Creating or assigning variables from a dictionary in Python

Question

I tried to ask a question normally once in here but nobody understands what I want to ask. So I\'ve found example in PHP.

// $_POST = array(\'address\' =>         


        

Answer 1

I recommend creating a class to hold the variables you're trying to create. Alex Martelli's famous bunch recipe would get you almost all of the convenience you are asking for, without resorting to modifying the local symbol table (which the docs specifically warn against doing).

Answer 2

Horribly late to the game, but I needed exactly this, and my solution was:

mydict = {'raw':'data', 'code': 500}
raw, code = [mydict.get(k) for k in ['raw','code']]

That way it's explicit for reading and there's no potential clobbering of locals() (which is a magic that I'd rather avoid).

Answer 3

OK php brothers so here is a bad news, python can't create variables from out of space... like php can: ${$var} . To use local() is a very bad idea, because you'll have tons of problems with debugging, and there some locals already defined in there.. so it's really bad thing to do...

You can't create this programmatically like php does. I think it's called non-explicity, and this is one python general: You ALWAYS know variable name. This kind of stuff just a suicide in some cases, you need to write by hand tons of vars... Mostly i was unhappy because of things like XML parsing, but it appears that there are method how to convert python dictionary into class, I was told about this yesterday but still haven't checked how it works ( something like here )

Answer 4

Nothing really new here, just a consolidation of one anwser and an illustration of what @John Y meant in his answer:

mydict = {'raw': 'data', 'code': 500}

def extract(dct, namespace=None):
    if not namespace: namespace = globals()
    namespace.update(dct)

extract(mydict)
print raw
print code

class Extract:
    def __init__(self, dct):
        self.__dict__.update(dct)

obj = Extract(mydict)
print obj.raw
print obj.code

Answer 5

I tried @Frédéric Hamidi's answer and found that locals() only works in the main script and does NOT work in any functions. So I did a bit of searching, and find out that locals() is READ ONLY. The reason it works in main script, is probably cause locals() is the same as globals() there, and globals() can be modified.

So I would suggest using globals().update() instead.

But it is going to pollute your global namespace. So this trick is even less clean than locals().

Answer 6

You can also use the exec keyword in a loop.

d = dict(param='hello', param2=500, param3=[1,2,3])
for k, v in d.iteritems():
    exec '%s = v' % k

But this certainly feels unpythonic. exec feels a bit esoteric and you should probably just restructure your code so you don't have to do this.