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|
**************
C++11 bindings
**************
.. role:: cpp(code)
:language: c++
:class: highlight
.. caution::
DO NOT use the clause ``using namespace adios2`` in your code.
This is in general a bad practices that creates potential name conflicts.
Always use ``adios2::`` explicitly, *e.g.* ``adios2::ADIOS``, ``adios2::IO``.
.. tip::
Prefer the C++11 bindings to take advantage of added functionality (*e.g.* move semantics, lambdas, etc.). If you must use an older C++ standard (98 or 03) to avoid application binary interface (ABI) incompatibilities use the C bindings.
ADIOS2 components classes
-------------------------
ADIOS2 C++ bindings objects are mapped 1-to-1 to the ADIOS components described in the :ref:`Components Overview` section.
Only the ``adios2::ADIOS`` object is "owned" by the developer's program using adios2, all other components are light-weight objects that point internally to a component that lives inside the ``adios2::ADIOS`` "factory" object.
.. code-block:: c++
c++11
adios2::ADIOS
adios2::IO
adios2::Variable<T>
adios2::Attribute<T>
adios2::Engine
adios2::Operator
The following section provides a summary of the available functionality for each class.
:ref:`ADIOS` class
------------------
.. doxygenclass:: adios2::ADIOS
:project: CXX11
:path: ../../bindings/CXX11/adios2/cxx11/
:members:
:ref:`IO` class
---------------
.. doxygenclass:: adios2::IO
:project: CXX11
:path: ../../bindings/CXX11/adios2/cxx11/
:members:
:ref:`Variable` ``<T>`` class
-----------------------------
.. doxygenclass:: adios2::Variable
:project: CXX11
:path: ../../bindings/CXX11/adios2/cxx11/
:members:
:ref:`Attribute` ``<T>`` class
------------------------------
.. doxygenclass:: adios2::Attribute
:project: CXX11
:path: ../../bindings/CXX11/adios2/cxx11/
:members:
.. _C++11 Engine class:
:ref:`Engine` class
-------------------
.. doxygenclass:: adios2::Engine
:project: CXX11
:path: ../../bindings/CXX11/adios2/cxx11/
:members:
:ref:`Operator` class
---------------------
.. doxygenclass:: adios2::Operator
:project: CXX11
:path: ../../bindings/CXX11/adios2/cxx11/
:members:
**Debugging**
For debugging, ADIOS2 C++11 class instances and enums can be passed directly to ostreams,
as well as converted to human-readable strings via the ubiquitous ``ToString(object)`` member variable.
You can also directly pass objects to an ``ostream``.
Example:
.. code-block:: c++
auto myVar = io.DefineVariable<double>("myVar");
std::cout << myVar << " has shape id " << myVar.ShapeID() << std::endl;
// will print:
// Variable<double>(Name: "myVar") has shape id ShapeID::GlobalValue
if (myVar.ShapeID() != adios2::ShapeID::GlobalArray)
{
throw std::invalid_argument("can't handle " +
ToString(myVar.ShapeID()) + " in " +
ToString(myVar));
}
// will throw exception like this:
// C++ exception with description "can't handle ShapeID::GlobalValue
// in Variable<double>(Name: "myVar")" thrown
**Group API**
.. doxygenclass:: adios2::Group
:project: CXX11
:path: ../../bindings/CXX11/adios2/cxx11/
:members:
The Group API can be used for inquiring other group objects, variables, and attributes
by reading, provided that variable and attribute names were written in a tree-like
way similar that is used in a file system:
.. code-block:: bash
"group1/group2/group3/variable1"
"group1/group2/group3/attribute1"
A group object containing the tree structure is obtained by the
``InquireGroup`` function of the ``IO`` object.
.. code-block:: c++
Group g = io.InquireGroup("group1");
Another group object can be generated by the predecessor group object.
.. code-block:: c++
Group g1 = g.InquireGroup("group2");
The absolute path can be inquired or set explicitly
.. code-block:: c++
std::string path = g.InquirePath();
g.setPath("group1/group2/group3");
Names of available groups, variables and attributes could be inquired:
.. code-block:: c++
std::vector<std::string> groups = g.AvailableGroups();
std::vector<std::string> variables = g.AvailableVariables();
std::vector<std::string> attributes = g.AvailableVariables();
Finally, variables can be inquired
.. code-block:: c++
auto var = g.InquireVariable("variable1");
An extra function is provided that returns a type of a variable
.. code-block:: c++
DataType varType = g.VariableType("variable1");
**Step selection**
Steps for reading can be selected using a pre-set parameter with as a file name
as a key and a list of selected steps separated by comma as a value.
.. code-block:: c++
io.SetParameter(filename, "1,3");
|
