Created
September 7, 2019 05:55
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Intercept and modify `pyqtSignal`s.
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| """Provides signalTap, a generic class to transform a pyqtSignal. | |
| Usage example: Intercept a spinbox's valueChanged signal. | |
| ```python | |
| def __init__(self): | |
| valueChangedTap = signalTap(lambda val: | |
| (val * self.unitValue[self.siUnit],) ) | |
| self.valueChanged.connect(valueChangedTap.emit) | |
| self.valueChanged = valueChangedTap | |
| ``` | |
| """ | |
| class signalTap(): | |
| """Generic class to transform a pyqtSignal.""" | |
| def __init__(self, transformer): | |
| """Create a new signal with a transformer function to be | |
| called on the real signal value before propagation.""" | |
| self.callbacks = [] | |
| self.transformer = transformer | |
| def connect(self, fn): | |
| """Invoke the function `fn` when the signal is emitted.""" | |
| self.callbacks.append(fn) | |
| def disconnect(self, fn): | |
| """Do not call `fn` when the signal is emitted any more.""" | |
| self.callbacks.remove(fn) | |
| def emit(self, *args): | |
| """Emit the transformed signal, based on the | |
| untransformed input values. (Invokes transformer.)""" | |
| for callback in self.callbacks: | |
| callback(*self.transformer(*args)) | |
| def emitVerbatim(self, *args): | |
| """Emit the transformed signal, based on the | |
| pre-transformed input values. (Ignores transformer.)""" | |
| for callback in self.callbacks: | |
| callback(*args) |
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