Python generating Python

Question

I have a group of objects which I am creating a class for that I want to store each object as its own text file. I would really like to store it as a Python class definition which subclasses the main class I am creating. So, I did some poking around and found a Python Code Generator on effbot.org. I did some experimenting with it and here's what I came up with:

# # a Python code generator backend # # fredrik lundh, march 1998 # # [email protected] # http://www.pythonware.com # # Code taken from http://effbot.org/zone/python-code-generator.htm  import sys, string  class CodeGeneratorBackend:      def begin(self, tab="\t"):         self.code = []         self.tab = tab         self.level = 0      def end(self):         return string.join(self.code, "")      def write(self, string):         self.code.append(self.tab * self.level + string)      def indent(self):         self.level = self.level + 1      def dedent(self):         if self.level == 0:             raise SyntaxError, "internal error in code generator"         self.level = self.level - 1  class Point():     """Defines a Point. Has x and y."""     def __init__(self, x, y):         self.x = x         self.y = y      def dump_self(self, filename):         self.c = CodeGeneratorBackend()         self.c.begin(tab="    ")         self.c.write("class {0}{1}Point()\n".format(self.x,self.y))         self.c.indent()         self.c.write('"""Defines a Point. Has x and y"""\n')         self.c.write('def __init__(self, x={0}, y={1}):\n'.format(self.x, self.y))         self.c.indent()         self.c.write('self.x = {0}\n'.format(self.x))         self.c.write('self.y = {0}\n'.format(self.y))         self.c.dedent()         self.c.dedent()         f = open(filename,'w')         f.write(self.c.end())         f.close()  if __name__ == "__main__":     p = Point(3,4)     p.dump_self('demo.py') 

That feels really ugly, is there a cleaner/better/more pythonic way to do this? Please note, this is not the class I actually intend to do this with, this is a small class I can easily mock up in not too many lines. Also, the subclasses don't need to have the generating function in them, if I need that again, I can just call the code generator from the superclass.

Answer 1

We use Jinja2 to fill in a template. It's much simpler.

The template looks a lot like Python code with a few {{something}} replacements in it.