On Thu, 30 Oct 2008 14:21:01 -0700, John [H2O] wrote:
> I would like to write a function to write variables to a file and modify
> a few 'counters'.
Are you talking about a function to generate Python source code?
> This is to replace multiple instances of identical
> code in a module I am writing.
Surely the right way to do this is to factor out the identical code into
a function, and then call the function.
> This is my approach:
>
> def write_vars(D):
> """ pass D=locals() to this function... """
> for key in D.keys():
> exec("%s = %s" % (key,D[key]))
That would be better written as:
for key,item in D.iteritems():
exec "%s = %s" % (key, item)
exec is a statement, not a function, and doesn't require brackets.
> outfile.write(...)
> numcount += 1
> do this, do that...
>
> the issue is that at the end, I want to return outfile, numcount, etc...
> but I would prefer to not return them explicitly, that is, I would just
> like that the modified values are reflected in the script. How do I do
> this? Using global? But that seems a bit dangerous since I am using
> exec.
What you are actually trying to do is unclear to me. Perhaps you could
try explaining better with a more concrete example?
I wounder whether this might be what you are after?
# start of script (untested)
counter = 0 # define a counter in the module scope (global)
filename = 'foo.txt'
def make_vars():
global outfile, numcount # force names to be in module scope
outfile = open(filename, 'w')
numcount = 99
try:
numcount
except NameError:
print "numcount doesn't exist yet, making it"
make_vars()
print numcount
# end script
But of course the above can be written much more concisely as:
# start of script (untested)
counter = 0
filename = 'foo.txt'
outfile = open(filename, 'w')
numcount = 99
print numcount
# end script
so I'm not really sure you're trying to do what you seem to be doing.
--
Steven
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