org.python.core

## Class PyMemoryView

- java.lang.Object
- - org.python.core.PyObject
  - - org.python.core.PySequence
    - - org.python.core.PyMemoryView

All Implemented Interfaces:
  java.io.Serializable, BufferProtocol, Traverseproc

    public class PyMemoryView
    extends PySequence
    implements BufferProtocol, Traverseproc

Class implementing the Python `memoryview` type. It provides a wrapper around the Jython buffer API.

See Also:
  Serialized Form

### Nested Class Summary

### Nested classes/interfaces inherited from class org.python.core.PyObject

`PyObject.ConversionException`

### Field Summary

Fields
`static PyType` `TYPE`

### Fields inherited from class org.python.core.PyObject

`gcMonitorGlobal`

### Constructor Summary

Constructors
Constructor and Description
`PyMemoryView(BufferProtocol pybuf)` Construct a `PyMemoryView` from an object bearing the `BufferProtocol` interface.

### Method Summary

All Methods Instance Methods Concrete Methods
`PyObject` `__enter__()` Called at the start of a context-managed suite (supporting the `with` clause).
`PyObject` `__eq__(PyObject other)` Equivalent to the standard Python __eq__ method.
`boolean` `__exit__(PyObject type, PyObject value, PyObject traceback)` Called at the end of a context-managed suite (supporting the `with` clause), and will release the `memoryview`.
`PyObject` `__ge__(PyObject other)` Equivalent to the standard Python __ge__ method.
`PyObject` `__gt__(PyObject other)` Equivalent to the standard Python __gt__ method.
`PyObject` `__le__(PyObject other)` Equivalent to the standard Python __le__ method.
`int` `__len__()` Equivalent to the standard Python __len__ method.
`PyObject` `__lt__(PyObject other)` Equivalent to the standard Python __lt__ method.
`PyObject` `__ne__(PyObject other)` Equivalent to the standard Python __ne__ method.
`java.lang.Object` `__tojava__(java.lang.Class<?> c)` Equivalent to the Jython __tojava__ method.
`java.lang.String` `format()`
`PyBuffer` `getBuffer(int flags)` Method by which the consumer requests the buffer from the exporter.
`int` `hashCode()`
`int` `itemsize()`
`void` `memoryview_release()`
`int` `ndim()`
`PyObject` `obj()`
`void` `pyset(int index, PyObject value)` Sets the indexed element of the memoryview to the given value, treating the operation as assignment to a slice of length one.
`boolean` `readonly()`
`boolean` `refersDirectlyTo(PyObject ob)` Optional operation.
`void` `release()` Request a release of the underlying buffer exposed by the `memoryview` object.
`PyObject` `shape()`
`PyObject` `strides()`
`PyObject` `suboffsets()`
`PyString` `tobytes()` Implementation of Python `tobytes()`.
`PyList` `tolist()` Implementation of Python `tolist()`.
`int` `traverse(Visitproc visit, java.lang.Object arg)` Traverses all directly contained `PyObject`s.

### Methods inherited from class org.python.core.PySequence

`__delitem__, __delslice__, __finditem__, __finditem__, __getitem__, __getslice__, __iter__, __nonzero__, __setitem__, __setitem__, __setslice__, isMappingType, isNumberType, isSequenceType`

