[Python-Dev] A Testing language Construct that could also be a Distributed programming construct - How can this be done in Python

[Saravanan Shanmugham (sarvi)]

I am using Python as a test language and wondering how best to represent
what is shown below in TTCN-3 
TTCN-3, a testing domain specific language has a construct that looks
like below  Its trying to send a request and define 3 alternative
outcomes/events.
 
web_port.send("http://www.googe.com/")
resonseTimer.start(300)
alt {
    [] web_port.receive("something") {
        responseTimer.stop;
        setverdict(pass);
    }
    [] web_port.receive("somethingelse") {
        responseTimer.stop;
        setverdict(fail);
    }
    [] responseTimer.timeout {
        setverdict(fail);
    }
}
 
I am trying to do something similar with python and find myself in a fix
as to how to code it clean. 
 
I can't do it with
 if ...elseif ... elseif .... else 
unless I wrap it in an event loop.
Since otherwise it means that each condition function will be executed
once.  While what we are looking for is way to define potential events
that can happen and a particular segment of code to executed for a
specific event match
 
The closest thing that I can do is something like this, assuming I
implement the doalternatives method to take a list of function, code
pairs.  It would take the list of function-name, parameters list and run
it in an event loop or in separate threads as the need may be to match
one of them. 
When one of them matches it would be expected to run the code block
associated with it. Which would get me the same behaviour.
 
doalternatives(
    [web_port.receive,"something"],
            "responseTimer.stop; 
             setverdict(pass);"
    [web_port.receive,"somethingelse"],
            "responseTimer.stop; 
             setverdict(fail);"
    [responseTimer.timeout],
            "responseTimer.stop; 
             setverdict(pass);"
}
 
The above looks pretty ok. Except that I have to define the python code
block as a string.
It would be nice if there was a python language construct that would
allow me to define a block of python code that can be passed as a code
object into a function.
 
That would serve the above purpose as well as cases for distributed or
parallel programming as well.
 
A construct like
invoke doalternatives with:
    param [web_port.receive,"something"]
    param:
        responseTimer.stop()
        setverdict(pass)
    param [web_port.receive,"something else"]
    param:
        responseTimer.stop()
        setverdict(fail)
    param [responseTimer.timeout]
    param:
        responseTimer.stop()
        setverdict(pass)
 
I am sure we can do better than what I have proposed above. But the
general idea is to be able to define and pass code segments as code
objects around a function invocation and and pass the code objects as
parameters into the invoked function.
 
What do people think? Is there any existing construct that I might be
missing to achieve the above?
 
Sarvi
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