Release 7.0 (XYZ 2017)



The following utility classes will be removed in 8.0:


Release 6.0 (Aug. 2016)

Release 5.0 (Sep. 2015)

The main changes since release 4.0 are:

Deprecated getXXXField methods have been removed from PVStructure

The following methods have been removed from PVStructure

Use template getSubField instead, e.g. use

getSubField< PVInt >(fieldName)

in place of


Convert copy methods and equals operators

Convert copy methods where moved and replaced with methods on PVField classes, i.e.

PVField::copy(const PVField& from)


PVField::copyUnchecked(const PVField& from)

were added to allow unchecked copies, to gain performance where checked are not needed (anymore).

In addition: - isCompatibleXXX methods were removed in favour of Field::operator==. - equals methods were remove in favour of PVField::operator==. - operator== methods where moved to pvIntrospect.h and pvData.h


Before this method, depending on types for to and from, sometimes did a shallow copy, i.e. just made to shared_ptr for to share the same data as from. Now it always copies between the subfield of to and from.

New method getSubFieldT, like getSubField except it throws an exception

PVStructure has a new template member

getSubFieldT(std::string const &fieldName)

that is like getSubField except that it throws a runtime_error instead of returning null.

findSubField method removed from PVStructure

This was mainly used in the implementation of getSubField. With a change to the latter, findSubField was removed.

New stream operators

New steam operators are available for Field and PVField. Before to print a Field (or any extension) or a PVField (or any extension) it was necessary to have code like:

 void print(StructureConstPtr struc, PVStructurePtr pv)
     if(struc) {
         cout << *struc << endl;
     } else {
         cout << "nullptr\n"
     if(pv) {
         cout << *.struc << endl;
     } else {
         cout << "nullptr\n"

Now it can be done as follows:

 void print(StructureConstPtr struc, PVStructurePtr pv)
     cout << struc << endl;
     cout << pv << endl;

New template version of Structure::getField

A new template getField method has been added to Structure


Can be used, for example, as follows:

StructurePtr tsStruc = struc->getField<Structure>("timeStamp");

Fixes for static initialisation order issues

Certain static builds (in particular Windows builds) of applications using pvData had issues due to PVStructure::DEFAULT_ID being used before being initialised. This has been fixed.

CreateRequest change

createRequest could cause a SEGFAULT if passed a bad argument. This has been changed so the it returns a null pvStructure and provides an error.

Release 4.0

The main changes since release 3.0.2 are:

New Semantics for Arrays

PVScalarArray, PVStructureArray, and PVUnionArray all enforce COW (Copy On Write) Semantics. In order to limit memory usage the storage for raw data is managed via a new sharedvector facility. This allows multiple instances of array data to use the shared raw data. COW is implemented via sharedvectors of const data, i. e. data that can not be modified.

String no longer defined

This is replaced by std::string.

timeStamp and valueAlarm name changes

In timeStamp nanoSeconds is changed to nanoseconds.

In valueAlarm hysteresis is changed to hysteresis

toString replaced by stream I/O

pvData.h and pvIntrospect no longer defines toString Instead they have stream support. pvIntrospect uses method dump and pvData uses dumpValue. For example:

  PVDoublePtr pvValue;
  String buffer;
  cout << buffer << endl;
  cout << buffer << evdl;

is replaced by

  PVDoublePtr pvValue;
  cout << *pvValue << endl
  cout << *pvValue->getField() << endl;

union is a new basic type.

There are two new basic types: union_t and unionArray.

A union is like a structure that has a single subfield. There are two flavors:

The field type can be dynamically changed.


This consists of createRequest and pvCopy. createRequest was moved from pvAccess to here. pvCopy is moved from pvDatabaseCPP and now depends only on pvData, i.e. it no longer has any knowledge of PVRecord.


This is for is for use by code that implements pvAccess monitors. This is prototype and is subject to debate.

Release 3.0.2

This was the starting point for RELEASE_NOTES