### Methods inherited from class org.python.core.PyObject

`__abs__, __add__, __and__, __call__, __call__, __call__, __call__, __call__, __call__, __call__, __call__, __call__, __call__, __call__, __call__, __call__, __call__, __call__, __call__, __cmp__, __coerce__, __coerce_ex__, __complex__, __contains__, __delattr__, __delattr__, __delete__, __delitem__, __delslice__, __dir__, __div__, __divmod__, __ensure_finalizer__, __findattr__, __findattr__, __findattr_ex__, __finditem__, __float__, __floordiv__, __format__, __get__, __getattr__, __getattr__, __getitem__, __getnewargs__, __getslice__, __hash__, __hex__, __iadd__, __iand__, __idiv__, __idivmod__, __ifloordiv__, __ilshift__, __imod__, __imul__, __index__, __int__, __invert__, __ior__, __ipow__, __irshift__, __isub__, __iternext__, __itruediv__, __ixor__, __long__, __lshift__, __mod__, __mul__, __neg__, __not__, __oct__, __or__, __pos__, __pow__, __pow__, __radd__, __rand__, __rdiv__, __rdivmod__, __reduce__, __reduce_ex__, __reduce_ex__, __repr__, __rfloordiv__, __rlshift__, __rmod__, __rmul__, __ror__, __rpow__, __rrshift__, __rshift__, __rsub__, __rtruediv__, __rxor__, __set__, __setattr__, __setattr__, __setitem__, __setslice__, __str__, __sub__, __truediv__, __trunc__, __unicode__, __xor__, _add, _and, _callextra, _cmp, _div, _divmod, _doget, _doget, _doset, _eq, _floordiv, _ge, _gt, _iadd, _iand, _idiv, _idivmod, _ifloordiv, _ilshift, _imod, _imul, _in, _ior, _ipow, _irshift, _is, _isnot, _isub, _itruediv, _ixor, _jcall, _jcallexc, _jthrow, _le, _lshift, _lt, _mod, _mul, _ne, _notin, _or, _pow, _rshift, _sub, _truediv, _xor, asDouble, asIndex, asIndex, asInt, asInt, asIterable, asLong, asLong, asName, asName, asString, asString, asStringOrNull, asStringOrNull, bit_length, conjugate, delDict, delType, dispatch__init__, equals, fastGetClass, fastGetDict, getDict, getType, implementsDescrDelete, implementsDescrGet, implementsDescrSet, invoke, invoke, invoke, invoke, invoke, invoke, isCallable, isDataDescr, isIndex, isInteger, noAttributeError, object___subclasshook__, readonlyAttributeError, setDict, setType, toString`

### Methods inherited from class java.lang.Object

`getClass, notify, notifyAll, wait, wait, wait`

### Field Detail

#### TYPE

    public static final PyType TYPE

### Constructor Detail

#### PyMemoryView

    public PyMemoryView(BufferProtocol pybuf)
                 throws java.lang.ClassCastException

Construct a `PyMemoryView` from an object bearing the `BufferProtocol` interface. If this object is already an exported buffer, the `memoryview` takes a new lease on it. The buffer so obtained will be writable if the underlying object permits it.

Parameters:
  `pybuf` - buffer exported by some underlying object
Throws:
  `java.lang.ClassCastException` - in cases where `pybuf.getBuffer` does so.

### Method Detail

#### __tojava__

    public java.lang.Object __tojava__(java.lang.Class<?> c)

Description copied from class: `PyObject`
Equivalent to the Jython __tojava__ method. Tries to coerce this object to an instance of the requested Java class. Returns the special object `Py.NoConversion` if this `PyObject` can not be converted to the desired Java class.

Overrides:
  `__tojava__` in class `PySequence`
Parameters:
  `c` - the Class to convert this `PyObject` to.

#### obj

    public PyObject obj()

#### format

    public java.lang.String format()

#### itemsize

    public int itemsize()

#### shape

    public PyObject shape()

#### ndim

    public int ndim()

#### strides

    public PyObject strides()

#### suboffsets

    public PyObject suboffsets()

#### readonly

    public boolean readonly()

#### tobytes

    public PyString tobytes()

Implementation of Python `tobytes()`. Return the data in the buffer as a byte string (an object of class `str`).

Returns:
  byte string of buffer contents.

#### tolist

    public PyList tolist()

Implementation of Python `tolist()`. Return the data in the buffer as a `list` where the elements are an appropriate type (`int` in the case of a byte-oriented buffer, which is the only case presently supported).

Returns:
  a list of buffer contents.

#### __len__

    public int __len__()

Description copied from class: `PyObject`
Equivalent to the standard Python __len__ method. Part of the mapping discipline.

Overrides:
  `__len__` in class `PyObject`
Returns:
  the length of the object

#### hashCode

    public int hashCode()

Overrides:
  `hashCode` in class `PyObject`

#### __eq__

    public PyObject __eq__(PyObject other)

Description copied from class: `PyObject`
Equivalent to the standard Python __eq__ method.

Overrides:
  `__eq__` in class `PySequence`
Parameters:
  `other` - the object to compare this with.
Returns:
  the result of the comparison.

#### __ne__

    public PyObject __ne__(PyObject other)

Description copied from class: `PyObject`
Equivalent to the standard Python __ne__ method.

Overrides:
  `__ne__` in class `PySequence`
Parameters:
  `other` - the object to compare this with.
Returns:
  the result of the comparison.

