OOP编程风格决定

Question

I just have a quick question about an OOP programming I've been having difficulty deciding. The premise is that I'm making a set of very simple geometric classes such as vertex and angle and vector objects, but one of the classes, the line class to be specific, is a little different. It's basically just a collection of methods that I use one time only, I never actually save a line object for later use or recollection of data anywhere else in the program. An example usage to demonstrate my point would be this:

class Line:
    def __init__(self, vertex1, vertex2):
        self.start = vertex1
        self.end = vertex2
    def to_the_left(self, vertex):
        """Check to see if a vertex is to the left of the line segment."""
        #code stuff

data = Line(Vertex(0, 0), Vertex(10, 0)).to_the_left(Vertex(5, 5))

I only ever instantiate Line(Vertex(0, 0), Vertex(10, 0)) once to retrieve the data . So I was thinking that I might as well just have a bunch of functions available instead of packing it all into a class, but then I was skeptical about doing that since there are a ton of methods that would have to be converted to functions.

Another thing I was thinking of doing was to make a Line class and then convert all it's methods into normal functions like so:

#continuing from the code above
def to_the_left(line_start, line_end, vertex):
    return Line(line_start, line_end).to_the_left(vertex)
data = to_the_left(Vertex(0, 0), Vertex(10, 0), Vertex(5, 5))

Which method do you think I should use?

Answer 1

I would opt for using an object as you might need to do multiple operations on Line.

For example you might compute the length, if it's to the left, and some other operation. You might need to pass the Line around who knows.

One thing you might want to consider is instead of using Line and Vertex, use Vector which acts as both. If your vertex has x,y you can make a Vector that has x,y,w. In this scheme w=1 for vertices and w=0 for Lines - it would simplify a lot of code.

Look up Homogenous coordinates to learn more