2019-05-20 | Paul Boddie | raw annotate files changeset graph | Experiment with a temporary attribute on objects. This attribute must be cleared when assignments occur, but it should also be cleared when objects escape from functions (which is not yet done). Since the motivation for marking objects as temporary is their re-use in certain operations, the objective is to avoid objects being used in multiple places and still being marked as temporary and potentially undergoing re-use/mutation. Perhaps the only way of guaranteeing exclusive access to an object is if it is provided as a function result and is immediately passed to a function or operation, with this function either mutating the object or ensuring its direct propagation to another such function. | temporary-object-experiment |
1 class C: 2 def m(self): 3 return 1 4 5 D = C # alias for C 6 7 print C # __main__.C 8 print D # __main__.C 9 10 class E: 11 def m(self): 12 return 2 13 14 F = E # alias for E 15 16 print E # __main__.E 17 print F # __main__.E 18 19 def f(): 20 c = C 21 d = D # C 22 cm = C.m 23 dm = D.m # C.m 24 25 print c # __main__.C 26 print d # __main__.C 27 print cm # __main__.C.m 28 print dm # __main__.C.m 29 30 c = E 31 d = F # E 32 cm = E.m 33 dm = F.m # E.m 34 35 print c # __main__.E 36 print d # __main__.E 37 print cm # __main__.E.m 38 print dm # __main__.E.m 39 40 f() 41 42 Cm = C.m 43 Dm = D.m 44 Em = E.m 45 Fm = F.m 46 47 print Cm # __main__.C.m 48 print Dm # __main__.C.m 49 print Em # __main__.E.m 50 print Fm # __main__.E.m 51 52 def g(): 53 Cm = E.m 54 Dm = F.m # E.m 55 56 print Cm # __main__.E.m 57 print Dm # __main__.E.m 58 59 g() 60 61 def h(): 62 global Em, Fm 63 Em = C.m 64 Fm = D.m # C.m 65 66 print Em # __main__.C.m 67 print Fm # __main__.C.m 68 69 h() 70 71 print Em # __main__.C.m 72 print Fm # __main__.C.m 73 74 Ci = C() 75 Ei = E() 76 77 print Ci # <__main__.C instance> 78 print Ei # <__main__.E instance> 79 80 def i(): 81 c = Ci 82 print c # <__main__.C instance> 83 c = Ei 84 print c # <__main__.E instance> 85 86 i() 87 88 def j(): 89 global Ei 90 Ei = C() 91 print Ei # <__main__.C instance> 92 93 j() 94 95 print Ei # <__main__.C instance> 96 97 L = [] 98 M = [1] 99 100 print L # [] 101 print M # [1] 102 103 def k(): 104 c = L 105 print c # [] 106 107 k() 108 109 def l(): 110 global M 111 M = [] 112 print M # [] 113 114 l() 115 print M # []