#### __lt__

    public PyObject __lt__(PyObject other)

Description copied from class: `PyObject`
Equivalent to the standard Python __lt__ method.

Overrides:
  `__lt__` in class `PySequence`
Parameters:
  `other` - the object to compare this with.
Returns:
  the result of the comparison.

#### __le__

    public PyObject __le__(PyObject other)

Description copied from class: `PyObject`
Equivalent to the standard Python __le__ method.

Overrides:
  `__le__` in class `PySequence`
Parameters:
  `other` - the object to compare this with.
Returns:
  the result of the comparison.

#### __ge__

    public PyObject __ge__(PyObject other)

Description copied from class: `PyObject`
Equivalent to the standard Python __ge__ method.

Overrides:
  `__ge__` in class `PySequence`
Parameters:
  `other` - the object to compare this with.
Returns:
  the result of the comparison.

#### __gt__

    public PyObject __gt__(PyObject other)

Description copied from class: `PyObject`
Equivalent to the standard Python __gt__ method.

Overrides:
  `__gt__` in class `PySequence`
Parameters:
  `other` - the object to compare this with.
Returns:
  the result of the comparison.

#### __enter__

    public PyObject __enter__()

Called at the start of a context-managed suite (supporting the `with` clause).

Returns:
  this object

#### __exit__

    public boolean __exit__(PyObject type,
                            PyObject value,
                            PyObject traceback)

Called at the end of a context-managed suite (supporting the `with` clause), and will release the `memoryview`.

Returns:
  false

#### getBuffer

    public PyBuffer getBuffer(int flags)

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.

The `PyBuffer` returned from this method is just the one on which the `memoryview` was first constructed. The Jython buffer API is such that sharing directly is safe (as long as the get-release discipline is observed).

Specified by:
  `getBuffer` in interface `BufferProtocol`
Parameters:
  `flags` - specifying features demanded and the navigational capabilities of the consumer
Returns:
  exported buffer

#### release

    public void release()

Request a release of the underlying buffer exposed by the `memoryview` object. Many objects take special actions when a view is held on them (for example, a `bytearray` would temporarily forbid resizing); therefore, calling `release()` is handy to remove these restrictions (and free any dangling resources) as soon as possible.

After this method has been called, any further operation on the view raises a `ValueError` (except `release()` itself which can be called multiple times with the same effect as just one call).

This becomes an exposed method in CPython from 3.2. The Jython implementation of `memoryview` follows the Python 3.3 design internally and therefore safely anticipates Python 3 in exposing `memoryview.release` along with the related context-management behaviour.

#### memoryview_release

    public final void memoryview_release()

#### pyset

    public void pyset(int index,
                      PyObject value)
               throws PyException

Sets the indexed element of the memoryview to the given value, treating the operation as assignment to a slice of length one. This is different from the same operation on a byte array, where the assigned value must be an int: here it must have the buffer API and length one. This is an extension point called by PySequence in its implementation of `PySequence.__setitem__(int, org.python.core.PyObject)` It is guaranteed by PySequence that the index is within the bounds of the memoryview. Any other clients calling `pyset(int, PyObject)` must make the same guarantee.

Parameters:
  `index` - index of the element to set.
  `value` - to set this element to, regarded as a buffer of length one unit.
Throws:
  `PyException` - `AttributeError` if value cannot be converted to an integer
  `PyException` - `ValueError` if value<0 or value>255

#### traverse

    public int traverse(Visitproc visit,
                        java.lang.Object arg)

Description copied from interface: `Traverseproc`
Traverses all directly contained `PyObject`s. Like in CPython, `arg` must be passed unmodified to `visit` as its second parameter. If `Visitproc.visit(PyObject, Object)` returns nonzero, this return value must be returned immediately by traverse. `Visitproc.visit(PyObject, Object)` must not be called with a `null` PyObject-argument.

Specified by:
  `traverse` in interface `Traverseproc`

#### refersDirectlyTo

    public boolean refersDirectlyTo(PyObject ob)

Description copied from interface: `Traverseproc`
Optional operation. Should only be implemented if it is more efficient than calling `Traverseproc.traverse(Visitproc, Object)` with a visitproc that just watches out for `ob`. Must return `false` if `ob` is `null`.

Specified by:
  `refersDirectlyTo` in interface `Traverseproc`