Hi, 2011/5/18 Terry Reedy <tjre...@udel.edu>: > On 5/18/2011 10:19 AM, Nadeem Vawda wrote: > >> I'm not sure why you would encounter code like that in the first place. >> Surely any code of the form: >> >> ''.join(c for c in my_string) >> >> would just return my_string? Or am I missing something? > > Good question. Anything useful like "'-'.join(c for c in 'abc')" is the same > as "'-'.join('abc'). The same, as far as I can think of, for anything like > list() or set() taking an iterable arg.
With a little imagination you can build something non trivial. For example, a join_words function: def join_words(words): return ', '.join(w.strip() for w in words) Like Victor says, the code of the generator object contains a STORE_FAST followed by LOAD_FAST. This pair of opcodes could be removed, and the value left on the stack. >>> dis.dis(join_words.func_code.co_consts[2]) 1 0 SETUP_LOOP 24 (to 27) 3 LOAD_FAST 0 (.0) >> 6 FOR_ITER 17 (to 26) 9 STORE_FAST 1 (w) 12 LOAD_FAST 1 (w) 15 LOAD_ATTR 0 (strip) 18 CALL_FUNCTION 0 21 YIELD_VALUE 22 POP_TOP 23 JUMP_ABSOLUTE 6 >> 26 POP_BLOCK >> 27 LOAD_CONST 0 (None) 30 RETURN_VALUE It's probably not easy to do though. Think of expressions where the variable appears several times, or even where the variable is not the first object, like str(ord(x)). -- Amaury Forgeot d'Arc _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com