Implement `input(prompt)` by kmr-srbh · Pull Request #2655 · lcompilers/lpython

@Shaikh-Ubaid , there is a small issue occurring here. Because we are directing calls to FileRead, input() itself is not having a return type and value. So, an expression like n: i32 = i32(int(input("Enter a number: ")))) leads to an exception. A simple program:

name: str = input("Your name: ")
print("Hello,", name)

gives the following output

(base) saurabh-kumar@Awadh:~/Projects/System/lpython$ ./src/bin/lpython ./examples/example.py
Your name: Segmentation fault (core dumped)

I request you to see if the implementation is correct. Instead of a separate function create_Input() with a call inside if (call_name == "input"), I am using the complete piece of code here.

@kmr-srbh the following works:

% cat examples/expr2.py 
name: str = "                "
name = input("Your name: ")
print("Hello,", name)
% python examples/expr2.py
Your name: John
Hello, John
% lpython examples/expr2.py
Your name: John
Hello,John

We just needed name to have initial length/space so that we could write to it the string read from stdin.

We need to see what other better alternative approaches can be for the workaround (for name length) in #2655 (comment).

We need to see what other better alternative approaches can be for the workaround (for name length) in #2655 (comment).

You are right @Shaikh-Ubaid. How do we go about working a fix for the return type issue? This is a real problem. I am new to this area of the code-base and learning.

Let's modify the semantics of the FileRead ASR node: if the "value" expr argument is an allocatable string, then the backend (LLVM/WASM, etc.) implementation of the FileRead node will allocate the string to hold the whole input, and assign it to it.

Let's modify the semantics of the FileRead ASR node: if the "value" expr argument is an allocatable string, then the backend (LLVM/WASM, etc.) implementation of the FileRead node will allocate the string to hold the whole input, and assign it to it.

@certik Do you mean handling String_t here?