Coding a simple state machine in python

Tim Daneliuk tundra at tundraware.com
Tue Feb 25 04:27:30 CET 2014


On 02/24/2014 08:55 PM, William Ray Wing wrote:
>
> On Feb 24, 2014, at 8:30 PM, Ronaldo <abhishek1899 at gmail.com> wrote:
>
>> How do I write a state machine in python? I have identified the states and the conditions. Is it possible to do simple a if-then-else sort of an algorithm? Below is some pseudo code:
>>
>> if state == "ABC":
>>    do_something()
>>    change state to DEF
>>
>> if state == "DEF"
>>    perform_the_next_function()
>> ...
>>
>> I have a class to which certain values are passed from a GUI and the functions above have to make use of those variables. How do I go about doing this? I have the following algorithm:
>>
>> class TestClass():
>>     def __init__(self, var1, var2): #var1 and var2 are received from a GUI
>>        self.var1 = var1
>> ...
>>     if state == "ABC"
>>        doSomething(var1, var2)
>> ..
>>
>> Could someone point me in the right direction? Thank you!
>>
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>
> And, to extend Tim's suggestion of a dictionary just a bit, note that since Python functions are happy to pass function names as arguments, you can use a dictionary to make a really nice compact dispatch table.  That is, function A does its thing, gets to a new state, and returns as one of its return arguments the key into the dictionary that points to the next function_name to be called based on that new state.
>
> Stackoverflow has a couple of compact examples here:
>
> http://stackoverflow.com/questions/715457/how-do-you-implement-a-dispatch-table-in-your-language-of-choice
>
> Bill
>


Now you're making it TOO easy Bill ;)

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Tim Daneliuk     tundra at tundraware.com
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