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Video: High-Quality Code - Code Formatting (Bulgarian)

  • December 01, 2020
  • Nikolay Kostov (Nikolay.IT)

Topics covered:

  • Why Do We Need Code Formatting?
  • Formatting Methods
  • Formatting Types
  • Common Mistakes
  • Alignments
  • Automated Tools

Video (in Bulgarian)

Presentation Content

Code Formatting

Why do we need it? How can white spaces and parenthesis help us?

Any fool can write code that a computer can understand. Good programmers write code that humans can understand.

    public   const    string                    FILE_NAME
    ="example.bin"  ;  static void Main   (             ){
    FileStream   fs=     new FileStream(FILE_NAME,FileMode
    .   CreateNew)   // Create the writer      for data  .
    ;BinaryWriter w=new BinaryWriter     (    fs      );
// Write data to                               Test.data.
    for(  int i=0;i<11;i++){w.Write((int)i);}w   .Close();
    fs   .   Close  (  ) // Create the reader    for data.
    ;fs=new FileStream(FILE_NAME,FileMode.            Open
    ,  FileAccess.Read)     ;BinaryReader                r
    = new BinaryReader(fs);  // Read data from  Test.data.
     for (int i = 0; i < 11; i++){ Console      .WriteLine
    (r.ReadInt32                                       ())
    ;}r       .    Close   (   );  fs .  Close  (  )  ;  }
  • Good formatting goals
    • To improve code readability
    • To improve code maintainability
  • Fundamental principle of code formatting:
    • Any (consistent) formatting style that follows the above principle is good
    • Good formatting don’t affect speed, memory use or other aspects of the program

Formatting Blocks in C#

  • Put { and } alone on a line under the corresponding parent block
  • Indent the block contents by a single [Tab]
    • Visual Studio will replace the [Tab] with 4 spaces
  • Example:
if (some condition)
{
    // Block contents indented by a single [Tab]
    // VS will replace the [Tab] with 4 spaces
}

Formatting Blocks in JS

  • Put { at the end of the block and } alone on a line under the corresponding parent block
  • Indent the block contents by a single [Tab]
    • [tab] or spaces depends on the team style
  • Example:
if (some condition) {
    // Block contents indented by a single [Tab]
    // Choosing between [tab] and spaces depends
    //  on project formatting style
}

Why are Brackets Obligatory?

// swap left and right elements for whole array
for (var i = 0; i < MaxElements; i++)
{
    leftElement = left[i];
    left[i] = right[i];
    right[i] = leftElement;
}

// swap left and right elements for whole array
for ( var i=0; i<MaxElements; i++ )
    leftElement = left[i];
    left[i] = right[i];
    right[i] = leftElement;

Why are Brackets Obligatory?

x = 3+4 * 2+7;

x = (3 + 4) * (2 + 7);

Empty Lines between methods

  • Use empty line for separation between methods:
public class Factorial
{
    private static ulong CalcFactorial(uint num)
    {
        if (num == 0)
        {
            return 1;
        }
        else
        {
            return num * CalcFactorial(num - 1);
        }
    }

    static void Main()
    {
        ulong factorial = CalcFactorial(5);
        Console.WriteLine(factorial);
    }
}
  • Leave empty line between methods
  • Always use { and } after if

Methods Indentation

  • Methods should be indented with a single [Tab] from the class body
  • Methods body should be indented with a single [Tab] as well
public class Indentation_Example_
{
    private int Zero()
    {
        return 0;
    }
}
  • The entire method is indented with a single [Tab]
  • Method body is also indented

Brackets in Methods Declaration

  • Brackets in the method declaration should be formatted as follows:
private static ulong CalcFactorial(uint num)
  • Don’t use spaces between the brackets:
private static ulong CalcFactorial ( uint num )
private static ulong CalcFactorial (uint num)
  • The same applies for if-conditions and for-loops:
if (condition) { … }

for (int i = 0; i < 10; i++) { … }

Separating Parameters

  • Separate method parameters by comma followed by a space
    • Don’t put space before the comma
    • Correct examples:
private void RegisterUser(string username, string password);
RegisterUser("academy", "s3cr3t!p@ssw0rd");
  • Incorrect examples:
private void RegisterUser(string username,string password)
private void RegisterUser(string username ,string password)
private void RegisterUser(string username , string password)

Empty Lines

  • Use an empty line to separate logically related sequences of lines:
private List<Report> PrepareReports()
{
    List<Report> reports = new List<Report>();

    // Create incomes reports
    Report incomesSalesReport = PrepareIncomesSalesReport();
    Report incomesSupportReport = PrepareIncomesSupportReport();
    reports.Add(incomesSalesReport, incomesSupportReport);

