6.4. boing.nodes — The nodes of the pipeline

The module boing.nodes contains a set of generic utility nodes.

6.4.1. Device input/output

class boing.nodes.DataReader(inputdevice, postend=True, parent=None)

Producer node that anytime the device inputdevice send the signal readyRead it reads the device and it produces a message containing the data. The provided products is a dictionary {"str": data} if data is a string, otherwise the product will be a dictionary like {"data": data}. If the argument postend is set to True, the DataReader will never produce an empty product, like {"str": ""} or {"data": b""}. parent defines the parent of the node.

inputDevice()

Return the considered input device.

class boing.nodes.DataWriter(outputdevice, writeend=True, hz=None, parent=None)

Consumer node that anytime it receives some data, it writes the data to the device outputdevice. The DataWriter requires the products str if the output device is text enabled (see method isTextModeEnabled) otherwise it requires the product data. If the argument writeend is set to True, the DataWriter will never write an empty string; this can be useful in order to prevent a socket to close. parent defines the parent of the node.

outputDevice()

Return the considered output device.

6.4.2. Products debugging

class boing.nodes.Dump(request=Request.ANY, mode='items', separator='\n\n', src=False, dest=False, depth=None, parent=None)

Instances of the Dump class produce a string representation of the products they receive. The string is obtained using the function boing.utils.deepDump().

The parameter request must be an instance of the class boing.core.Request and it is used to select the product to be dumped. The default value for request is Request.ALL. mode defines how the received products will be dumped. The available values are:

• 'keys', only the matched keys are written;
• 'values', only the values of the matched keys are written;
• 'items', both the keys and values are written.

separator defines the string to be written between two products. The default value for separator is '\n\n'. src defines whether the node also dumps the producer of the received products. The default for src is False. The paramenter dest defines whether the node adds a reference to itself when it dumps the received products; its default value is False. The parameter depth defines how many levels of the data hierarchy are explored and it is directly passed to the boing.utils.deepDump() function.

mode()

Return the node’s mode.

setMode(mode)

Set the node’s dump mode.

6.4.3. Products editing

class boing.nodes.Editor(dict, blender, parent=None)

Instances of the Editor class apply to the received products the (key, values) pairs of dict.

blender defines the output of the node (see boing.core.Functor). parent must be a PyQt4.QtCore.QObject and it defines the node’s parent.

get(key, default=None)

Return the value for key if key is in the editor’s dictionary, else default. If default is not given, it defaults to None.

set(key, value)

Set the value for key to value.

items()

Return a new view of the editor dictionary’s items ((key, value) pairs).

class boing.nodes.DiffArgumentFunctor(functorfactory, request, blender=Functor.MERGECOPY, parent=None)

It takes a functorfactory and for each different argument path, it creates a new functor which is applied to the argument value. The args must be a diff-based path so that functor can be removed depending on ‘diff.removed’ instances.

6.4.4. Timing utilities

class boing.nodes.Timekeeper(blender=Functor.MERGECOPY, parent=None)

Instances of the Timekeeper class tag each received product with the timestamp when the product is received; then they forward the product.

blender defines the output of the node (see boing.core.Functor). parent must be a PyQt4.QtCore.QObject and it defines the node’s parent.

class boing.nodes.Lag(msec, parent=None)

Instances of the Lag class forward the received products after a delay.

The parameter msec defines the lag in milliseconds. parent must be a PyQt4.QtCore.QObject and it defines the node’s parent.