Python & Neovim

Table of contents:

language & text editor

What do you need to have?

Hej, today we begin learning with Nutek to be able to use it how I see it fit. First be sure you have one of the following:

  • neosb/nutek-core:0.4.0 from Docker Hub
  • Nutek from crates.io or Github - working on a fix
  • You could follow on with Python3, pip, venv and Neovim

What you will learn?

I want to show you few Python use cases and how to write code in Neovim. We will use this in future lessons and hacking activities that will surely come to us as we go.

I'm not the only source of truth you should rely on, so try to bing-search (which is the part of Nutek) or use Google to look-up interesting parts and to broaden your knowledge.

Where to look for answers?

I give you some links that might help you in the beginning.

Neovim is compatible version of Vim which is Vi improved, it's one of the basic text editor found on most of the UNIX-like operating systems, thus knowing how to use it is likely to payoff int the future :)

Python one of the most used programming languages, also one of the easiest to learn. So without bothering you with developers jargon...

3.. 2.. 1.. 🚀

First of all, to start Neovim type nvim in your terminal, or if you are ready to edit a text file, type nvim my_first_python_script.py. .py extension tells nvim that it's a Python file and if you use Nutek or nutek-core, after first start you will be given a chance to install coc-jedi which helps a lot with Python files. Keep pressing <Enter> untill it's done. I have preinstalled there, for you too, Github Copilot, so just.

viml: 

:Copilot setup

inside Neovim, confirm your credentials on Github, and have a helping hand ready to assist you with AI generated snippets of code.

Now. To make the first script a little bit challenging, let's use the my_first_python_script.py nvim window and write as follows.

viml: 

:tabnew
:terminal
<i>
python3 -c "print('Hej piękna!')"<Enter>

In context of Vi, Vim and Neovim <i> means pressing the i keyboard key. There is a lot about text in operating systems, especially UNIX-es, where every part of the operating system is a text file and Windows sometimes even borrows the thinking, e.g. /etc/hosts/ file. To the UNIX system family belongs Linux flavours like Debian, Ubuntu, Mint, Arch, Fedora, openSUSE, Red Hat Enterprise Linux; macOS, BSD based systems, freeBSD, openBSD. For now we won't be learning how to cope with OS, right now we want to write something, then we might know how to do something with operating system in terminal and in scripts.

Back on track. You should see now a response from your terminal saying to you Hello beauty in Polish. We used python3 and a switch -c which tells Python to run the code in between quotes. This is called an inline script. Now please press:

viml: 

<C-\>
<C-n>

It will exit terminal mode and let you operate Neovim normally. It's Ctrl+backslash and Ctrl+n.

Right now I want you to get to previos tab.

viml: 

:tabprevious

You might also autocomplete the statement with a <tab>, or use mouse to switch tabs, if have one, but mouse support depends on your configurations, and we want to stay focused, so using only keyboard might really help you stay as creative as it can be. Now type the comment after # sing and if you use Github Copilot, when you press <Enter> and wait a second or two, you should get a proposition to autocomplete the print statement. Agree with <tab>, dismiss with <ctrl-]>, and search for other suggestion with <alt-]>.

python: 

 hacking rules!<Enter>
print("Hacking Rules!")

You have your first script in text file. So save it. First get out of insert mode with <Esc> to get to normal mode, then please type.

viml: 

:write

I want to run it in a window, which will be visible in this tab, to do it follow on with this commands which will close all the other tabs, split window horizontally, switch to other window, open terminal, run your script and exit Neovim.

viml: 

:tabonly
<C-w+s>
<C-w+j>
:terminal
<i>
python3 my_first_python_script.py
<Enter>
<C-\>
<C-n>
:q
:wqa

You should know now what is the coolest computer activity 🥷.

What we learned so far?

Neovim

  • how to open a text file (nvim filename)
  • how to create new tab (:tabnew)
  • how to open the terminal (:terminal), get into insert mode (<i>), execute inline Python script (-c "python code here") and exit the terminal insert mode (<C-\><C-n>)
  • how to write text (<i>), exit from insert mode (<Esc>) and write changes to file (:write)
  • close all the other tabs (:tabonly)
  • split window horizontally (<C-w+s>) or vertically (<C-w+v>) and go to other windows (<C-w+h/j/k/l>) - where h is left, j is down, k is up, and l is left and it works with moving around the text in normal and visual mode
  • close tab, window, or just exit Neovim (:q)

Python

  • how comment looks like (# text that is not a code after pound sign)
  • how to output text to terminal (print("this will be the output")

Copilot 👩🏻‍💻

  • he know what do you mean if you provide enough clues, like a comment imported modules, docstring, class name, variables, method or any other part of meta that is an input for an AI generated guess
  • accept suggestion with <tab>
  • ask for next suggestion with <alt-]>
  • dismiss suggestion with <ctrl-]>

Flying higher

Open new file.

shell: 

nvim learning_to_fly.py

And write a comment

python: 

 that prints number from 16 to 0.
 number is divisible by 4 display 💣.
 loop finish print 💥

Press <Enter>, write f, wait for suggestion, press tab to accept, <Enter> once more, <tab> to accept, <Enter> and <tab> again. You should have now fully functional script that does exactly what it's asked to do. You should have to have Copilot setup to be able to do this. Exit insert mode with <Esc> and write the file with :write. If you're using Nutek, open new bash sessions with nutek, or if you're using only Docker, run docker exec -it name-of-your-container bash. I mean, that you need other terminal window where you can access the file we're working on right now.

shell: 

python3 learning_to_fly.py

What you learned from this script?

