20 stories with 5 code smells each are 100 code smells, right?

Previous Code Smells

• Part I

• Part II

• Part III

• Part IV

• Part V

• Part VI

• Part VII

• Part VIII

• Part IX

• Part X

• Part XI

• Part XII

• Part XIII

• Part XIV

• Part XV

• Part XVI

• Part XVII

• Part XVIII

• Part XIX

Let's continue...

Code Smell 96 - My Objects

You don't own objects.

TL;DR: don't use my as a name prefix.

Problems

• Lack of context
• Bijection Fault

Solutions

1. Remove my prefix.
2. Change to a role suggesting name.

Context

Several old tutorials use the word 'my' as a lazy name. This is vague and lead to context mistakes.

Sample Code

Wrong

MainWindow myWindow = Application.Current.MainWindow as MainWindow;

Right

MainWindow salesWindow = Application.Current.MainWindow as MainWindow;

/*

Since window is instanciated, we are currently working
with a specialized window playing a special role

*/

Detection

• [x]Automatic

We can tell our linters and static checkers to search for this prefix and warn us.

Tags

• Naming

Conclusion

Avoid using my. Objects change according to the usage context.

More Info

• What exactly is a name — Part II Rehab

Credits

Photo by Michał Bożek on Unsplash

Thinking about my experience of modifying code, I see that I spend much more time reading the existing code than I do writing new code. If I want to make my code cheap, therefore, I should make it easy to read.

Kent Beck

Software Engineering Great Quotes

Code Smell 97 - Error Messages Without Empathy

We should take special care with error descriptions for the users (and ourselves).

TL;DR: Use meaningful descriptions and suggest corrective actions.

Problems

• The Least Surprise Principle

Solutions

1. Use declarative error messages
2. Show clear exit actions

Context

Programmers are seldom UX experts.

We also underestimate the fact we can be on both sides of the counter.

Sample Code

Wrong

alert("Cancel the appointment?", "Yes", "No");

// No consequences
// Options not clear

Right

alert("Cancel the appointment? \n" +
      "You will lose all the history", 
      "Cancel Appointment", 
      "Keep Editing");

// Consequences are clear
// Choice options have context

Detection

• [x]Manual

We need to read all exception messages in code reviews.

Tags

• Exceptions
• UX

Conclusion

We need to think in our end users when raising exception or showing messages.

Credits

Photo by visuals on Unsplash

While it is a known fact that programmers never make mistakes, it is still a good idea to humor the users by checking for errors at critical points in your program.

Robert D. Schneider

Code Smell 98 - Speling Mistakes

Spelling and readability are very important for humans and not important for machines.

TL;DR: Take care of your names.

Problems

• Readability
• Harder to search terms in code.

Solutions

1. Spellcheck your code.
2. Use an IDE with spellchecking

Context

Many of us don't speak English as our first language.

We need to have extra care for our texts and names.

This article has a typo in its title as proof of context and also a clickbait😀

Sample Code

Wrong

comboFeededBySupplyer = supplyer.providers();

Right

comboFedBySupplier = supplier.providers();

Detection

Tags

• Readability
• Naming
• Code Styling

Conclusion

Pay close attention to your names.

You will probably be the person reading the code in a few months.

Relations

Code Smell 48 - Code Without Standards

More Info

What exactly is a name — Part I The Quest

What exactly is a name — Part II Rehab

Credits

Photo by Brett Jordan on Unsplash

Inside every well-written large program is a well-written small program.

C.A.R. Hoare

Code Smell 99 - First Second

How many times do we see lazy argument names?

TL;DR: Name your arguments according to the role and not the accidental position

Problems

• Readability
• Intention Revealing Names

Solutions

1. Use meaningful names

Context

When writing methods, we usually don't stop to find decent names.

We never refactor the obvious, neither.

Sample Code

Wrong

class Calculator:
  def subtract(self, first, second):
    return first - second

class CalculatorTest  
  def test_multiply():
    assert equals(first, second)

Right

class Calculator:
  def subtract(self, minuend, subtrahend):
    return minuend - subtrahend

class CalculatorTest  
  def test_multiply():
    assert equals(expectedValue, realValue)

Detection

• [x]Manual

We can warn for forbidden words like 'first' and 'second' as argument names.

Tags

• Readability

Conclusion

Always follow rule suggesting parameter.

Name your collaborators according to the role.

Relations

Code Smell 65 - Variables Named after Types

More Info

What exactly is a name — Part II Rehab

Credits

Photo by Priscilla Du Preez on Unsplash

Final source code is the real software design.

Jack Reeves

Code Smell 100 - GoTo

GOTO was considered harmful 50 years ago

TL;DR: Don't ever use GoTo.

Problems

• Readability
• Hard to follow code

Solutions

1. Replace GOTO with structured code
2. Use exceptions

Context

I started programming in Basic.

GOTO was heavily abused there.

I had to learn structured programming from scratch in Rehab mode.

Sample Code

Wrong

for x < 0 {
    if x > -1e-09 {
      goto small
    }
    z = z / x
    x = x + 1
  }
  for x < 2 {
    if x < 1e-09 {
      goto small
    }
    z = z / x
    x = x + 1
  }

  if x == 2 {
    return z
  }

  x = x - 2
  p = (((((x*_gamP[0]+_gamP[1])*x+_gamP[2])*x+_gamP[3])*x+_gamP[4])*x+_gamP[5])*x + _gamP[6]
  q = ((((((x*_gamQ[0]+_gamQ[1])*x+_gamQ[2])*x+_gamQ[3])*x+_gamQ[4])*x+_gamQ[5])*x+_gamQ[6])*x + _gamQ[7]
  return z * p / q

small:
  if x == 0 {
    return Inf(1)
  }
  return z / ((1 + Euler*x) * x)
}

Right

for x < 0 {
    if x > -1e-09 {
      return small(x, z)
    }
    z = z / x
    x = x + 1
  }
  for x < 2 {
    if x < 1e-09 {
      return small(x, z)
    }
    z = z / x
    x = x + 1
  }

  if x == 2 {
    return z
  }

  x = x - 2
  p = (((((x*_gamP[0]+_gamP[1])*x+_gamP[2])*x+_gamP[3])*x+_gamP[4])*x+_gamP[5])*x + _gamP[6]
  q = ((((((x*_gamQ[0]+_gamQ[1])*x+_gamQ[2])*x+_gamQ[3])*x+_gamQ[4])*x+_gamQ[5])*x+_gamQ[6])*x + _gamQ[7]
  return z * p / q

small(x, z) {
  if x == 0 {
     return Inf(1)
   }
   return z / ((1 + Euler*x) * x)
 }
}

Detection

• [x]Automatic

In languages supporting GOTO, our linters can warn us against its usage.

Tags

• Readability

Conclusion

We acknowledged GOTO problems a few decades ago.

The problem is still present in modern languages like GoLang, PHP, Perl etc.

Most programmers luckily avoid GOTO sentence. Next goal will be to consider harmful null usage.

Courtesy XKCD

Relations

Code Smell 12 - Null

More Info

• Goto Statement considered harmful
• Wikipedia

Credits

Photo by Jens Johnsson on Unsplash

It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration.

Edsger Dijkstra

Software Engineering Great Quotes

And that’s all for now, We have hit 100 milestone.

The next article will explain 5 more code smells!