Modular•14mo ago

How do I open files to read/write in Mojo?

I want to do the equivalent of the following Python code:

with open(file.txt, 'r') as file:
  x = file.read()

with open(file.txt, 'r') as file:
  x = file.read()

How can I do this?

23 Replies

sa-code•14mo ago

You can use @lukas 's lib for now: https://github.com/lsh/shims

GitHub

GitHub - lsh/shims: Utils for mojo projects

Utils for mojo projects. Contribute to lsh/shims development by creating an account on GitHub.

bhavnicksmOP•14mo ago

@sa-code How do you use this repository to read files? The read has code but there's no example usage, so it's hard to understand

lukas•14mo ago

The read code has an example at the top of the file

bhavnicksmOP•14mo ago

Thanks, will try it out!

Tenesis•14mo ago

@lukas can you give an example on how to write files as well? Thanks a lot!

lukas•14mo ago

I haven’t written a wrapper for that yet I haven’t had a need, but will probably get around to it soon

Tenesis•14mo ago

I see. So as far as we know there's currently no way to write to file in Mojo yet?

lukas•14mo ago

You can call the CAPIs i.e write your own fwrite wrapper in the same way I did an fread wrapper

Tenesis•14mo ago

Cool, I can try that out Thanks!

Tenesis•14mo ago

Here we go" https://github.com/ShuzhaoFeng/mojo-minwa

GitHub

GitHub - ShuzhaoFeng/mojo-minwa: The minimal library you need to wr...

The minimal library you need to write / append file in Mojo - GitHub - ShuzhaoFeng/mojo-minwa: The minimal library you need to write / append file in Mojo

lukas•14mo ago

Nice 🙂 @Tenesis thought I'd ping you that I've since added a buffered writer

Tenesis•14mo ago

Awesome. 🥳 Thanks Lukas

lukas•14mo ago

By the way there’s now the open method available, but I’m pretty sure it’s not buffered yet, so its use will depend on what you’re doing

Elaid Tebabkha•14mo ago

It is simple with the version 0.4.0 , you have to see the documention of this version 🙏:mojo: :python:

bhavnicksmOP•14mo ago

Thanks @Elaid Tebabkha! 🩵 Will check it out now

ModularBot•14mo ago

Congrats @bhavnicksm, you just advanced to level 1!

bhavnicksmOP•14mo ago

@Elaid Tebabkha @lukas I was trying out the open method yesterday and I am facing issues with both reading and writing to a file. Mojo v0.4 doesn't seem to be able to parse it properly. Here's a screenshot of what I faced, and the code I was trying to execute

Balderdash•14mo ago

from pathlib.path import cwd
from pathlib.path import Path

from python import Python

fn main() raises:
    let currentPath = cwd()
    let file = currentPath/"my_file.txt"
    
    with open(file, "w") as f:
        f.write("Hello, world!")

    with open(file, "r") as f:
        print(f.read())

    let os = Python.import_module("os")
    os.remove(file.path)

from pathlib.path import cwd
from pathlib.path import Path

from python import Python

fn main() raises:
    let currentPath = cwd()
    let file = currentPath/"my_file.txt"
    
    with open(file, "w") as f:
        f.write("Hello, world!")

    with open(file, "r") as f:
        print(f.read())

    let os = Python.import_module("os")
    os.remove(file.path)

It's a working example .. you may add raises to your main function ?

bhavnicksmOP•14mo ago

@Balderdash Oh with raises it seems to work! Thanks Do you know why this works though? I don’t understand this properly

Balderdash•14mo ago

When you call a function, which throws an exception you need either to catch and handle it or define in your function by using key 'raises' its given to its caller to handle it.

Elaid Tebabkha•14mo ago

Or use try except finally.🙏

bhavnicksmOP•14mo ago

Yes, try-except also seems to work

Elaid Tebabkha•14mo ago

You can also write The code in python an import it inside the Mojo code like a PythonObject and execute the mojo code .

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How do I open files to read/write in Mojo?