On 2006-09-13, Carl Banks <[EMAIL PROTECTED]> wrote: > metaperl wrote: >> --> python -i >> >>> class = "algebra" >> File "<stdin>", line 1 >> class = "algebra" >> ^ >> SyntaxError: invalid syntax >> >>> >> >> >> Why isn' t the parser smart enough to see that class followed by an >> identifier is used for class definition but class followed by equals is >> a simple assignment? > > Hmm. Someone called "metaPERL" is asking why Python doesn't have a > more complicated grammar. Why does this not surprise me? :)
Would a solution for this always make the grammer more complicated? > Seriously, Python is that way deliberately. The developers consider it > a good design to reserve keywords. It is not in any way considered a > flaw, nor an oversight, nor a case of laziness. > > Besides, what you ask is impossible in general. Consider this code: > > return(1,2,3) This is just an idea of mine, nothing I expect python to adapt. But just suppose the language allowed for words in bold. A word in bold would be considered a reserved word, a word in non bold would be an identifier. > Are you returning the tuple (1,2,3), or are you calling the function > "return" with arguments 1,2,3? There is no context-free grammar in the > universe that can divine which one is meant. It'd have to use context > to even guess, and in a highly dynamic language like Python, you can > never be wholly sure of the context. (Is there an identifier named > "return" in scope? Don't know until you run the code...) With my idea, you would just look whether "return" was written in bold or not. >> Also, I had a bug where I tried to set the attributes "user" and "pass" >> in an object but "pass" would not work because it is a reserved word. >> Again pass should be reserved in certain contexts but not others. >> >> Is Python 3k going to fix this sort of thing? > > Nope. PEP 3099 (which lists changes that won't be made in Python > 3000), states that the Python grammar will not be more complex than > LL(1), and says that simple grammars are more desirable than complex > ones. There is no hope of this being "fixed". This idea won't make python more complex than LL(1). -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
