Package org.python.core

Interface BufferProtocol

All Known Subinterfaces:
PyBuffer
All Known Implementing Classes:
Base1DBuffer, BaseArrayBuffer, BaseBuffer, BaseNIOBuffer, Py2kBuffer, PyArray, PyArrayDerived, PyByteArray, PyByteArrayDerived, PyMemoryView, PyShadowString, PyShadowStringDerived, PyString, PyStringDerived, PyUnicode, PyUnicodeDerived, SimpleBuffer, SimpleNIOBuffer, SimpleStringBuffer, SimpleWritableBuffer, Strided1DBuffer, Strided1DNIOBuffer, Strided1DWritableBuffer, SyspathArchive, ZeroByteBuffer
public interface BufferProtocol
Interface marking an object as capable of exposing its internal state as a PyBuffer.

A few objects implement BufferProtocol (e.g. by inheritance) but cannot actually provide their value as a PyBuffer. These should throw ClassCastException, permitting the idiom: 

     try (PyBuffer buf = ((BufferProtocol) obj).getBuffer(PyBUF.SIMPLE)) {
         ... // Do something with buf
     } catch (ClassCastException e) {
         ... // expected bytes object or buffer not obj.getType()
     }
The catch is executed identically whether the cause is the explicit cast of obj or getBuffer, and the try-with-resources releases the buffer if one was obtained.

  • Method Summary

    Modifier and Type
    Method
    Description
    PyBuffer
    getBuffer(int flags)
    Method by which the consumer requests the buffer from the exporter.

  • Method Details

    • getBuffer

      PyBuffer getBuffer(int flags) throws PyException, ClassCastException
      Method by which the consumer requests the buffer from the exporter. The consumer provides information on its ability to understand buffer navigation. Each consumer requesting a buffer in this way, when it has finished using it, should make a corresponding call to PyBuffer.release() on the buffer it obtained, or PyBuffer.close() using try-with-resources, since some objects alter their behaviour while buffers are exported.
      Parameters:
      flags - specifying features demanded and the navigational capabilities of the consumer
      Returns:
      exported buffer
      Throws:
      PyException - BufferError when expectations do not correspond with the buffer
      ClassCastException - when the object only formally implements BufferProtocol