PDI 1.4.0-alpha.2021-08-04.09fd084

the PDI data interface

Pycall plugin

The Pycall plugin allows calling python scripts from yaml file, that can work either if wanted data was shared or program calls specific event.

Configuration

Simple plugin build:

plugins:
pycall: // name of plugin
on_event: // run script on event
testing: // name of an event
with: // data alias
exec: // python code which will be executed when the event is called
on_data: // run script on data share
data_name: // python code which will be executed when data_name is shared

Plugin tree

The root of plugin configuration (named pycall), is a dictionary that contains the following keys:

on_event

This option allows to execute written python code when specific event is called.

data: {a: {type: array, subtype: int, size: 3}}
plugins:
pycall:
on_event:
testing:
with: { a_python: $a }
exec: \"print(' * [P] I received $a =',a_python); a_python[1]=7; print(' * [P] changed it to $a =',a_python);\"

In this example pycall will run script on testing event. In the next step in with section alias name for data is generated. a will be a_python for execusion of the python code. Finally exec contains python code that will be executed on testing event.

There is also an option to set a list of executions:

data: {a: {type: array, subtype: int, size: 3}}
plugins:
pycall:
on_event:
testing:
- exec: #some_python_script
with: { a: $a }
- exec: #some_other_python_script
with: { b: $a }

on_data

This option allows to execute written python code when specific data is shared.

data: {a: {type: array, subtype: int, size: 3}}
plugins:
pycall:
on_data:
a: print(' * [P] I received $a =',a); a[1]=7; print(' * [P] changed it to $a =',a);\"

The on_data is a dictionary that contains data name with the python script that will be executed on share.

Examples

Full example of pycall plugin. For siplicity yaml file was included with c code in one file instead of creating separate files.

Yaml file named your_file:

logging: trace
data: {a: {type: array, subtype: int, size: 3}}
plugins:
pycall:
on_event:
testing:
with: { a_python: $a }
exec: \"print(' * [P] I received $a =',a_python); a_python[1]=7; print(' * [P] changed it to $a =',a_python);\"

C++ code:

int a[3] = {1, 2, 3};
printf(" * [C] starting with $a = [%d %d %d]\n", a[0], a[1], a[2]);
PDI_event("testing");
printf(" * [C] now I see $a = [%d %d %d]\n", a[0], a[1], a[2]);

Output from the program:

* [C] starting with $a = [1 2 3]
[PDI][13:51:26] *** trace: Sharing `a' Ref with rights: R = true, W = true
[PDI][13:51:26] *** trace: Calling `a' share. Callbacks to call: 0
[PDI][13:51:26] *** trace: Calling `testing' event. Callbacks to call: 1
* [P] I received $a = [1 2 3]
* [P] changed it to $a = [1 7 3]
* [C] now I see $a = [1 7 3]