- Understand Errors in Python
- Error Handling with try/except statements
- How to suppress Errors
📃Error Handling In Python:
It's very common to get errors in Python, especially during development. Until now I just told you to ignore them and that's not the best advice... So let's look into Error Handling.
Firstly, we need a simple error so we can look into it. Let's break a math law and try to divide a number by 0.
When an error occurs, you’ll see a traceback message of the last call that includes:
🔹File Name
🔹Code Line with Error
🔹Python code
🔹Error Type with Description (ZeroDivisionError in this case)
Usually, you would only need to look at the line number and the error message itself. Usually, that's enough to understand what has happened.
At first some error messages are going to be confusing, but once you solve them a few times it will come as a second nature. If confused - Ask Chat GPT about the error messages, it will break it down into human dialect.
Basic Error Handling with Try-Except
To handle errors in Python we need to use try/except statements.
Here's what's going to happen...
Python will start executing trycode block. If there are no errors, then it will finish try-block and ignore whatever is in except-block.
❌ However, if you get an error inside of try block, instead of crashing your script, it will suppress it and execute whatever you wrote in except block. In this case pass means do nothing, so we will only suppress an error.
💡It's okay to suppress errors in development, but it should be avoided in production.
The general rule is - if you have a piece of code that might encounter errors, then it's good idea to introduce an error handling. It can be as simple as catch and report.
We could also write something in the except to be more descriptive.
This time we will see messages `'Error has happened' and 'Hello World', because we had an error in the try block, so it triggered the except part.
💡 This is the standard error handling in python, especially for beginners.
Handling Specific Errors
Let's look a little deeper into error handling. It might be more advanced, but sometimes you want to be more specific with handling your errors.
You can specify multiple except blocks for different kind of error. But to be honest, that is more relevant on bigger scale development, so 99% of you won't use it. But it's good to know.
So, if you would want handle ZeroDivisonError specifically, you would write like this:
If a ZeroDivisionError occurs, this will print a more useful message instead of a generic error message. Otherwise you will get an error in the console, because it won't be handeled.
Catching Multiple Errors
You can also catch multiple errors at once like this:
Getting the Error Message
While we should avoid all errors in the final tool, errors are very important during development. So, make sure you don't supress all your error messages too early, and then wonder why nothing works.
You could avoid using try/except blocks until later, or you could actually print the error message without crashing you code.
If you want to get a very simple and brief description, you could use syntax like this:
This prints the actual error message (division by zero), which can be helpful for debugging.
But I would recommend you to use traceback package, to get more descriptive error message, exactly how you see it in the console.
So you would write something like this:
This prints the full traceback, including the file, line number, and exact error message, which is useful for debugging.
Summary
In general, error handling is a very important part of writing robust python code. You should always think about how you could break your script, so you can come up with an error handling before it even happened.
Open code editor and create a few errors, and try to handle these errors yourself by using simple
try/exceptstatements.It will also help you to use a lot of print statements before, after and especially inside of your
try/exceptblocks. This will help you understand how it is being executed so you can prepare for it in the future.Experiment with errors and don't be afraid of them. They just tell you that you did something wrong, nothing more than that.
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