在Python中实现替换字符串中的子串的示例

> "This is a %(var)s" % {"var":"dog"}
'This is a dog'
>

> from string import Template
> words = Template("This is $var")
> print(words.substitute({"var": "dog"})) # 通过字典的方式来传参
This is dog
> print(words.substitute(var="dog"))   # 通过关键字方式来传参
This is dog
>

> from string import Template
> letter = """Dear $customer,
... I hope you are having a great time!
... If you do not find Room $room to your satisfaction, let us know.
... Please accept this $$5 coupon.
...     Sincerely,
...     $manager,
...     ${name}Inn"""
> template = Template(letter)
> letter_dict = {"name": "Sleepy", "customer": "Fred Smith", "manager": "Tom Smith", "room": 308}
> print(template.substitute(letter_dict))
Dear Fred Smith,
I hope you are having a great time!
If you do not find Room 308 to your satisfaction, let us know.
Please accept this $5 coupon.
    Sincerely,
    Tom Smith,
    SleepyInn
>

> locals()   # 刚进入时，没有其他变量
{'__builtins__': <module '__builtin__' (built-in)>, '__name__': '__main__', '__doc__': None, '__package__': None}
> name = "Alice" # 创建本地变量name 
> age = 18   # 创建本地变量age
> locals()   # 再执行locals()函数就可以看到name, age的键值队
{'name': 'Alice', '__builtins__': <module '__builtin__' (built-in)>, 'age': 18, '__package__': None, '__name__': '__mai
__', '__doc__': None}
> locals()["name"] # 通过键name来获取值
'Alice'
> locals()["age"] # 通过键age来获取值
18
>

> from string import Template
> msg = Template("The square of $number is $square")
> for number in range(10):
...  square = number * number
...  print msg.substitute(locals())
...
The square of 0 is 0
The square of 1 is 1
The square of 2 is 4
The square of 3 is 9

> from string import Template
> msg = Template("The square of $number is $square")
> for i in range(4):
...  print msg.substitute(number=i, square=i*i)
...
The square of 0 is 0
The square of 1 is 1
The square of 2 is 4
The square of 3 is 9
>

> from string import Template
> msg = Template("The square of $number is $square")
> for number in range(4):
...  print msg.substitute(locals(), square=number*number)
...
The square of 0 is 0
The square of 1 is 1
The square of 2 is 4
The square of 3 is 9
>

> from string import Template
> msg = Template("It is $adj $msg")
> adj = "interesting"
> print(msg.substitute(locals(), msg="message"))
It is interesting message