How to generate variables in a particular class?

Question

I am building a physics engine in python, and am trying to make a function, preferably a generator, which makes a defined number of variables with systematically assigned names in the self-defined class "particle."
But to do so, I need to alter the variable name with each iteration, for which I need to alter the code in the function itself, which is hard to find tutorials of.
My target is something along the lines of

def gen_parts(part_amount, basename, mass, charge):
  counter_2 = 0
  while counter_2 < part_amount:
    #generate position and velocity: v = [v_x, v_y] and s = [s_x, s_y]
    name = basename+"_"+str(counter)
    code(name) = GenPart(counter, s, v, mass, charge) #I need the code() function from here, somehow
    counter += 1

How can I do this?

possible duplication of https://stackoverflow.com/questions/1167398/python-access-class-property-from-string — jhandei, Nov 04 '19 at 17:02
Possible duplicate of [Python: access class property from string](https://stackoverflow.com/questions/1167398/python-access-class-property-from-string) — jhandei, Nov 04 '19 at 17:02
Possible duplicate of [How to access object attribute given string corresponding to name of that attribute](https://stackoverflow.com/questions/2612610/how-to-access-object-attribute-given-string-corresponding-to-name-of-that-attrib) — wwii, Nov 04 '19 at 17:31

score 2 · Answer 1 · answered Nov 04 '19 at 17:04

You don't want to dynamically generate differently-named attributes (it's possible, but you don't want to do it). Instead you want your class attribute to be some sort of data structure (like a List or a Dict) and just add your attributes to it. If you just want to keep an ordered list of them (like you want to make 10 vectors or whatever), a List is good; if you want to associate them with some other data (like names) then that's what a Dict is for.

It might look something like:

def gen_parts(self, part_amount, mass, charge):
    self.parts = []  # initialize self.parts to be an empty list
    while len(self.parts) < part_amount:
        #generate position and velocity: v = [v_x, v_y] and s = [s_x, s_y]
        self.parts.append(GenPart(s, v, mass, charge))

I took out the counter and basename on the theory that they're needless complications; the list (self.parts) automatically keeps track of how many elements it contains and makes each element uniquely accessible by its index (the order in which it was added).

How to generate variables in a particular class?

1 Answers1