class FloatValue:
    def __set_name__(self, cls, name):
        self.name = "_" + name

    def __get__(self, obj, cls):
        return getattr(obj, self.name)

    def __set__(self, obj, val):
        if type(val) != float:
            raise TypeError("Присваивать можно только вещественный тип данных.")
        setattr(obj, self.name, val)

class Cell:

    value = FloatValue()

    def __init__(self, value = 0.0):
        self.value = value

class TableSheet:
    def __init__ (self, N, M):
        self.cells = []
        for i in range(N):
            self.temp = []
            for j in range(M):
                self.temp.append(Cell())
            self.cells.append(self.temp)

table = TableSheet(5, 3)
counter = 1.0

for item in table.cells:
    for cell in item:
        cell = Cell(counter)
        counter += 1.0