Coding Style

QSanguosha Coding Style

This is an overview of the low-level coding conventions we use when writing QSanguosha code.
This style is developed by Qt. Since our project is based on Qt, we follow the Qt Coding Style.

indentation

• 4 spaces are used for indentation
• Spaces, not tabs!

Declaring variables

• Declare each variable on a separate line
• Avoid short or meaningless names (e.g. “a”, “rbarr”, “nughdeget”)
• Single character variable names are only okay for counters and temporaries, where the purpose of the variable is obvious
• Wait when declaring a variable until it is needed

    // Wrong
    int a, b;
    char *c, *d;

    // Correct
    int height;
    int width;
    char *nameOfThis;
    char *nameOfThat;

• Variables and functions start with a lower-case letter. Each consecutive word in a variable’s name starts with an upper-case letter
• Avoid abbreviations

    // Wrong
    short Cntr;
    char ITEM_DELIM = '\t';

    // Correct
    short counter;
    char itemDelimiter = '\t';

• Classes always start with an upper-case letter. Public classes start with an upper case letter (Button). Public functions most often start with a lower case letter (toJsonString).
• Acronyms are camel-cased (e.g. QXmlStreamReader, not QXMLStreamReader).

Whitespace

• Use blank lines to group statements together where suited
• Always use only one blank line
• Always use a single space after a keyword (including non-standard keywords such as foreach) and before a curly brace:

    // Wrong
    if(foo){
    }

    // Correct
    if (foo) {
    }

    // Wrong
    foreach(const ServerPlayer *p, room->getAlivePlayers()){
    }

    // Correct
    foreach (const ServerPlayer *p, room->getAlivePlayers()) {
    }

• For pointers or references, always use a single space between the type and '' or '&', but no space between the '' or '&' and the variable name:

    char *x;
    const QString &myString;
    const char * const y = "hello";

• Surround binary operators with spaces
• No space after a cast
• Avoid C-style casts when possible

    // Wrong
    char* blockOfMemory = (char* ) malloc(data.size());

    // Correct
    char *blockOfMemory = reinterpret_cast<char *>(malloc(data.size()));

• Do not put multiple statements on one line
• By extension, use a new line for the body of a control flow statement:

    // Wrong
    if (foo) bar();

    // Correct
    if (foo)
        bar();

Braces

• Use attached braces: The opening brace goes on the same line as the start of the statement. If the closing brace is followed by another keyword, it goes into the same line as well:

    // Wrong
    if (codec)
    {
    }
    else
    {
    }

    // Correct
    if (codec) {
    } else {
    }

• Exception: Function implementations and class declarations always have the left brace on the start of a line:

    static void foo(int g)
    {
        qDebug("foo: %i", g);
    }

    class Moo
    {
    };

Use curly braces only when the body of a conditional statement contains more than one line:

    // Wrong
    if (address.isEmpty()) {
        return false;
    }

    for (int i = 0; i < 10; ++i) {
        qDebug("%i", i);
    }

    // Correct
    if (address.isEmpty())
        return false;

    for (int i = 0; i < 10; ++i)
        qDebug("%i", i);

• Exception 1: Use braces also if the parent statement covers several lines / wraps:

    // Correct
    if (address.isEmpty() || !isValid()
        || !codec) {
        return false;
    }

• Exception 2: Brace symmetry: Use braces also in if-then-else blocks where either the if-code or the else-code covers several lines:

    // Wrong
    if (address.isEmpty())
        return false;
    else {
        qDebug("%s", qPrintable(address));
        ++it;
    }

    // Correct
    if (address.isEmpty()) {
        return false;
    } else {
        qDebug("%s", qPrintable(address));
        ++it;
    }

    // Wrong
    if (a)
        if (b)
            ...
        else
            ...

    // Correct
    if (a) {
        if (b)
            ...
        else
            ...
    }

• Use curly braces when the body of a conditional statement is empty

    // Wrong
    while (a);

    // Correct
    while (a) {}

Parentheses

• Use parentheses to group expressions:

    // Wrong
    if (a && b || c)

    // Correct
    if ((a && b) || c)

    // Wrong
    a + b & c

    // Correct
    (a + b) & c

Switch statements

• The case labels are in the same column as the switch
• Every case must have a break (or return) statement at the end or a comment to indicate that there's intentionally no break, unless another case follows immediately.

    switch (myEnum) {
    case Value1:
        doSomething();
        break;
    case Value2:
    case Value3:
        doSomethingElse();
        // fall through
    default:
        defaultHandling();
        break;
    }

Jump statements (break, continue, return, and goto)

• Do not put 'else' after jump statements:

    // Wrong
    if (thisOrThat)
        return;
    else
        somethingElse();

    // Correct
    if (thisOrThat)
        return;
    somethingElse();

• Exception: If the code is inherently symmetrical, use of 'else' is allowed to visualize that symmetry

Line breaks

• Keep lines shorter than 100 characters; wrap if necessary
• Commas go at the end of wrapped lines; operators start at the beginning of the new lines. An operator at the end of the lines is easy to miss if the editor is too narrow.

    // Wrong
    if (longExpression +
        otherLongExpression +
        otherOtherLongExpression) {
    }

    // Correct
    if (longExpression
        + otherLongExpression
        + otherOtherLongExpression) {
    }