Veek M <vek.m1...@gmail.com> writes: > Trying to make sense of that article. My understanding of debug was > simple: > 1. __debug__ is always True, unless -O or -OO > 2. 'if' is optimized out when True and the expr is inlined. > > So what does he mean by: > > 1. 'If you rebind __debug__, it can cause symptoms' > 2. 'During module compilation, the same code that handles literals also > handles the magic constants ..., None, True, False, and __debug__' > 3. 'you'll see that if __debug__: statements are either removed > entirely, or use LOAD_CONST to load the compile-time debug constant, > while if bool(__debug__): statements use LOAD_GLOBAL to load the value > of __debug__.' > > 4. 'Of course these are guaranteed to be the same… unless you rebind > __debug__' > > Basically every line in that answer is new to me..
It essentially tells you: "__debug__" has an internal use; only read it; never write (rebind) it. The rest are the details explaining what can go wrong when you write (rebind) "__debug__" and why. The "why" comes essentially from the fact that in some (but not all) cases "__debug__" is handled at compile time, while a potential writing it handled at runtime. Thus, after you have changed "__debug__", things may not work as you expect. If you keep in mind "do not change the value of __debug__ at runtime", you can forget all the details. -- https://mail.python.org/mailman/listinfo/python-list
