In order to use pyRobotics (or any other package) you need to have a copy of the package in any of the folders included in the python path. You can do this in two ways: installing from a source distribution file from the dist folder in the source repository or from pypi, or manually copying the source package into a location in the PYTHONPATH. You can download the package from here.
Note
Note that the git repository includes some examples, as well as the library, the package is the FOLDER named pyRobotics within the repository.
To install from a distribution file
Simply extract the contents of the file with the command tar -xzvf pyRobotics-<version>.tar.gz and then run python setup.py install (You might need superuser permissions).
To copy the source package in a location in the PYTHON_PATH
To know which folders are in the PYTHON_PATH, open an interactive console and type:
>>> import sys
>>> sys.path
Alternatively, you can modify your python configuration to include in the PYTHON_PATH whichever folder pyRobotics is located in.
A command handler is a function that receives a Command object and returns a Response object.
The Response object should be created by the class function Response.FromCommandObject(). This is important because every command has an internal id to keep track of commands and responses, and this functions creates the approppriate response.
Here you can see an example of a command handler:
def myCommandHandler(commandObj):
params = parseCommandParams(commandObj.params)
if executeCommand(params):
return Response.FromCommandObject(commandObj, True, "answer successful")
return Response.FromCommandObject(commandObj, False, "answer UNsuccessful")
Notice that the last parameter is meant to be the actual return value of the command, in case the command should answer something, such as a list of recognized objects, the name of a recognized face, etc. If the command is not supposed to answer anything but whether it was successful or not, it doesn’t matter what this parameter has, it can be an empty string or they keyword None, in which case the response will be sent with the original parameters.
A subscription hanlder is a function that will execute whenever a notification of an updated shared variable is received. (Whenever somebody writes to it). It receives a SharedVar object and should not return anything.
Since the function receives the SharedVar object, it has the information of what type of shared var it is, and its data, so there could be one subscription handler for more than one shared variable (or all) and the handler should then decide what to do with them.
Here’s an example of a simple subscription handler that prints the info of the shared variable:
def mySubscriptionHandler(sv):
print '----------------------------'
print 'Shared Variable updated:'
print sv.varName
print sv.svType
if sv.size >= 0:
print sv.size
print sv.data
This is an example included with the source code:
import time
from pyrobotics import BB
from pyrobotics.parallel_senders import ParallelSender
from pyrobotics.messages import Command, Response
# These command handler functions could (and probably should) be defined in another module
# as to keep the main program file simple and clean.
def testFunction(c):
print "testFunction called..."
print 'Params: ' + c.params
return Response.FromCommandObject(c, True, 'Command response')
fmap = {
'tst_testfunction' : testFunction
}
def main():
BB.Initialize(2000, fmap)
BB.Start()
BB.SetReady(True)
print 'Sending command say...'
print BB.SendAndWait(Command('spg_say', 'This is a test.'), 5000, 3)
print 'Sending Async command...'
ps = ParallelSender(Command('othertst_slowfunction', 'This is another test.'), 5000, 3)
while ps.sending:
print 'sending...'
time.sleep(0.3)
print 'Response received...'
print ps.response
BB.Wait()
if __name__ == "__main__":
main()