Anonymus functions revisited

[Ron]

On Tue, 22 Mar 2005 18:15:25 -0500, "George Sakkis"
<gsakkis at rutgers.edu> wrote:

>"Ron" <radam2 at tampabay.rr.com> wrote:
>> On Tue, 22 Mar 2005 21:56:57 GMT, Ron <radam2 at tampabay.rr.com> wrote:
>>
>> >Why should a function not create a local varable of an argument if the
>> >varable doesn't exist and a default value is given?
>>

>
>Yeap.. a simple one-liner can do the trick:
>
>def makeVars(**nameVals):
>    sys._getframe(1).f_locals.update(nameVals)
>
>try: b
>except NameError: print "Before makeVars: NameError"
>else: print "Before makeVars: Not NameError"
>makeVars(b=2)
>try: b
>except NameError: print "After makeVars: NameError"
>else: print "After makeVars: Not NameError"
>
>George
>

Cool! Thanks George,  so I can do this:

# Set a varable to a default value if it doesn't exist.
# Return the same value back if it does.
# Use: varable = dfvalue( varable=object)
def defvalue(**var):
    if var.keys()[0] not in sys._getframe(1).f_locals.keys():
        return var.values()[0]
    return  sys._getframe(1).f_locals[var.keys()[0]]

f = defvalue(f=0)  
print f           # 0

g = 19
g = defvalue(g=0)
print g           # 19


Would there be any problems with using this function?  

Not sure where I need it.  Was thinking it could be used inside
expressions somehow, and it was an iteresting problem. ;)

Ron