The MStatus class does not exist in the Maya .NET API. Functions that return an MStatus in C++ have been converted to void functions or return a boolean in C# to indicate special cases to Maya; for example, if Maya is expected to do processing in place of the plug-in. In the .NET API, these functions return true in place of MStatus.kSuccess and false otherwise.

The following function returns false instead of MStatus.kFailure:

• MPxCacheFormat::isValid()

The following functions return false instead of MStatus.kUnknownParameter:

• MPxNode::compute()
• MPxNode::legalConnection()
• MPxNode::legalDisconnection()
• MPxNode::connectionMade()
• MPxNode::connectionBroken()
• MPxNode::shouldSave()
• MPxFluidEmitterNode::fluidEmitter()
• MPxControlCommand::doEditFlags()
• MPxControlCommand::doQueryFlags()
• MPxManipContainer::doPress()
• MPxManipContainer::doDrag()
• MPxManipContainer::doRelease()
• MPxManipulatorNode::doPress()
• MPxManipulatorNode::doDrag()
• MPxManipulatorNode::doRelease()
• MPxManipulatorNode::doMove()
• MPxModelEditorCommand::doEditFlags()
• MPxModelEditorCommand::doQueryFlags()
• all virtual functions in MPxConstraintCommand except for appendSyntax()

The following functions return false instead of MStatus.kNotImplemented:

• MPxHardwareShader::getAvailableImages()
• MPxHardwareShader::renderImage()
• MPxHardwareShader::renderSwatchImage()
• MPxHwShaderNode::getAvailableImages()
• MPxHwShaderNode::renderImage() 4 args
• MPxHwShaderNode::renderImage() 5 args
• MPxHwShaderNode::renderSwatchImage()

The following function returns false instead of MStatus.kNotFound

• MPxGlBuffer::open()

This behavior also applies to the Maya functions that a plug-in calls. For instance, a function that in C++ returns kFailure in case of a failure instead throws an exception of type ApplicationException in C#. The following are the possible types of exceptions:

• ApplicationException (instead of kFailure or kLicenseFailure)
• InsufficientMemoryException (instead of kInsufficientMemory)
• ArgumentException (instead of kInvalidParameter)
• ArgumentNullException (instead of kInvalidParameter when the parameter is null)
• ArgumentOutOfRangeException (instead of kInvalidParameter when the parameter is not in the expected range)

When Maya calls a function of your plug-in (for example, the virtual method doIt() of a MPxCommand derived class), it always wraps the call with a try-catch clause. When it catches an exception thrown either by your function or by a Maya function that your function calls, a message box appears and displays the details of the exception, including the callstack, which may be very useful for debugging.