Changes planned in Qgate 0.3
============================

Script API changes
------------------

Some functions in qgate.script API will be renamed.

- The first letters of some function names are capitalized.
- An operator, release_qreg() is renamed to RelaseQreg().

============ =============
0.1, 0.2.x   0.3 and above
============ =============
ctrl         Ctrl
measure      Measure
prob         Prob
if\_         If
barrier      Barrier
reset        Reset
============ =============

One can use updated API with Qgate 0.2.1 or later by importing qgate.script.script2.*

.. code-block:: python

    # to use script API from 0.3.
    import qgate.script.script2.*


Source code updater is included in 0.2.1 as a module, qgate.tools.update_script.  Below is example usages.

.. code-block:: bash

   # update.  Original source files are saved as *.py.org
   $ python -m qgate.tools.update_script file1.py file2.py ... 

   # update and overwrite.
   # Original files are overwritten by updated script files.
   $ python -m qgate.tools.update_script -o file1.py file2.py ... 
		

if_ clause
-----------

if\_ clause will be changed not to accept function as cond, but accept a list of values of 0, 1 and None.  If a reference is not measured yet, its referred value is set to None.


.. code-block:: python
		
    qregs = new_qreg(3)
    
    # ... applying gates to qregs
    
    refs = new_references(2)
    m0 = measure(refs[0], qregs[0])
    m1 = measure(refs[1], qregs[1])
    circuit += [m0, m1] # adding measure operations
      
    # function is not accepted from 0.3
    # def pred(values) :
    #    return values[0] == 0 and values[1] == 1
    # circuit += [if_(refs, pred, [X(qregs[2]]]), ...]

    # From 0.3, please use the following.
    cond = [0, 1]
    # X gate is applied when cond matches values pointed by refs.
    circuit += [if_(refs, cond, [X(qregs[2]]]), ...]

Gate set consolidation
----------------------

Built-in gate set will be conslidated.

U1, U2 and U3 gates will be removed from built-in gates, and reimplemented as extensions.  These gates will be reimplemented as macro gates (or a gate group).

It does not mean unavailability of these gates from 0.3.  Script APIs of U1(), U2() and U3() will be provided in 0.3 and later. 

Sampling pool
-------------

Sampler class will be added, though details are not decided.