Difference between revisions of "Documentation/Nightly/Developers/Style Guide"

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= Code style =
| text  = [https://slicer.readthedocs.io/en/latest/developer_guide/style_guide.html This page has been moved to read-the-docs.]
'''Code that inherits from VTK classes should follow VTK coding conventions for naming, indentation, etc.''' See http://www.vtk.org/Wiki/VTK_Coding_Standards for details.
| background-color = 8FBC8F }}
== Naming ==
# Acronyms should be written with the same case for each letter (all uppercase or all lowercase).
#: ''RASToSlice'' not ''RasToSlice''
#: ''vtkMRML'' not ''vtkMrml''
#: ''vtkSlicer'' not ''vTKSlicer''
# Words should be spelled out and not abreviated
#: ''GetWindow'' not ''GetWin''
# File names must follow the [http://en.wikipedia.org/wiki/CamelCase Camel case] convention
#: ''TestMyFeature.cxx'' not ''Test-My_Feature.cxx''
== Comments ==
# include extensive comments in the header files
# keep the comments up to date as the code changes
# use the keyword TODO to flag spots in the code that need to be revisited
# do not leave blocks of commented out code in the source file -- if needed insert links to prior svn versions as comments
== Functions ==
# Don't mix different levels of abstraction
#: Examples:
#:: When dealing with files names and path, use [http://vtk.org/gitweb?p=VTK.git;a=blob;f=Utilities/KWSys/vtksys/SystemTools.hxx.in;h=04f197842695c5914d1a49d4738159d3bccb08e8;hb=HEAD kwsys::SystemTools] in VTK classes, [http://doc.qt.nokia.com/{{documentation/{{documentation/version}}/qtversion}}/qfileinfo.html QFileInfo]/[http://doc.qt.nokia.com/{{documentation/{{documentation/version}}/qtversion}}/qdir.html QDir] in Qt classes or [http://docs.python.org/library/os.path.html os.path] in python. Instead of doing string manipulation manually:
#:::<code>QString filePath = directoryPath + "/" + fileName + ".exe"</code>)
#:: prefer instead:
#:::<code>SystemTools::JoinPath(), SystemTools::GetFilenameName()...</code>
#:::<code>QFileInfo(QDir directory, QString fileName), QFileInfo::suffix(), QFileInfo::absoluteFilePath()...</code>
#:::<code>os.path.join(), os.path.splitext(), os.path.abspath()...</code>
#: References:
#:* [http://www.amazon.com/gp/product/0132350882?ie=UTF8&tag=solisyntprog-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0132350882 Clean Code] from ''Robert C. Martin'': ''Mixing levels of abstraction within a function is always confusing. Readers may not be able to tell whether a particular expression is an essential concept or a detail. Worse, like broken windows, once details are mixed with essential concepts, more and more details tend to accrete within the functions.''
#:* http://zuskin.com/coding_habits__functions.htm#Abstraction_levels
# Use STL where you can, but follow the VTK [http://www.vtk.org/Wiki/VTK_FAQ#Can_I_use_STL_with_VTK.3F guidelines]
## However, prefer [http://doc.qt.nokia.com/{{documentation/{{documentation/version}}/qtversion}}/containers.html Qt Container classes] to STL classes in Qt files
## Note that a [http://www.vtk.org/doc/nightly/html/classvtkCollection.html vtkCollection] is somewhat equivalent to <code>std::list<vtkSmartPointer<vtkObject*> ></code>
== Language Specific ==
# [[Documentation/{{documentation/version}}/Developers/Style Guide/Cpp | C++]]
# [[Documentation/{{documentation/version}}/Developers/Style Guide/Python | Python]]
# [[Documentation/{{documentation/version}}/Developers/Style Guide/CMake | CMake]]
== Library Dependencies ==
# MRML classes should only depend on vtk and itk (not Slicer Logic or Qt)
# Logic classes depend on MRML to store state
# Logic classes should encapsulate vtk and itk pipelines to accomplish specific slicer tasks (such as resampling volumes for display)
# GUI classes can depend on MRML and Logic and Qt
== Development Practices ==
