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Corrected version.
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wizzwizz4
wizzwizz4
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import code import dis import sys class Bool(int): __slots__ = () _last_code = None _last_offset = None _last_target = None # absolute def __bool__(self): frame = sys._getframe(1) ##code.inspectinteract(local = locals()) # enable for development   for instinsts in= dis.get_instructions(frame.f_code) for inst in insts: if inst.offset == frame.f_lasti: break else: inst = None # fallback if inst and inst.opname == 'JUMP_IF_FALSE_OR_POP': target = inst.argval result = False elif inst and inst.opname == 'JUMP_IF_TRUE_OR_POP': target = next(inst).offset result = True else: target = Nonefloat('NaN') xand = (Bool._last_code is frame.f_code and Bool._last_offset != frame.f_lasti and Bool._last_target == target ) Bool._last_code = frame.f_code Bool._last_offset = frame.f_lasti Bool._last_target = target if xand: return Falseresult return super().__bool__() def __repr__(self): return "TRUE" if self else "FALSE" TRUE = Bool(1) FALSE = Bool(0) Bool.__new__ = lambda cls, x: TRUE if x else FALSE 
>>> if TRUE: ... print("Hello, world!") ... Hello, world! >>> if TRUE and TRUE: ... print("Goodbye, world!") ... >>> import random >>> a = b = TRUE >>> while TRUE: ... i = random.randint(0, 2) ... if i == 0 and a: ... print("a") ... elif i == 1 and b: ... print("b") ... elif i == 2 and not (a and b): ... print("but not at the same time") b a a a b b KeyboardInterrupt >>>

This approach should work in everything from Python 3.1 to Python 3.10. It won't work in Python 3.11+, thanks to the compiler revamp, but they didn't re-use the opcode names so adding support should be easy enough. (Just take care not to mix up relative and absolute jump offsets.)

It needs JUMP_FORWARD support to handle if FALSE: pass else: ..., and JUMP_ABSOLUTE support to handle if at the end of while loops, but I grow tired of this program.

import code import dis import sys class Bool(int): __slots__ = () _last_code = None _last_offset = None _last_target = None # absolute def __bool__(self): frame = sys._getframe(1) ##code.inspect(local = locals()) # enable for development   for inst in dis.get_instructions(frame.f_code): if inst.offset == frame.f_lasti: break else: inst = None # fallback if inst and inst.opname == 'JUMP_IF_FALSE_OR_POP': target = inst.argval else: target = None xand = (Bool._last_code is frame.f_code and Bool._last_offset != frame.f_lasti and Bool._last_target == target ) Bool._last_code = frame.f_code Bool._last_offset = frame.f_lasti Bool._last_target = target if xand: return False return super().__bool__() def __repr__(self): return "TRUE" if self else "FALSE" TRUE = Bool(1) FALSE = Bool(0) Bool.__new__ = lambda cls, x: TRUE if x else FALSE 
>>> if TRUE: ... print("Hello, world!") ... Hello, world! >>> if TRUE and TRUE: ... print("Goodbye, world!") ... >>> import random >>> a = b = TRUE >>> while TRUE: ... i = random.randint(0, 2) ... if i == 0 and a: ... print("a") ... elif i == 1 and b: ... print("b") ... elif i == 2 and a and b: ... print("but not at the same time") b a a a b b KeyboardInterrupt >>>

This approach should work in everything from Python 3.1 to Python 3.10. It won't work in Python 3.11+, thanks to the compiler revamp, but they didn't re-use the opcode names so adding support should be easy enough. (Just take care not to mix up relative and absolute jump offsets.)

import code import dis import sys class Bool(int): __slots__ = () _last_code = None _last_offset = None _last_target = None # absolute def __bool__(self): frame = sys._getframe(1) ##code.interact(local = locals()) # enable for development insts = dis.get_instructions(frame.f_code) for inst in insts: if inst.offset == frame.f_lasti: break else: inst = None # fallback if inst and inst.opname == 'JUMP_IF_FALSE_OR_POP': target = inst.argval result = False elif inst and inst.opname == 'JUMP_IF_TRUE_OR_POP': target = next(inst).offset result = True else: target = float('NaN') xand = (Bool._last_code is frame.f_code and Bool._last_offset != frame.f_lasti and Bool._last_target == target ) Bool._last_code = frame.f_code Bool._last_offset = frame.f_lasti Bool._last_target = target if xand: return result return super().__bool__() def __repr__(self): return "TRUE" if self else "FALSE" TRUE = Bool(1) FALSE = Bool(0) Bool.__new__ = lambda cls, x: TRUE if x else FALSE 
>>> if TRUE: ... print("Hello, world!") ... Hello, world! >>> if TRUE and TRUE: ... print("Goodbye, world!") ... >>> import random >>> a = b = TRUE >>> while TRUE: ... i = random.randint(0, 2) ... if i == 0 and a: ... print("a") ... elif i == 1 and b: ... print("b") ... elif i == 2 and not (a and b): ... print("but not at the same time") b a a a b b KeyboardInterrupt >>>

This approach should work in everything from Python 3.1 to Python 3.10. It won't work in Python 3.11+, thanks to the compiler revamp, but they didn't re-use the opcode names so adding support should be easy enough. (Just take care not to mix up relative and absolute jump offsets.)

It needs JUMP_FORWARD support to handle if FALSE: pass else: ..., and JUMP_ABSOLUTE support to handle if at the end of while loops, but I grow tired of this program.

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wizzwizz4
wizzwizz4
  • 2.5k
  • 18
  • 44

Python 3.9

import code import dis import sys class Bool(int): __slots__ = () _last_code = None _last_offset = None _last_target = None # absolute def __bool__(self): frame = sys._getframe(1) ##code.inspect(local = locals()) # enable for development for inst in dis.get_instructions(frame.f_code): if inst.offset == frame.f_lasti: break else: inst = None # fallback if inst and inst.opname == 'JUMP_IF_FALSE_OR_POP': target = inst.argval else: target = None xand = (Bool._last_code is frame.f_code and Bool._last_offset != frame.f_lasti and Bool._last_target == target ) Bool._last_code = frame.f_code Bool._last_offset = frame.f_lasti Bool._last_target = target if xand: return False return super().__bool__() def __repr__(self): return "TRUE" if self else "FALSE" TRUE = Bool(1) FALSE = Bool(0) Bool.__new__ = lambda cls, x: TRUE if x else FALSE

Demonstration

>>> if TRUE: ... print("Hello, world!") ... Hello, world! >>> if TRUE and TRUE: ... print("Goodbye, world!") ... >>> import random >>> a = b = TRUE >>> while TRUE: ... i = random.randint(0, 2) ... if i == 0 and a: ... print("a") ... elif i == 1 and b: ... print("b") ... elif i == 2 and a and b: ... print("but not at the same time") b a a a b b KeyboardInterrupt >>>

Remarks

When writing Python code, it's important to adhere to PEP 8 – Style Guide for Python Code:

  • Class names should normally use the CapWords convention.

  • Constants are usually defined on a module level and written in all capital letters with underscores separating words.

This approach should work in everything from Python 3.1 to Python 3.10. It won't work in Python 3.11+, thanks to the compiler revamp, but they didn't re-use the opcode names so adding support should be easy enough. (Just take care not to mix up relative and absolute jump offsets.)