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How to Find the Stinky Parts of Your Code [Part XXXII]by@mcsee
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How to Find the Stinky Parts of Your Code [Part XXXII]

by Maximiliano ContieriMarch 8th, 2023
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It smells because there are likely many instances where it could be edited or improved. Most of these smells are just hints of something that might be wrong. Therefore, they are not required to be fixed per se… (You should look into it, though.) Previous Code SmellsYou can find all the previous code smells (Part i - XXXI) here.
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It smells because there are likely many instances where it could be edited or improved.


Most of these smells are just hints of something that might be wrong. Therefore, they are not required to be fixed per se… (You should look into it, though.)

Previous Code Smells

You can find all the previous code smells (Part i - XXXI) here.


Let's continue...


Code Smell 156 - Implicit Else

We learn if/else on our first programming day. Then we forget the else.


TL;DR: Be explicit. Even with Else.

Problems

Solutions

  1. Write the explicit else

Context

If we early return on an IF sentence, we can omit the else part.


Afterward, we Remove the IF and use polymorphism.


That is when we miss the real cases.

Sample Code

Wrong

function carBrandImplicit(model) {
  if (model === 'A4') {
    return 'audi';
  }
  return 'Mercedes-Benz';
}

Right

function carBrandExplicit(model) {
  if (model === 'A4') {
    return 'audi';
  }
  if (model === 'AMG') {
    return 'Mercedes-Benz';
  }
  
  // Fail Fast
  throw new Exception('Model not found);
}

Detection

  • [x]Automatic


We can check syntax trees and parse them and warn for missing else.


We can also rewrite them and perform mutation testing.

Tags

  • Conditionals

Conclusion

This kind of smell brings a lot of public debate and hate.


We must exchange opinions and value each pro and cons.

Relations

Code Smell 102 - Arrow Code

Code Smell 36 - Switch/case/else if/else/if statements

More Info

Stop Using Implicit Else

When To Use Implicit Else

Fail Fast

How to Get Rid of Annoying IFs Forever

Credits

Photo by Elena Mozhvilo on Unsplash


The biggest issue on software teams is making sure everyone understands what everyone else is doing.


Martin Fowler


Code Smell 157 - Balance at 0

Today, I expected a payment in my wallet. The balance was 0. I panicked.


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

Problems

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

Code Smell 12 - Null

Code Smell 139 - Business Code in the User Interface

Code Smell 73 - Exceptions for Expected Cases

Code Smell 72 - Return Codes

More Info

Null: The Billion Dollar Mistake

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)


Software Engineering Great Quotes


Code Smell 158 - Variables Not Variable


You assign a value to a variable and use it but never change it.


TL;DR: Be declarative on mutability.

Problems

  • Readability
  • Honor the Bijection mutability.
  • Potential performance and memory issues.

Solutions

  1. Change the variable to a constant and be clear on its scope.

Refactorings

Refactoring 003 - Extract Constant

Refactoring 008 - Convert Variables to Constant

Context

We are always learning from the domain.


Sometimes we guess that a value can change with the MAPPER.


Later on, we learn it won't change.


Therefore, we need to promote it to a constant.


This will also avoid Magic Constants.

Sample Code

Wrong

<?php

function configureUser() {
  $password = '123456';
  // Setting a password on a variable is another vulnerability
  // And Code Smell
  $user = new User($password);
  // Notice Variable doesn't change
}

Right

<?php

define("USER_PASSWORD", '123456')

function configureUser() {  
  $user = new User(USER_PASSWORD);
}

// or 

function configureUser() {  
  $user = new User(userPassword());
}

function userPassword() : string {
  return '123456';
}

// Case is an oversimplification as usual

Detection

  • [x]Automatic


Many linters check if the variable has just one assignment.


We can also perform mutation testing, and try to modify the variable to see if the tests break.

Tags

  • Mutability

Conclusion

We must challenge ourselves and refactor when the variable scope is clear, and we learn more about its properties and mutability.

Relations

Code Smell 116 - Variables Declared With 'var'

Code Smell 127 - Mutable Constants

Code Smell 107 - Variables Reuse

Code Smell 02 - Constants and Magic Numbers

More Info

The Evil Power of Mutants

Disclaimer

Code Smells are just my opinion.

