marketplace.py

class Marketplace:
  def __init__(self):
    self.listings=[]
    
  def add_listing(self,new_listing):
    self.listings.append(new_listing)
  
  def remove_listing(self,item):
    self.listings.remove(item)
  
  def show_listings(self):
    for listing in self.listings:
      print(listing)
    
class Art:
  def __init__(self,artist,title,medium,year,owner):
    self.artist=artist
    self.title=title
    self.medium=medium
    self.year=year
    self.owner=owner
    
  def __repr__(self):
    return "{artist}. \"{title}\". {year}, {medium}, {name}, {location}.".format(artist=self.artist, title=self.title, year=self.year, medium=self.medium, name=self.owner.name, location=self.owner.location)
  
class Listing:
  def __init__(self,art,price,seller):
    self.art=art
    self.price=price
    self.seller=seller
    
  def __repr__(self):
    return "{art} ,{price}.".format(art=self.art,price=self.price)
  
class Client:
  def __init__(self,name,location,is_museum):
    self.name = name
    self.location=location
    self.is_museum=is_museum
    
  def sell_artwork(self,artwork,price):
    if self == artwork.owner:
      new_listing=Listing (artwork,price,self)
      veneer.add_listing(new_listing)
  
  def buy_artwork(self,artwork):
    if artwork.owner != self:
      art_listing =None
      for listing in veneer.listings:
        if listing.art == artwork:
          art_listing=listing
          break
      if art_listing!= None:
        art_listing.art.owner = self
        veneer.remove_listing(art_listing)
    
    
    
###################################
veneer=Marketplace()

edytta = Client("Edytta Halpirt","Private Collection", False)

moma = Client("The MOMA","New York", True)

girl_with_mandolin= Art("Picasso, Pablo","Girl with a Mandolin (Fanny Tellier)","oil on canvas",1910,edytta)

edytta.sell_artwork(girl_with_mandolin, "$6M (USD)")

veneer.show_listings()
moma.buy_artwork(girl_with_mandolin)
print(girl_with_mandolin)
veneer.show_listings()