Package twisted :: Package flow :: Module stage :: Class Filter
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Class Filter

Instruction --+    
              |    
          Stage --+
                  |
                 Filter


flow equivalent to filter:  Filter(function, stage, ... )

Yield those elements from a stage for which a function
returns true.   If the function is None, the identity 
function is assumed, that is, all items yielded that are
false (zero or empty) are discarded.

    def odd(val):
        if val % 2:
            return True
    
    def range():
        yield 1
        yield 2
        yield 3
        yield 4
    
    source = flow.Filter(odd,range)
    printFlow(source)

Method Summary
  __init__(self, func, stage, *trap)
  __iter__(self)
(inherited from Stage)
  next(self)
return current result (inherited from Stage)
  _yield(self)
executed during a yield statement by previous stage

Method Details

_yield(self)

executed during a yield statement by previous stage

This method is private within the scope of the flow module, it is used by one stage in the flow to ask a subsequent stage to produce its value. The result of the yield is then stored in self.result and is an instance of Failure if a problem occurred.
Overrides:
twisted.flow.base.Stage._yield (inherited documentation)

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