PromptTemplate benefits over f-string

[amitwats]

I saw a basic tutorial of lang chain
which gave an example of using a "PromptTemplate" to ask a question

template='''
Question: {question_text} 

Lets think step by step

Answer :

'''
prompt=PromptTemplate(template=template, input_variables=['question'])

user_input= input("Whats the question")

prompt.format(question=user_input

Not sure whats the advantage of using a "PromptTemplate" instead of an f-string. I mean we could just create a prompt=f"Question '{question_text}' Lets think step by step"

Like this

user_input= input("Whats the question")


template=f'''
Question: {user_input} 

Lets think step by step

Answer :

'''

# use template to fire a prompt command

Rt?

So whats the advantage of Lang Chain here?

[ilanaliouchouche]

Hi,
Personally I would say that the main reason is the integration of the class with all the other classes and functions. We can also find additional params like metadata or tags for traceability (even if I have the impression that they are not widely used). But overall there are no big differences with an f-string (as said here :
This is just a simple implementation that can easily be replaced with f-strings (like f"insert some custom text '{custom_text}' etc"). However, using Langchain’s PromptTemplate object, we can formalize the process, add multiple parameters, and build prompts with an object-oriented approach.)

[Nagidrop]

If I'm not wrong you can partially format PromptTemplate, while in f-string you have to fully format all values. For example, for a string like put {content1} before {content2}, for PromptTemplates you can put only {content1} and still doing good, while in f-string it will also require {content2} to be filled in.