pyDevSup/python/devsup/_nullapi.py

def verinfo():
    """(VER, REV, MOD, PATH, "site") = verinfo()
    
    Query EPICS version information
    """
    return (0,0,0,0,'invalid')

class _Record(object):
    """Handle for record operations
    
    r = _Record("rec:name")
    """

    def __init__(self, rec):
        pass
    def name(self):
        """Record name string.
        
        >>> R = getRecord("my:record:name")
        >>> R.name()
        "my:record:name"
        """
    def rtype(self):
        """Record type name string.
        
        >>> R = getRecord("my:record:name")
        >>> R.type()
        "longin"
        """
    def isPyRecord(self):
        """Is this record using Python device support.
        
        :rtype: bool
        """
    def info(self, key):
        """info(key)
        info(key, default)
        
        Lookup record info tag.  If no default
        is provided then an exception is raised
        if the info key does not exist.
        """
    def infos(self):
        """Return a dictionary of all info tags
        for this record
        """

    def scan(self, sync=False, reason=None, force=0):
        """Scan this record.
        
        :param sync: scan in current thread (``True``), or queue (``False``).
        :param reason: Reason object passed to :meth:`process <DeviceSupport.process>` (sync=True only)
        :param force: Record processing condtion (0=Passive, 1=Force, 2=I/O Intr)
        :throws: ``RuntimeError`` when ``sync=True``, but ``force`` prevents scanning.
        
        If ``sync`` is False then a
        scan request is queued to run in another thread..
        If ``sync`` is True then the record
        is scannined immidately on the current thread.
        
        For ``reason`` argument must be used in conjunction with ``sync=True``
        on records with Python device support.  This provides a means
        of providing extra contextual information to the record's
        :meth:`process <DeviceSupport.process>` method.
        
        ``force`` is used to decide if the record will actuall be processed,
        ``force=0`` will only process records with SCAN=Passive.
        ``force=1`` will process any record if at all possible.
        ``force=2`` will only process records with Python device support and
        SCAN=I/O Intr.
        
        It is **never** safe to use ``sync=True`` while holding record locks,
        including from within a *process* method.
        """

    def asyncStart(self):
        """Start asynchronous processing
        
        This method may be called from a device support
        :meth:`process <DeviceSupport.process>` method
        to indicate that processing will continue
        later.
        
        ..  important::
          This method is **only** safe to call within a *process* method.
        """
    def asyncFinish(self, reason=None):
        """Indicate that asynchronous processing can complete
        
        Similar to :meth:`scan`.  Used to conclude asynchronous
        process started with :meth:`asyncStart`.
        
        Processing is completed on the current thread.
        
        ..  important::
          This method should **never** be called within
          a :meth:`process <DeviceSupport.process>` method,
          or any other context where a Record lock is held.
          Doing so will result in a deadlock.

        Typically a *reason* will be passed to *process* as a way
        of indicating that this is the completion of an async action. ::
        
          AsyncDone = object()
          class MySup(object):
            def process(record, reason):
              if reason is AsyncDone:
                record.VAL = ... # store result
              else:
                threading.Timer(1.0, record.asyncFinish, kwargs={'reason':AsyncDone})
                record.asyncStart()
        """

class _Field(object):
    """Handle for field operations
    
    f = Field("rec:name.HOPR")
    
    Field objects implement the buffer protocol.
    """
    def __init__(self, fld):
        pass
    def name(self):
        """Fetch the record and field names.
        
        >>> FLD = getRecord("rec").field("FLD")
        >>> FLD.name()
        ("rec", "FLD")
        """
    def fieldinfo(self):
        """(type, size, #elements) = fieldinfo()
        
        Type is DBF type code
        size is number of bytes to start a single element
        #elements is the maximum number of elements the field can hold
        """

    def getval(self):
        """Fetch the current field value as a scalar.
        
        :rtype: int, float, or str
        
        Returned type depends of field DBF type.
        An ``int`` is returned for CHAR, SHORT, LONG, and ENUM.
        A ``float`` is returned for FLOAT and DOUBLE.
        A ``str`` is returned for STRING.
        """

    def putval(self, val):
        """Update the field value
        
        Must be an Int, Float or str.  Strings will be truncated to 39 charactors.
        """

    def getarray(self):
        """Return a numpy ndarray refering to this field for in-place operations.
        
        The dtype of the ndarray will correspond to the field's DBF type.
        Its size will be the **maximum** number of elements.
        
        .. important::
          It is only safe to read or write to this ndarray while the record
          lock is held (ie withing :meth:`process <DeviceSupport.process>`).
        """

_hooks = {}