Rosegarden Coding Style

Rosegarden house style is as follows, in approximately descending order of importance:

• Class names are UpperCamelCase, method names are lowerCamelCase, non-public member variables are m_prefixedCamelCase, slot names start with “slot”.

• Indentation is by four spaces at a time. There should be no tab characters anywhere in Rosegarden source code. The indentation should look the same regardless of whether you read it in an IDE, in a terminal window with “cat” or “vi”, in Emacs, or quoted in an email. It must not depend on having the right settings for tab-to-space conversion in your IDE when you read it. (Emacs and vim users will note that we already start every source file with a meta-comment that sets up the right indentation mode in these editors.)

• Use doxygen-style comments for class and function documentation

  /** ... */

  or

  ///

• No extra indentation inside namespaces; set off inner code by two carriage returns on either side of namespace brackets

namespace Rosegarden
{
// 1
// 2
class SomeUsefulClass
{
    //code
};
// 1
// 2
}

• Braces are what you might call Java-style, which means:

int
SomeClass::someMethod(int f)
{
   int result = 0;
   if (f >= 0) {
       for (int i = 0; i < f; ++i) {
           result += i;
       }
   } else {
       result = -1;
   }
   return result;
}

• Single statement blocks are preferably either “inline” or bracketed. Like this:

   if (something) somethingElse();
   else someOtherThing();
   if (something) {
       somethingElse();
   } else {
       someOtherThing();
   }

but not:

   if (something)
       somethingElse();

• Whitespace is much as in the above examples (outside but not inside (), after but not before ;, etc.):

    connect(detailsButton, SIGNAL(clicked(bool)), this, SLOT(slotDetails()));

but not:

    connect( detailsButton, SIGNAL( clicked(bool) ), this, SLOT( slotDetails() ) );

and please avoid:

    if( something)
    if(something)

No whitespace between if (and other C++ keywords) and the ( makes Michael's eyes hurt.

• Pointers are MyObject *ptr; not MyObject* ptr;

• If you have more arguments than will fit on a reasonable length line (80 characters is a good figure, but this is not a hard rule), align the extra arguments below and just after the opening ( rather than at a new level of indentation:

    connect(m_pluginList, SIGNAL(activated(int)),
            this, SLOT(slotPluginSelected(int)));

but not:

    connect(m_pluginList, SIGNAL(activated(int)),
        this, SLOT(slotPluginSelected(int)));

• If your ( is so far to the right that following the above rule isn't practical, then indent the remainder of the () block by 8 spaces.

        CommandHistory::getInstance()->addCommand(new SegmentSyncCommand(
                comp.getSegments(), selectedTrack,
                dialog.getTranspose(),
                dialog.getLowRange(),
                dialog.getHighRange(),
                clefIndexToClef(dialog.getClef())));

• Use comment codes in your comments when appropriate:

//!!!

//&&&

//@@@

//###

//$$$

• If in doubt, please err on the side of putting in too many comments. We have contributors of all ability levels working here, and what may seem obvious to you might be complete gibberish to someone else. Comments give everyone a better chance to be useful, and they are always welcome, while nobody will think you are a super code warrior or code gazelle for committing a thousand lines that have only three choice comments

• When commenting out a large block of text, it is preferable to use C++ style

  //

  comments instead of C-style

  /* */

  comments (except as applies to writing comments specific to doxygen.)

//&&& This code was deleted temporarily
//    for (int m = 0; m <= n; ++m) {
//        int x = s.x() + (int)((m * ((double)m * ax + bx)) / n);
//        int y = s.y() + (int)((m * ((double)m * ay + by)) / n);
//    }

but not:

//&&& This code was deleted temporarily
/*  for (int m = 0; m <= n; ++m) {
        int x = s.x() + (int)((m * ((double)m * ax + bx)) / n);
        int y = s.y() + (int)((m * ((double)m * ay + by)) / n);
    } */

(The reason C++-style comments are preferred is not arbitrary. C++-style comments are much more obvious when viewing diffs on the rosegarden-bugs list, because they force the entire block of text to be displayed, instead of only the starting and ending lines.)

• Includes should try to follow the following pattern:

#include "MyHeader.h"

#include "MyCousinClassHeader.h"
#include "MyOtherCousin.h"

#include "RosegardenHeader.h"
#include "base/SomeOtherHeader.h"

#include <QSomeClass>
#include <QSomeOtherClass>

#include <some_stl_class>
#include <some_other_stl_class>

• Switch statements are all over the place, and we need to pick one style and use it, so we'll call this a good switch statement:

    switch (hfix) {
 
    case NoteStyle::Normal:
    case NoteStyle::Reversed:
        if (params.m_stemGoesUp ^ (hfix == NoteStyle::Reversed)) {
            s0.setX(m_noteBodyWidth - stemThickness);
        } else {
            s0.setX(0);
        }
        break;
 
    case NoteStyle::Central:
        if (params.m_stemGoesUp ^ (hfix == NoteStyle::Reversed)) {
            s0.setX(m_noteBodyWidth / 2 + 1);
        } else {
            s0.setX(m_noteBodyWidth / 2);
        }
        break;
    }

and this a bad one (note particularly the switch( here, grrrrr!):

    switch(layoutMode) {
        case 0 :
            findAction("linear_mode")->setChecked(true);
            findAction("continuous_page_mode")->setChecked(false);
            findAction("multi_page_mode")->setChecked(false);
            slotLinearMode();
        break;
        case 1 :
            findAction("linear_mode")->setChecked(false);
            findAction("continuous_page_mode")->setChecked(true);
            findAction("multi_page_mode")->setChecked(false);
            slotContinuousPageMode();
        break;
        case 2 :
            findAction("linear_mode")->setChecked(false);
            findAction("continuous_page_mode")->setChecked(false);
            findAction("multi_page_mode")->setChecked(true);
            slotMultiPageMode();
        break;
    }

• You should feel encouraged to use variables to make the code easier to understand without a look at the header or the API docs. Good:

    int spacing = 3;
    bool useHoops = false;
 
    doSomething(spacing, useHoops);

avoid:

    doSomething(3, false);

Note that you should not feel like you have to take this to ridiculous extremes. Just bear it in mind, especially when it's something obscure enough you've just had to go look at the header or the API yourself to figure out what some static parameter was for.

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