2021-11-28 | Paul Boddie | file changeset files shortlog | Introduced support for values that can be allocated on a special thread-local stack, copied around and overwritten/mutated, demonstrating the concept using integer and floating-point numbers. Various complications arise with special attributes (such as __data__) due to the way references are tagged to indicate mutable values, and attribute slots must be cleared in locals, objects and fragments before values are stored since target slots are tested for mutable values. | tagged-address-values |
paul@601 | 1 | class C: |
paul@601 | 2 | def f(self): |
paul@601 | 3 | print self |
paul@601 | 4 | return self.value() |
paul@601 | 5 | |
paul@601 | 6 | def value(self): |
paul@601 | 7 | return 123 |
paul@601 | 8 | |
paul@601 | 9 | c = C() |
paul@601 | 10 | |
paul@601 | 11 | class D: |
paul@601 | 12 | f = c.f |
paul@601 | 13 | |
paul@601 | 14 | d = D() |
paul@601 | 15 | |
paul@853 | 16 | def fn(): |
paul@853 | 17 | return 456 |
paul@853 | 18 | |
paul@853 | 19 | class E: |
paul@853 | 20 | f = fn |
paul@853 | 21 | g = C.f |
paul@853 | 22 | |
paul@853 | 23 | e = E() |
paul@853 | 24 | |
paul@856 | 25 | # Normal method access and invocation. |
paul@856 | 26 | |
paul@601 | 27 | print c.f.__name__ # f |
paul@601 | 28 | print c.f() # <__main__.C instance> |
paul@601 | 29 | # 123 |
paul@856 | 30 | |
paul@856 | 31 | # Access and call assigned bound method. |
paul@856 | 32 | |
paul@601 | 33 | print d.f.__name__ # wrapper |
paul@601 | 34 | print d.f() # <__main__.C instance> |
paul@601 | 35 | # 123 |
paul@853 | 36 | |
paul@856 | 37 | # Access and call assigned function. |
paul@856 | 38 | |
paul@853 | 39 | print e.f.__name__ # fn |
paul@853 | 40 | print e.f() # 456 |
paul@856 | 41 | |
paul@856 | 42 | # Access details of assigned method. |
paul@856 | 43 | |
paul@853 | 44 | print e.g.__name__ # f |
paul@853 | 45 | |
paul@856 | 46 | # Attempt to call method belonging to another class via an incompatible |
paul@856 | 47 | # instance. In Python, this would be an unbound method call attempt. |
paul@856 | 48 | |
paul@853 | 49 | try: |
paul@853 | 50 | print e.g() |
paul@853 | 51 | except TypeError: |
paul@853 | 52 | print "e.g(): e is an incompatible instance for E.g which is C.f" |
paul@853 | 53 | |
paul@853 | 54 | g = get_using(E.g, c) |
paul@853 | 55 | print g.__name__ # f |
paul@853 | 56 | print g() # <__main__.C instance> |
paul@853 | 57 | # 123 |