Templates concept in PYTHON

What is Template ?

Template is a class of String module.

It allows for data to change without having to edit the application. It can be modified with subclasses. Templates provide simpler string substitutions . Templates substitution is “$“-based substitutions

How do I use a template in Python?

To use the Python Template class in our code, we need to:

• Import Template from the string module.
• Create a valid template string.
• Instantiate Template using the template string as an argument.
• Perform the substitution using a substitution method.

How it works ?

• Takes a string as a template with placeholder variables to be over written.
• You then Substitute the values in with a dictionary.The key being the placeholder name
• Placeholder names follow the same rules as variables naming in python

example program in python using templates

OUTPUT:

Template Errors

• No placeholder match,will result in a KeyError in which the template wasn't given a value for a placeholder

here we didn't provided the value for placeholder error,so we get key error

• Bad placeholder,will result in a ValueError.The placeholder started with an invalid character(placeholder when started with number)

here,the placeholder price is started with number ,so we get value error

Safe_substitute()

• Templates can handle these errors and give us back a string still if we use the method safe_substitute()
• You also get the placeholders in the returned string if there is an error with it.