
(f, g, h)
: f(
) do_four(g)
h()def
print_plus()
:print
('+'
, end=
' ')
defprint_dash()
:print
('-'
, end=
' ')
defprint_bar()
:print
('|'
, end=
' ')
defprint_space()
:print
(' '
, end=
' ')
defprint_end()
:print()
defnothing()
:"do nothing"
defprint1beam()
: one_four_one(nothing, print_dash, print_plus)
defprint1post()
: one_four_one(nothing, print_space, print_bar)
defprint4beams()
: one_four_one(print_plus, print1beam, print_end)
defprint4posts()
: one_four_one(print_bar, print1post, print_end)
defprint_row()
: one_four_one(nothing, print4posts, print4beams)
defprint_grid()
: one_four_one(print4beams, print_row, nothing)
print_grid(
)comment =
"""after writing a draft of the 4x4 grid, i noticed that many of the
functions had the same structure: they would do something, do
something else four times, and then do something else once.
so i wrote one_four_one, which takes three functions as arguments; it
calls the first one once, then uses do_four to call the second one
four times, then calls the third.
then i rewrote print1beam, print1post, print4beams, print4posts,
print_row and print_grid using one_four_one.
programming is an exploratory process. writing a draft of a program
often gives you insight into the problem, which might lead you to
rewrite the code to reflect the structure of the solution.
--- allen
"""print
(comment)
from __future__ import print_function, division
defprint_beam()
:print
('+ - - - -'
, end=
' ')
defprint_add()
:print
("+"
)def
print_post()
:print
('| '
, end=
' ')
defprint_line()
:print
("|"
)def
do_sometime
(f, n)
:for i in
range(0
, n)
: f(
)def
print_grid
(n):
for i in
range(0
, n)
: do_sometime(print_beam, n)
print_add(
)for j in
range(0
,4):
do_sometime(print_post, n)
print_line()
do_sometime(print_beam, n)
print_add(
)print_grid(2)
print_grid(
4)
+--
--+-
---+
||||
||||
||||
+---
-+--
--+|
||||
||||
|||+
----
+---
-++-
---+
----
+---
-+--
--+|
||||
||||
||||
||||
|||+
----
+---
-+--
--+-
---+
||||
||||
||||
||||
||||
+---
-+--
--+-
---+
----
+|||
||||
||||
||||
||||
|+--
--+-
---+
----
+---
-+||
||||
||||
||||
||||
||+-
---+
----
+---
-+--
--+
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