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Linux daemon using Python daemon with PID file and logging

The python-daemon package ( PyPI listing , Pagure repo ) is very useful. However, I feel it has suffered a bit from sparse documentation, an...

2011-06-08

Some Python introspection

Python has very powerful introspection capabilities. These let you examine any object (and everything is an object in Python) and extract information about it.

I am currently writing a script to monitor licenses for Matlab, and found occasion to use introspection. I have a string which is the name of a local variable in a function, and I want to extract the value of that local variable. (The variable is really an argument passed to the function.) Having the name of the variable as a string, how do I get its value?  Use the locals() function. locals() returns a dictionary of local variables.

    def check_licenses(checked_out=0, warning=10, critical=15): 
        # checked_out, warning, and critical are now local variables
        levels = ('warning', 'critical')
        for l in levels:
            if checked_out >= locals()[l]:
                print 'Licenses checked out are above threshold %s' % (l)

I found this mailing list post very useful.