Python生成Python [英] Python generating Python

问题描述

我有一组对象，我正在为其创建一个类，希望将每个对象存储为自己的文本文件。我真的很想将其存储为Python类定义，该类继承了我正在创建的主类。因此，我进行了一些探索，并在effbot.org上找到了Python代码生成器。我做了一些实验，这是我想出的：

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
#
# [e-mail]
# 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')

那感觉真的很丑，有没有一种更清洁/更好/更多pythonic的方式来做到这一点？请注意，这不是我实际上打算使用的类，这是一个小类，我可以轻松地在不多的行中进行模拟。另外，子类不需要在其中具有生成函数，如果再次需要，我可以从超类调用代码生成器。

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.

推荐答案

我们使用Jinja2填写模板。

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

模板看起来很像Python代码，其中一些替换为 {{something}}

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

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