# While developing code, enable VTK_DEBUG_LEAKS (ON by default) in your vtk build and be sure to clean up any leaks that arise from your contributions.
== Coordinate Systems ==
# World space for 3D Views is in RAS (Right Anterior Superior) space. See [[Coordinate systems]].
# All units are expressed in Millimeters (mm)
== Misc. ==
= Commits =
#Prefix the commit message title with "BUG:","ENH:","COMP:", "STYLE:". Note the ':' (colon) character.
#Explain in the commit message title the "impact of the commit to the user"
#Add in the commit message body the Mantis issue number prefixed by '#' (pound) character.
==Commit message prefix==
Subversion Commits to Slicer require commit type in the comment.
Valid commit types are:
  BUG:  - a change made to fix a runtime issue
            (crash, segmentation fault, exception, or incorrect result,
  COMP:  - a fix for a compilation issue, error or warning,
  ENH:  - new functionality added to the project,
  PERF:  - a performance improvement,
  STYLE: - a change that does not impact the logic or execution of the code.
            (improve coding style, comments, documentation).
Note that the ':'(colon) directly follows the commit tag. For example, it is: "STYLE:" not "STYLE :"
The Subversion command to commit the change is:
  svn commit -m "BUG: fixed core dump when passed float data" filename1[, filename2, ...]
By using the <code>-m</code> command line option, it's not possible to submit a message having multiple line.
Submitting a mutli-line message can be achieved using the <code>-f</code> option:
  svn commit -f /path/to/message filename1[, filename2, ...]
It's also possible to set the environment variable [http://www.google.com/search?q=SVN_EDITOR|<code>SVN_EDITOR</code>]
==Message content==
A good commit message title (first line) should '''explain what the commit does for the user, not ''how'' it is done'''. ''How'' can be explained in the body of the commit message (if looking at the code of the commit is not self explanatory enough).
*Bad: <code>BUG: Check pointer validity before dereferencing</code> -> ''implementation detail'', ''self-explanatory'' (by looking at the code)
*Good: <code>BUG: Fix crash in Module X when clicking Apply button</code>
*Bad: <code>ENH: More work in qSlicerXModuleWidget</code> -> <code>more work</code> is ''too vague'', <code>qSlicerXModuleWidget</code> is too ''low level''
*Good: <code>ENH: Add float image outputs in module X</code>
*Bad: <code>COMP: Typo in cmake variable</code> -> ''implementation detail'', ''self-explanatory''
*Good: <code>COMP: Fix compilation error with Numpy on Visual Studio</code>
If the commit is related to a [http://na-mic.org/Mantis/view_all_bug_page.php mantis issue] (bug or feature request), you can mention it in the commit message body by preceding the issue number with a '''#'''(pound) character:
BUG: Fix crash in Volume Rendering module when switching view layout
vtkSetAndObserveMRMLNodeEventsMacro can't be used for observing all types of vtkObjects,
only vtkMRMLNode is expected by vtkMRMLAbstractLogic::OnMRMLNodeModified(...)
Closes #1641
Where <code>1641</code> refers to the [http://www.na-mic.org/Bug/view.php?id=1641 issue number] in mantis
Notice the empty 2nd line.
==Importing changes from external project/repository==
When you update the git tag or svn revision of any external project, explicit in the commit message what the update does instead of just mentioning that an update in made.
This will avoid having a Slicer commit history made of ineligible messages:
r19180 - ENH: Update git tag
r19181 - BUG: Update svn revision
r19182 - ENH: revision updated
Ideally it should be the same message than the commit(s) in the external repository.
<code>ENH: Add feature A in module X</code> instead of <code>ENH: Update git tag</code>
== Resources ==
= UI Design Guidelines =
{{:Documentation/{{documentation/version}}/Developers/Style Guide/UI}}

Latest revision as of 20:32, 15 March 2022

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