    // Create expenses reports
    Report expensesPayrollReport = PrepareExpensesPayrollReport();
    Report expensesMarketingReport = PrepareExpensesMarketingReport();
    reports.Add(expensesPayrollReport, expensesMarketingReport);

    return reports;
}

Formatting Types

  • Formatting classes / structures / interfaces / enumerations
    • Indent the class body with a single [Tab]
    • Use the following order of definitions:
      • Constants, delegates, inner types, fields, constructors, properties, methods
      • Static members, public members, protected members, internal members, private members
    • The above order of definitions is not the only possible correct one

Formatting Types – Example in C#

public class Dog
{
    // Static variables
    public const string SPECIES = "Canis Lupus Familiaris";

    // Instance variables
    private int age;

    // Constructors
    public Dog(string name, int age)
    {
        this.Name = name;
        this.Аge = age;
    }

    // Properties
    public string Name { get; set; }

    // Methods
    public void Breath()
    {
        // TODO: breathing process
    }

    public void Bark()
    {
        Console.WriteLine("wow-wow");
    }
}

Formatting Conditional Statements and Loops

  • Formatting conditional statements and loops
    • Always use { } block after if / for / while, even when a single operator follows
    • Indent the block body after if / for / while
    • Always put a new line after a if / for / while block!
    • Always put the { on the next line (in C#)
    • Always put the { on the same line (in JavaScript)
    • Never indent with more than one [Tab]

Conditional Statements and Loops Formatting – Examples in C#

  • Correct examples:
for (int i = 0; i < 10; i++)
{
    Console.WriteLine("i={0}", i);
}
  • Incorrect examples:
for (int i = 0; i < 10; i++)
  Console.WriteLine("i={0}", i);

for (int i = 0; i < 10; i++) Console.WriteLine("i={0}", i);

for (int i = 0; i < 10;) {
    Console.WriteLine("i={0}", i);  i++; Console.WriteLine();
}
  • The { and } are missing
  • Never put multiple statements on the same line!
  • In C# the { should be on the next line

Using Empty Lines

  • Empty lines are used to separate logically unrelated parts of the source code
    • Don’t put empty lines when not needed!
public static void PrintList(List<int> ints)
{
    Console.Write("{ ");
    foreach (int item in ints)
    {
        Console.Write(item);
        Console.Write(" ");
    }

    Console.WriteLine("}");
}

static void Main()
{
    // …
  • An empty line separates the methods
  • An empty line after the foreach block

Misplaced Empty Lines – Example

for (int i = 0; i < 10;)
{
    Console.WriteLine("i={0}", i);  


        i++;


        Console.WriteLine();
}
  • What do these empty lines serve for?

Breaking Long Lines

  • Break long lines after punctuation
  • Indent the second line by single [Tab]
  • Do not additionally indent the third line
  • Examples:
if (matrix[x, y] == 0 || matrix[x-1, y] == 0 ||
    matrix[x+1, y] == 0 || matrix[x, y-1] == 0 ||
    matrix[x, y+1] == 0)
{ …

public void GetAllAbstractPaintings()
{
       var paintings = this.Database.Paintings.All()
         .Where(x => x.PaintingStyle == PaintingStyleType.Abstract)
         .OrderBy(x => x.Price)
         .ThenBy(x => x.DateCreated)
         .Select(x => x.OriginalPaintingPath)
         .ToList();
}

Incorrect ways to break long lines (in C#)

if (matrix[x, y] == 0 || matrix[x-1, y] ==
  0 || matrix[x+1, y] == 0 || matrix[x,
  y-1] == 0 || matrix[x, y+1] == 0)
{ …

if (matrix[x, y] == 0 || matrix[x-1, y] == 0 ||
      matrix[x+1, y] == 0 || matrix[x, y-1] == 0 ||
      matrix[x, y+1] == 0)
{ …

DictionaryEntry<K, V> newEntry
  = new DictionaryEntry<K, V>(oldEntry
  .Key, oldEntry.Value);

Breaking Long Lines in C# and JavaScript

  • In C# use single [Tab] after breaking a long line:
if (matrix[x, y] == 0 || matrix[x-1, y] == 0 ||
    matrix[x+1, y] == 0 || matrix[x, y-1] == 0 ||
    matrix[x, y+1] == 0)
{
    matrix[x, y] == 1;
}
  • In JavaScript use double [Tab] in the carried long lines:
if (matrix[x, y] == 0 || matrix[x-1, y] == 0 ||
       matrix[x+1, y] == 0 || matrix[x, y-1] == 0 ||
       matrix[x, y+1] == 0) {
    matrix[x, y] == 1;
}

Alignments

  • All types of alignments are considered harmful
    • Alignments are hard-to-maintain!
    • Modifying one line of code shouldn’t require modifying several others
  • Incorrect examples:
public void NotCool()
{
    var student          = new Student("Ivan", "Kolev", 21);
    var studentGrades    = new List<int>() { 2, 3, 4, 5, 6 };
    var school           = new SMG("Kopernik");
    var studenstInSchool = new List<Student>();
}

Automated Tools


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