Seldon wrote:
On 03/25/2011 12:05 AM, Steven D'Aprano wrote:
On Thu, 24 Mar 2011 19:39:21 +0100, Seldon wrote:
Hi, I have a question about generating variable assignments
dynamically.
[...]
Now, I would like to use data contained in this list to dynamically
generate assignments of the form "var1 = value1", ecc where var1 is an
identifier equal (as a string) to the 'var1' in the list.
Why on earth would you want to do that?
Because I'm in this situation. My current code is of the form:
var1 = func(arg=value1, *args)
..
varn = func(arg=valuen, *args)
where var1,..varn are variable names I know in advance and
value1,..valuen are objects known in advance, too; func is a long
invocation to a factory function. Each invocation differs only for
the value of the 'arg' argument, so I have a lot of boilerplate code
I'd prefer to get rid of (for readability reasons).
I thought to refactor the code in a more declarative way, like
assignment_list = (
('var1', value1),
('var2', value2),
.. ,
)
for (variable, value) in assignment_list:
locals()[variable] = func(arg=value, *args)
My question is: what's possibly wrong with respect to this approach ?
First thing, locals help states the following:
"Note The contents of this dictionary should not be modified; changes
may not affect the values of local and free variables used by the
interpreter"
http://docs.python.org/library/functions.html#locals
Can't you use something like
rootValues = { 'var1': 45, 'var2': 0, }
def func2x(x):
return x*2
def main():
mappedValues = {}
for varName in rootValues:
mappedValues[varName] = func2x(rootValues[varName])
print mappedValues[varName]
main()
> 90
> 0
JM
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