TL;DR: Null is not 0. Error is not 0. just 0 is 0.

Problems

• Nulls

• UX

• Usability

Solutions

1. Make a clear distinction between a Zero and an error.

Context

I read a lot about security issues.

Especially on crypto.

Last week, I read about a crypto hack thread.

When my wallet showed me 0 as a balance, I panicked.

It was just a UX smell.

The blockchain was unreachable 💩

Sample Code

Wrong

"""
Below code is automatically generated by code-davinci-002 on GTP3 Codex

1. check balance with blockchain
2. If blockchain is unreachable show 0 as the balance
"""

import requests
import json

def get_balance(address):
    url = "https://blockchain.info/q/addressbalance/" + address
    response = requests.get(url)
    if response.status_code == 200:
        return response.text
    else:
        return 0

Right

"""
Below code is automatically generated by code-davinci-002 on GTP3 Codex

1. check balance with blockchain
2. If blockchain is unreachable throw an error
"""

import requests
import json

def get_balance(address):
    url = "https://blockchain.info/q/addressbalance/" + address
    response = requests.get(url)
    if response.status_code == 200:
        return response.text
    else:
        raise BlockchainNotReachableError("Error reaching blockchain")

Detection

[X] Manual

This is a design smell.

We can find patterns when an exception or return code is thrown and masked with a 0.

Tags

• UX

Conclusion

Always follow The Least Astonishment principle as a guide.

Relations

More Info

Credit

Photo by Jasmin Sessler on Unsplash

Disclaimer

Code Smells are just my opinion.

My real criticism with Null is that it brings back again unnecessarily all the agony of having to choose whether to run your program fast without checking or run it slow with checking.

Tony Hoare (Null Inventor)

---

This article is part of the CodeSmell Series.