Python 如何从包含参数的字符串中调用 class 方法

Question

I have the following code. What would be the best way to evaluate the command variable and the parameters it contains.

This is a contrived example, but the easiest way to explain what I am trying to do on a bigger scale.

class Job():
  def random_number(self, start, end, prec=0):
    number = round(random.uniform(start,end),prec)
    if(prec == 0):
      return int(number)
    return number

  def run(self, command):
    #command = "self.random_number(1,10,0)"
    #**************
    # What would be the best way to 'eval' the content of the 'command' variable and the parameters it contains?
    #**************

job = Job()
job.run("self.random_number(1,10,0)")

Answer 1

Generally, this seems a bad idea, consider restructuring your code. That said, you may make use of getattr(...) in combination with splitting your string into a function and a params part:

import random, re

class Job():
    def random_number(self, start, end, prec=0):
        number = round(random.uniform(start, end), prec)
        if (prec == 0):
            return int(number)
        return number

    def run(self, command):
        fun, params, _ = re.split(r'[()]', command)
        params = map(int, params.split(","))

        func = getattr(Job, fun)
        print(func(*params))

job = Job()
job.run("random_number(1,10,0)")

Obviously, you'd need to add some error management (broken strings, functions, that don't exist, floats instead of integers - you get the idea).

Answer 2

You can use the eval() function like so:

 def run(self, command):
    return eval(command)

would this work for you?