CODEWITHSUNDEEP
python
TJR
TJR

Reputation: 484

Merge get and set functions python

I am implementing a class with a huge amount of variables. In that class, I want to do a get function and a set function, these functions will have 4 (2 in the example) arguments. For example:

class MyClass(object):
    def __init__(self):
        self.var1 = 0
        self.var2 = 0
        self.var3 = 0
        self.var4 = 0

    def get(self, arg1, arg2):
        if arg1 and arg2:
            return self.var1
        elif not arg1 and arg2:
            return self.var2
        elif arg1 and not arg2:
            return self.var3
        else:
            return self.var4

    def set(self, arg1, arg2, value):
        if arg1 and arg2:
            self.var1 = value
        elif not arg1 and arg2:
            self.var2 = value
        elif arg1 and not arg2:
            self.var3 = value
        else:
            self.var4 = value

As you can see, my problem is that switch-case \ if-elif-else part, that I couldn't find a way to export to one function. What is the beautiful python way to do it?

Upvotes: 1

Views: 96

Answers (4)

user2390182
user2390182

Reputation: 73470

E.g. use an array variable and calculate an index from your arguments:

class MyClass(object):
    def __init__(self):
        self.var = 4 * [0]

    def index(self, arg1, arg2):
        return 2*int(bool(arg1)) + int(bool(arg2))  # possible results: 0, 1, 2, 3

    def get(self, arg1, arg2):
        return self.var[self.index(arg1, arg2)]

    def set(self, arg1, arg2, value):
        self.var[self.index(arg1, arg2)] = value

Upvotes: 1

zephyr
zephyr

Reputation: 2332

Why not something like the following:

class MyClass(object):
    def __init__(self):
        self.var1 = 0
        self.var2 = 0
        self.var3 = 0
        self.var4 = 0

    def view(self, arg1, arg2, value = None):
        if arg1 and arg2:
            if value is not None: self.var1 = value
            return self.var1
        elif not arg1 and arg2:
            if value is not None: self.var2 = value
            return self.var2
        elif arg1 and not arg2:
            if value is not None: self.var3 = value
            return self.var3
        else:
            if value is not None: self.var4 = value
            return self.var4

Then you just have something like:

myclass = MyClass()
myclass.view(0,1,1)   # Changes the value, returns to nothing
x = myclass.view(0,1) # Doesn't change value, returns to "x"

Not sure if you're constrained by other conditions, but you can certainly simplify this process by making all your var parameters a value in a list or array and indexing it based on arg1 and arg2 values. You can create an index numpy array like:

self.index = numpy.array([[0,1],[2,3]])

then you variable array would be

self.var = np.array([0,0,0,0])

Now your method doesn't need all those if/elifs

def view(self, arg1, arg2, value = None)
    if value is not None: self.var[self.index[arg1,arg2]] = value
    return self.var[self.index[arg1,arg2]]

Upvotes: 0

L3viathan
L3viathan

Reputation: 27293

As ubadub said, it seems like you're not actually telling us what you want to achieve.

If my guess that you're trying to save a field of bits is correct, you can make the whole thing very simple:

def get(self, arg1, arg2):
    return getattr(self, "var" + str(1+2*(1-arg2)+(1-arg1)))

But in that case, there are much better ways.

Upvotes: 1

dwanderson
dwanderson

Reputation: 2852

Not sure I fully grasp it; and if you're asking how to merge the get function with the set function, I don't think that makes sense (as formulated) - either you're setting values on an instance, or getting values that are already set.

class Something(object):

    def __init__(self, var1, var2, var3, var4):
        self.var1 = var1
        self.var2 = var2
        self.var3 = var3
        self.var4 = var4

    def getValue(self, chooseOdd, chooseFirst):
        if chooseOdd:
            choices = [self.var1, self.var3]
        else:
            choices = [self.var2, self.var4]
        index = 0 if chooseFirst else 1
        return choices[index]

But I might rather try something like:

class Something(object):
    def __init__(self, var1, var2, var3, var4):
        self.var1 = var1
        self.var2 = var2
        self.var3 = var3
        self.var4 = var4
        self.values = [var1, var2, var3, var4]

   def get(self, arg1, arg2):
       """ Either require, or manually convert, arg1, arg2 into 0, 1"""
       index = arg2 << 1 | arg1
       return self.values[index]

Upvotes: 0

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