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/**
@page conventions_cpp C++ API Conventions
@section classes_vs_structs Classes vs. Structs
In general, classes are preferred, along with getX() / setX() methods.
This allows extending the API in the future without breaking compatibility.
In cases of "super-primitives" (like @ref openni::RGB888Pixel), structs are used.
@section return_values Return Values from Methods
- All getters return the value as their return value, and cannot fail, for example: @ref openni::VideoFrameRef::getWidth().
If the value is a complex type, it will be returned as const reference, for example: @ref openni::Device::getDeviceInfo().
If a specific property doesn't exist for the specific object, a meaningful value will be returned.
- stop / destroy / close methods does not have return values, for example: @ref openni::Device::close().
- All other methods return @ref openni::Status, for example: @ref openni::VideoStream::create().
@section pointers_and_refs Arguments to Methods
- Output arguments, as well as in/out arguments are always passed as a pointer, for example: @ref openni::VideoStream::readFrame().
- Input arguments:
- Primitives are passed by value, for example: @ref openni::VideoMode::setPixelFormat().
- Complex types are passed as const reference, for example: @ref openni::VideoStream::create().
- In the rare cases where the object identity matters, and not it's content, it will be passed as a pointer, for example: @ref openni::OpenNI::addListener().
@section object_lifetime Object Lifetime
Some objects have their lifetime goverened by the user. For example, a @ref openni::VideoStream is created using the @ref openni::VideoStream::create "create()" method
and destroyed by calling @ref openni::VideoStream::destroy "destroy()". In those cases, it is important that they get destroyed in the right order. For example, if
you create a @ref openni::VideoStream on a specific @ref openni::Device, don't close the device before destroying that video stream. In the same manner, all @ref openni::VideoFrameRef
objects should be released before destroying the stream, and <b>all</b> OpenNI objects should be destroyed before calling @ref openni::OpenNI::shutdown().
Other objects are not created by the user, but are actually members of other objects. For example, calling @ref openni::Device::getDeviceInfo() returns a reference
to a @ref openni::DeviceInfo object. Note that once the @ref openni::Device object that was used gets closed, the @ref openni::DeviceInfo reference is no longer valid. Do
not try to use it to access methods of the @ref openni::DeviceInfo object.
@section arrays Arrays
Some methods return an array of items. We created a very simple template class, @ref openni::Array, which only holds the pointer to the underlying C array
and the number of elements in that array. Once the array has been released, the elements are no longer accessible. Do not keep a pointer to a specific
item in the array and use it after releasing it.
@section properties_and_commands Properties and Commands
OpenNI has a mechanism for generic properties and commands, both for devices and for streams. Commands are used by calling @ref openni::Device::invoke() or
@ref openni::VideoStream::invoke() and Properties can be read via @ref openni::Device::getProperty() and @ref openni::VideoStream::getProperty() and written via
@ref openni::Device::setProperty() and @ref openni::VideoStream::setProperty().
Though both might use both primitives and complex types, generally, properties are used to encapsulate a logical data unit (even though complex) while commands are used in the following cases:
- The action requires some arguments (that are not part of the data unit).
- Obtaining a data unit via getProperty() have side effects.
- The operation is expensive enough that you want to communicate it to the user.
- The action has side effects.
- The data unit might be changed over time without an outside request.
*/
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