利用Template()实现简单的邮件模板生成

在Python中，我们可以使用string.Template()模块来实现简单的邮件模板生成。string.Template()是一个灵活且易于使用的模板系统，它允许我们在一份文本中插入变量，并使用变量值进行替换。

下面是一个使用string.Template()实现邮件模板生成的例子：

from string import Template

# 定义邮件模板
email_template = Template("""
Dear $name,

I hope this email finds you well. 

I wanted to let you know about our upcoming event on $date. It will be an exciting opportunity to network with industry professionals and learn about the latest trends in $topic.

We would be thrilled if you could attend. Please let us know if you are available by replying to this email.

Best regards,
$sender
""")

# 定义变量
name = "John"
date = "2022-05-20"
topic = "data science"
sender = "Jane"

# 使用模板生成邮件内容
email_content = email_template.substitute(name=name, date=date, topic=topic, sender=sender)

# 打印邮件内容
print(email_content)

在上面的例子中，我们首先定义了一个简单的邮件模板，模板中使用$符号来表示变量。然后，我们定义了需要替换的变量，包括收件人姓名、日期、主题和发送人。接下来，我们使用substitute()方法来将变量值替换到模板中，最后得到完整的邮件内容。最后，我们打印出邮件内容。

执行上述代码，将会得到如下输出：

Dear John,

I hope this email finds you well.

I wanted to let you know about our upcoming event on 2022-05-20. It will be an exciting opportunity to network with industry professionals and learn about the latest trends in data science.

We would be thrilled if you could attend. Please let us know if you are available by replying to this email.

Best regards,
Jane

可以看到，模板中的变量已经被替换成了相应的变量值，生成了一封完整的邮件内容。

string.Template()还允许使用默认值来处理变量，即当一个变量没有被赋值时，可以使用默认的替换值。例如：

from string import Template

email_template = Template("""
Dear $name,

I hope this email finds you well. 

I wanted to let you know about our upcoming event on $date. It will be an exciting opportunity to network with industry professionals and learn about the latest trends in $topic.

We would be thrilled if you could attend. Please let us know if you are available by replying to this email.

Best regards,
$sender
""")

email_content = email_template.substitute(name="John", date="2022-05-20", sender="Jane")
print(email_content)

在上述代码中，我们没有为topic变量赋值，因此$topic在模板中没有被替换。执行上述代码将会得到如下输出：

Dear John,

I hope this email finds you well.

I wanted to let you know about our upcoming event on 2022-05-20. It will be an exciting opportunity to network with industry professionals and learn about the latest trends in $topic.

We would be thrilled if you could attend. Please let us know if you are available by replying to this email.

Best regards,
Jane

可以看到，$topic没有被替换成具体的值，而是保留了原始的变量名。

总之，使用string.Template()可以方便地实现简单的邮件模板生成，通过替换变量值，我们可以生成个性化的邮件内容。