For loop

In one form of it, for loop runs for the exectly specified times code which is after the colon sign. Next lines are indented, and will be exucuted. You can ask to skip one iteration with continue, exit loop with break wich will resume code flow of unindented lines. It also saves a variable i which is the current value of the loop.

python: 

for i in "don't go to school, become ninja!":
    if i == "!":
        print("🥷")

As you can see, the value of variable can be in many forms too.

If, elif and else statement

Check if condition is true. Uses boolean logic to check if code after colon can be run. It can be True or False. If the condition doesn't stands, goes to next elif check, or straight to else. Both are optional, but there can be many elif checks, but one else statement.

python: 

if True == False:
    # this will never run
    pass
elif not True == True:
    # this will never run
    pass
elif False == (not False):
    # this will never run
    pass
else:
    # this will run because it does not check for condition \
    # only if it is the last checked statement \
    # if one of the if, or elif will run, after the end of \
    # indentation the program flow will resume after the whole \
    # if check
    print("This is my last resort")

There are also other methods to use if statements. With and clause or or clause. Let me show you.

And

python: 

if True and False:
    # this will never run
    pass
elif True and True and False:
    # this will never run
    pass
elif False and False:
    # this will never run
    pass
elif True and True:
    print("We've got a winner!")

Or

python: 

if True or False:
    # this will run
    print("Hmmm... Why we do this?")

if True or True:
    # this is another check that will run
    print("Simply the best")

if False or False:
    # this will never run
    pass

To say it's kind of magic is not enough. and check is True only if all of the parts of equation are True, but or clause let you pass if check when only one part is True. You can help yourself with parentheses (True and (False or True)).

Range function

Functions are parts of code that can be run many times saving you typing, so you dont write Hello world and Hello Agnes two times but instead you define a function and then substitue arguments in your source code as variables that help you save time. It's like cooking. You could add two spoons of sugar, but one spoon of flour.

python: 

def hello(who):
    """
    friendly greeting
    arguments:
    who (str): who to greet
    returns:
    greeting (str): friendly greeting
    """
    greeting = "Hello " + who + "! How are you?"
    return greeting
hello("Agnes")
hello("Asia")

You learned that range function takes 3 arguments, with optional step and is invoked using parentheses, range(0, 16). Check that with hovering over the name of method (aka function) and pressing <K>. You can see that when hovering over your hello function and again pressing <K>, you can read what is called dockstring, think about it as helping me understand what do you wanted from me, or how it should run exactly. Then use Copilot.

To invoke hello function, use hello("world")

List

range(0, 4) is the same as a list of four items, starting with 0 - [0, 1, 2, 3] to access/select an item in a list you use brackets [x]. So the first element is [0] and last is [-1] or in our case [3].

Variable

We have also asigned a number to variable, and a character to variable. Variable is a placeholder for your values, that let's you use stored value in other parts of your program. Variables can be numbers, strings, results of your calculations, methods, classes, lists, dictionaries aka hashmaps, tuples - simply put, objects and basic data types. Check for type of your data.

python: 

data_type = type("this is str class")
print(data_type)

You should know that you will be using this a lot if you want to make programs and scripts.

Get request

First of all, be sure that you have pip and venv installed. Now we will make a virtual environment for the next script to run. Venv is used to package the program so it can be easily portable and decoupled from other Python scripts. You might want to have one package installed, or ten, but you don't need them in all of your scripts, so you make a virtual environment with venv and safely install what you need now and safely remove later.

shell: 

mkdir my_first_get_request
cd my_first_get_request
python3 -m venv get_request
source get_request/bin/activate
python3 -m pip install requests

First you created a directory called my_first_get_request, then you moved the current working directory to it, then created virtual environment called get_request and activated it, then installed requests package only for this environment.

Exit from previous Neovim session if you haven't already, and be sure to first activate newly created Python environment and again run nvim my_get_request.py

First of all we start with a bad request, which will give us some intuition how the http protocol works.

python: 

import requests
import json

 a bad get request to httpbin.org then show the error message \
 print the headers.
response = requests.get("http://httpbin.org/status/404")
print(response.status_code)
print(response.reason)
print(response.headers)

Then try again with another get request, that will send back some data.

python: 

 a get request to httpbin.org/get with some parameters.
response = requests.get("http://httpbin.org/get",
        params={"name": "Szymon", "age": 34}
    )
print(response.status_code)
print(response.reason)
 the query string from the url.
query_string = response.url
print(query_string)
 the json data from the response.
data = response.json()
 print json data.
print(json.dumps(data, indent=4, sort_keys=True))

Here we see a classic example of getting data from an API. We provide parameters, name and age, this would be likely a query to database. In an origin header key, you can see value of your IP address, you should know that it's always known, unless you are connected to proxy like TOR or other kind of VPN that could route your request.

Change request to something else.

python: 

response = requests.get("http://httpbin.org/get",
        params={"name": "John", "surname": "Dillinger"},
        headers={"Accept": "application/json"}
    )

You have encoded your first json request! JSON, stands for JavaScript Object Notation which is very common format of exchanging data between services. Most of the API's made to be available on the web support it.

So far you've learned how to get data from API, what about making a class that will be an actual object of human cosmic conquer? But first let's get some hands dirty with more Neovim commands. We need fuel for our rocket science 🚀

Working with files

:edit .

2022-09-02 19:37:24 +0200 by Neosb

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