*****************
From v4.1 to v4.2
*****************

.. highlight:: c++


Summary
=======


Stream methods
--------------

The :cpp:func:`Stream::readBytes` has been virtualised and overridden for :cpp:class:`IDataSourceStream`
descendents for more efficient operation, especially with ArduinoJson.
For normal read operations where the stream position is to be updated, applications should use
this method in preference to :cpp:func:`IDataSourceStream::readMemoryBlock`.

An addition method :cpp:func:`IDataSourceStream::moveString` has been added to support extracting
the content of a memory-based stream into a String object without duplicating the data.
This is supported by :cpp:class:`LimitedMemoryStream` and :cpp:class:`MemoryDataStream`.

Stream / file seeking
---------------------

To provide a consistent interface :cpp:type:`SeekOrigin` is now used with all *seek* methods for streams,
and also by file system functions. Mappings are::

   SeekOrigin::Start instead of eSO_FileStart
   SeekOrigin::Current instead of eSO_CurrentPos
   SeekOrigin::End instead of eSO_FileEnd
 
These map to the standard C *SEEK_SET*, *SEEK_CUR* and *SEEK_END* but as SeekOrigin is strongly typed
it offers compile-time checking, and has a ``toString(SeekOrigin)`` overload.


getBody methods
---------------

The :cpp:func:`HttpRequest::getBody` and :cpp:func:`HttpResponse::getBody` methods have been revised to use
move semantics. Previously, the data was copied into a new String which effectively doubled memory usage.

If you have set a non-memory stream type (e.g. :cpp:class:`FileStream`) which does not implement :cpp:func:`IDataSourceStream::moveString()`
then an invalid String will be returned. In this situation you should use :cpp:func:`HttpResponse::getBodyStream` instead.


ContentType / MIME types
------------------------

:cpp:func:`String toString(MimeType)` has been moved out of the ``ContentType`` namespace,
so no longer requires the ``ContentType::`` qualifier.