[Tutor] python connect() function

[Peter Otten]

Pierre Barthelemy wrote:

> I have a question about event handling and the use of the connect
> function. I have a data object, that contains a series of signals, one
> being "new_data_point" .
> 
> When i want to plot the data, i also connect the "new_data_point" event to
> the function "analysis_client.update_plot". I therefore run the line:
> 
> data.connect('new_data_point', analysis_client.update_plot)
> 
> In this case, everytime the data object is updated, i also update the
> plot.
> 
> 
> I would like to adapt this code to allow to have several plots, connected
> to several data objects. I would therefore need to specify, when i connect
> the "update_plot" function, which plots needs to be updated.
> Is it possible to specify arguments to be used by the connected function
> when the event occurs ? For instance, is there a way to write something
> like:
> 
> data.connect('new_data_point',
> analysis_client.update_plot(specific_plot_instance))
> 
> So that when the event occurs, the corresponding plot (and only this one)
> is updated ?

Like Walter I have no idea what framework or library you are talking about. 
The generic answer is yes: Basically you have to make a new function that 
calls the method with a specifc plot instance.

def update_specific_plot():
    analysis_client.update_plot(specific_plot_instance)
data.connect("new_data_point", update_specific_plot)

A more elegant and more general version of the above would create the helper 
function on the fly using functools.partial():

from functools import partial

data.connect("new_data_point",
    partial(analysis_client.update_plot, specific_plot_instance))