function - Operator Overloading in Python coming from C++ -


i'm trying overload operators in python class represents mathematical fraction. in particular i'm trying overload * operator can have fraction * fraction, fraction * integer , integer * fraction operations. i've had experience c++ , in case write operator overloads in fraction class:

friend fraction operator*(const fraction &f1, const fraction &f2); friend fraction operator*(const fraction &f, int v); friend fraction operator*(int v, const fraction &f);

my understanding c++ knows function resolve based on arguments give it. since in python function parameters aren't typed i'm confused how python knows operator overload resolve to? example:

def __mul__(self, other):     return fraction(self.numerator * other.numerator, self.denominator * other.denominator)  def __mul__(self,value):     return fraction(self.numerator * value,self.denominator)

the first overload work 2 fractions , second fraction , integer, how python know use? i'm new python although i've been using c++ while.

python won't resolve functions type @ all. can have one method named __mul__ begin with; not multiple versions of method different signatures. have type resolution hand inside 1 method if necessary:

def __mul__(self, other):     if isinstance(other, int):         ...

note it's pythonic duck-type as possible, might want check hasattr(other, 'numerator') instead of strict isinstance checks.


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