Python将类和主程序分离到不同的文件中

Question

我正在学习 Python 中的面向对象编程技术。创建了一个变得越来越长、越来越复杂的向量类后，我想通过创建一个单独的文件将我的类与主程序分开。随后可以在需要时将该类导入到主程序中。

这是包含类向量的文件vector_class.py

class vector(object):

    def __init__(self, x=None, y=None, z=None, angle=None):

        if angle == None:
            self.x, self.y, self.z = x, y, z
        if angle != None:
            if angle == "rad":
                self.r, self.theta, self.phi = x, y, z
            if angle == "deg":
                self.r = x
                self.theta = y * 2. * pi / 360.
                self.phi = z * 2. * pi / 360.
            self.x = self.r * sin(self.theta) * cos(self.phi)
            self.y = self.r * sin(self.theta) * sin(self.phi)
            self.z = self.r * cos(self.theta)

    def show(self):
        print "[", self.x, "\t", self.y, "\t", self.z, "]"

    def write(self):
        file.write("[" + str(self.x) + ",\t" + str(self.y) + ",\t" + str(self.z) + "]")
    def write_sph(self):
        file.write("[" + str(self.mag()) + ",\t" + str(self.gettheta()) + ",\t" + str(self.getphi()) + "]")
    def swrite(self):
        file.write(str(self.x) + "\t" + str(self.y) + "\t" + str(self.z))
    def swrite_sph(self):
        file.write(str(self.mag()) + "\t" + str(self.gettheta()) + "\t" + str(self.getphi()))

    def getx(self):
        return self.x
    def gety(self):
        return self.y
    def getz(self):
        return self.z

    def setx(self, x):
        self.x = x
    def sety(self, y):
        self.y = y
    def setz(self, z):
        self.z = z

    def square(self):
        return self.x*self.x + self.y*self.y + self.z*self.z
    def mag(self):
        return sqrt(self.square())

    def gettheta(self):
        return arccos(self.z / self.mag())
    def getphi(self):
        return arctan2(self.y, self.x) # sign depends on which quadrant the coordinates are in

    def add(self, v):
        v_sum = vector(self.getx() + v.getx(), self.gety() + v.gety(), self.getz() + v.getz())
        return v_sum
    def minus(self, v):
        v_minus = vector(self.getx() - v.getx(), self.gety() - v.gety(), self.getz() - v.getz())
        return v_minus
    def diff(self, v):
        v_diff = vector(abs(self.getx() - v.getx()), abs(self.gety() - v.gety()), abs(self.getz() - v.getz()))
        return v_diff
    def inc(self, const): 
        v_new = vector(self.getx() + const, self.gety() + const, self.getz() + const)
        return v_new
    def times(self, const):
        v_new = vector(self.getx() * const, self.gety() * const, self.getz() * const)
        return v_new
    def div(self, const):
        v_new = vector(self.getx() / const, self.gety() / const, self.getz() / const)
        return v_new
    def sprod(self, v):
        ans = self.getx() * v.getx() + self.gety() * v.gety() + self.getz() * v.getz()
        return ans
    def vprod(self, v):
        v_new = vector()
        v_new.setx(self.gety() * v.getz() - self.getz() * v.gety())
        v_new.sety(self.getz() * v.getx() - self.getx() * v.getz())
        v_new.setz(self.getx() * v.gety() - self.gety() * v.getx())
        return v_new

这是包含导入类向量的主程序的文件section2.py

from numpy import *
from vector_class import vector

v0 = vector(0., 0., 0.)
v1 = vector(-1.3054, 7.4033, 2.7362)
v2 = vector(8., 70., 100., "deg")
v3 = vector(8., 1.2217, 1.7453, "rad")

file = open("tasks.txt", 'w')

file.write("task 1 : method to print to file \n\n")
file.write("v0 = ")
v0.write()
file.write("\nv1 = ")
v1.write()

file.write("\n\ntask 2 : spherical polar constructor \n\n")
file.write("v2 = ")
v2.write()
file.write("\nv3 = ")
v3.write()

file.write("\n\ntask 3 : accessing individual coordinates \n\n")
file.write("v1 x component = " + str(v1.getx()) + "\n")
file.write("v1 y component = " + str(v1.gety()) + "\n")
file.write("v1 z component = " + str(v1.getz()) + "\n")

file.write("\ntask 4 : square and magnitude of the three vector \n\n")
file.write("v1 squared = " + str(v1.square()) + "\n")
file.write("v1 magnitude = " + str(v1.mag()) + "\n")

file.write("\ntask 5 : calculating spherical polar angles \n\n")
file.write("v1 spherical = ")
v1.write_sph()
file.write("\nv2 spherical = ")
v2.write_sph()
file.write("\nv3 spherical = ")
v3.write_sph()

file.write("\n\ntask 6 : modifying individual coordinates \n\n")
file.write("v0 = ")
v0.write()
v0.setx(7.77), v0.sety(8.88), v0.setz(9.99)
file.write("\nv0 = ")
v0.write()

file.write("\n\ntask 7 : adding vectors the hard way\n\n")
v4 = vector()
file.write("v0 + v1 = ")
v4.setx(v0.getx() + v1.getx())
v4.sety(v0.gety() + v1.gety())
v4.setz(v0.getz() + v1.getz())
v4.write()

file.write("\n\ntask 8 : overloading the add operator\n\n")
v4 = v0.add(v1)
file.write("v0 + v1 = ")
v4.write()

file.write("\n\ntask 9 : overloading the minus and increment operators \n\n")
v5 = v0.minus(v1)
file.write("v0 - v1 = ")
v5.write()
v6 = v0.inc(3.)
file.write("\nv0 += 3. = ")
v6.write()

file.write("\n\ntask 10 : scaling a vector \n\n")
v7 = v0.times(2.)
file.write("v0 * 2 = ")
v7.write()
v8 = v0.div(2.)
file.write("\nv0 / 2 = ")
v8.write()

file.write("\n\ntask 11 : the scalar product \n\n")
file.write("v0 . v1 = " + str(v0.sprod(v1)))

file.write("\n\ntask 12 : the vector product \n\n")
v9 = v0.vprod(v1)
file.write("v0 x v1 = ")
v9.write()

file.write("\n\ntask13 : triple product test \n\n")
file.write("v0 . (v0 x v1) = " + str(v0.sprod(v0.vprod(v1))))

file.close()
exit()

当我运行主程序时，我收到错误TypeError:描述符'write'需要一个'file'对象但收到了'str'，但如果所有代码都在一个文件中，则所有内容工作正常。为什么我会收到错误以及如何让类和主程序的两个单独文件一起工作？

Answer 1

文件是 built-in name ，因此命名变量 file 可能会破坏一些东西。 file 未在 vector.py 中定义，因此您调用 write()文件对象的函数，但您将其作为静态函数调用，因此它不起作用。我同意 @roippi 关于添加文件对象作为 vector 构造函数的参数的观点:

def __init__(self, f, x=None, y=None, z=None, angle=None)

我在这里将其重命名为 f 以避免我提到的第一个问题，但您可以将其称为其他名称。您现在只需要进行查找和替换，将 vector.py 中的“file”替换为“f”即可。