Template 方法

Python 中的正则表达式

Maria Eugenia Inzaugarat

Data Scientist

Template 字符串

语法更简单
比 f-string 慢
受限：不支持格式说明符
适合处理外部格式化的字符串

基础语法

from string import Template

my_string = Template('Data science has been called $identifier')

my_string.substitute(identifier="sexiest job of the 21st century")

'Data science has been called sexiest job of the 21st century'

替换

可使用多个 $identifier
可使用变量

from string import Template
job = "Data science"
name = "sexiest job of the 21st century"

my_string = Template('$title has been called $description')

my_string.substitute(title=job, description=name)

'Data science has been called sexiest job of the 21st century'

替换

当标识符后跟有效字符时，用 ${identifier}

my_string = Template('I find Python very ${noun}ing but my sister has lost $noun')

my_string.substitute(noun="interest")

'I find Python very interesting but my sister has lost interest'

替换

使用 $$ 转义美元符号

my_string = Template('I paid for the Python course only $$ $price, amazing!')

my_string.substitute(price="12.50")

'I paid for the Python course only $ 12.50, amazing!'

替换

缺少占位符时抛出错误

favorite = dict(flavor="chocolate")

my_string = Template('I love $flavor $cake very much')

my_string.substitute(favorite)

Traceback (most recent call last):
KeyError: 'cake'

替换

favorite = dict(flavor="chocolate")
my_string = Template('I love $flavor $cake very much')

try:
    my_string.substitute(favorite) 
except KeyError:
      print("missing information")

missing information

安全替换

始终尝试返回可用字符串
缺失占位符会原样出现在结果中

favorite = dict(flavor="chocolate")
my_string = Template('I love $flavor $cake very much')

my_string.safe_substitute(favorite)

'I love chocolate $cake very much'

应使用哪种？

str.format()：
- 适合入门。概念适用于 f-string。
- 兼容所有 Python 版本。
f-strings：
- 通常优先于其他方法。
- 仅适用于现代 Python 版本（3.6+）。
Template 字符串：
- 适用于外部或用户提供的字符串

¡Vamos a practicar!

Python 中的正则表达式