Credits

Photo by Noah Buscher on Unsplash


A complex system that works is invariably found to have evolved from a simple system that worked.


John Gall


CoDe SmElL 159 - mIxEd_cASeI

Serious development is done by many different people. We have to start agreeing.


TL;DR: Don't mix different case conversions

Problems

  • Readability
  • Maintainability

Solutions

  1. Choose a case standard


  2. Hold on to it

Context

When different people make software together, they might have personal or cultural differences.

Some prefer camelCase🐫, others snake_case🐍, MACRO_CASE🗣️, and many others.


The code should be straightforward and readable.

Sample Code

Wrong

{
    "id": 2,
    "userId": 666, 
    "accountNumber": "12345-12345-12345",
    "UPDATED_AT": "2022-01-07T02:23:41.305Z",
    "created_at": "2019-01-07T02:23:41.305Z",
    "deleted at": "2022-01-07T02:23:41.305Z"
}

Right

{
    "id": 2,
    "userId": 666, 
    "accountNumber": "12345-12345-12345",
    "updatedAt": "2022-01-07T02:23:41.305Z",
    "createdAt": "2019-01-07T02:23:41.305Z",
    "deletedAt": "2022-01-07T02:23:41.305Z"
  // This doesn't mean THIS standard is the right one
}

Detection

  • [x]Automatic

We can tell our linters about our company's broad naming standards and enforce them.


Whenever new people arrive at the organization, an automated test should politely ask him/her/.. to change the code.

Exceptions

Whenever we need to interact with out-of-our-scope code, we should use the client's standards, not ours.

Tags

  • Naming

Conclusion

Dealing with standards is easy.


We need to enforce them.

Relations

Code Smell 48 - Code Without Standards

More Info

What exactly is a name - Part I The Quest

All naming conventions

Disclaimer

Code Smells are just my opinion.

Credits

Photo by Wolfgang Hasselmann on Unsplash


If you have too many special cases, you are doing it wrong.


Craig Zerouni


Code Smell 160 - Invalid Id = 9999

Maxint is a very good number for an invalid ID. We will never reach it.


TL;DR: Don't couple real IDs with invalid ones. In fact: Avoid IDs.

Problems


  • You might reach the invalid ID sooner than your think.


  • Don't use nulls for invalid IDs either.


  • Coupling flags from caller to functions.

Solutions

  1. Model special cases with special objects.


  2. Avoid 9999, -1, and 0 since they are valid domain objects and implementation coupling.


  3. Introduce Null Object

Context

In the early days of computing, data types were strict.


Then we invented The billion-dollar mistake.


Then we grew up and modeled special scenarios with polymorphic special values.

Sample Code

Wrong

#include "stdio.h"
#include "stdlib.h"
#include "stdbool.h"
#define INVALID_VALUE 999

int main(void)
{    
    int id = get_value();
    if (id==INVALID_VALUE)
    { 
        return EXIT_FAILURE;  
        // id is a flag and also a valid domain value        
    }
    return id;
}

int get_value() 
{
  // something bad happened
  return INVALID_VALUE;
}

// returns EXIT_FAILURE (1)

Right

#include "stdio.h"
#include "stdlib.h"
#include "stdbool.h"
// No INVALID_VALUE defined

int main(void)
{    
    int id;
    id = get_value();
    if (!id) 
    { 
        return EXIT_FAILURE;
        // Sadly, C Programming Language has no exceptions
    }  
    return id;
}  

get_value() 
{
  // something bad happened
  return false;
}

// returns EXIT_FAILURE (1)

Detection

  • [x]Semi-Automatic


We can check for special constants and special values in the code.

Tags

  • Null

Conclusion

We should use numbers to relate to the external identifiers.


If no external identifier exists, then it is not a number.

Relations

Code Smell 120 - Sequential IDs

Code Smell 12 - Null

More Info

Null: The Billion Dollar Mistake

Y2K22 - The Mistake That Embarrasses Us

Disclaimer

Code Smells are just my opinion.

Credits

Photo by Markus Spiske on Unsplash


Bugs lurk in corners and congregate at boundaries.


Boris Beizer


5 more code smells are coming soon…