[Python-3000] PEP-3125 -- remove backslash continuation

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> <HTML> <HEAD> <TITLE> [Python-3000] PEP-3125 -- remove backslash continuation </TITLE> <LINK REL="Index" HREF="index.html" > <LINK REL="made" HREF="mailto:python-3000%40python.org?Subject=%5BPython-3000%5D%20PEP-3125%20--%20remove%20backslash%20continuation&In-Reply-To=003601c78cbf%240cacec90%242606c5b0%24%40org"> <META NAME="robots" CONTENT="index,nofollow"> <META http-equiv="Content-Type" content="text/html; charset=us-ascii"> <LINK REL="Previous" HREF="007237.html"> <LINK REL="Next" HREF="007245.html"> </HEAD> <BODY BGCOLOR="#ffffff"> <H1>[Python-3000] PEP-3125 -- remove backslash continuation</H1> Guido van Rossum <A HREF="mailto:python-3000%40python.org?Subject=%5BPython-3000%5D%20PEP-3125%20--%20remove%20backslash%20continuation&In-Reply-To=003601c78cbf%240cacec90%242606c5b0%24%40org" TITLE="[Python-3000] PEP-3125 -- remove backslash continuation">guido at python.org </A> Wed May 2 20:15:04 CEST 2007 <UL> <LI>Previous message: <A HREF="007237.html">[Python-3000] PEP-3125 -- remove backslash continuation </A></li> <LI>Next message: <A HREF="007245.html">[Python-3000] PEP-3125 -- remove backslash continuation </A></li> <LI> Messages sorted by: <a href="date.html#7244">[ date ]</a> <a href="thread.html#7244">[ thread ]</a> <a href="subject.html#7244">[ subject ]</a> <a href="author.html#7244">[ author ]</a> </LI> </UL> <HR>  <PRE>On 5/2/07, Andrew Koenig <<A HREF="http://mail.python.org/mailman/listinfo/python-3000">ark at acm.org</A>> wrote: > Looking at PEP-3125, I see that one of the rejected alternatives is to allow > any unfinished expression to indicate a line continuation. > > I would like to suggest a modification to that alternative that has worked > successfully in another programming language, namely Stu Feldman's EFL. EFL > is a language intended for numerical programming; it compiles into Fortran > with the interesting property that the resulting Fortran code is intended to > be human-readable and maintainable by people who do not happen to have > access to the EFL compiler. > > Anyway, the (only) continuation rule in EFL is that if the last token in a > line is one that lexically cannot be the last token in a statement, then the > next line is considered a continuation of the current line. > > Python currently has a rule that if parentheses are unbalanced, a newline > does not end the statement. If we were to translate the EFL rule to Python, > it would be something like this: > > The whitespace that follows an operator or open bracket or > parenthesis > can include newline characters. > > Note that if this suggestion were implemented, it would presumably be at a > very low lexical level--even before the decision is made to turn a newline > followed by spaces into an INDENT or DEDENT token. I think that this > property solves the difficulty-of-parsing problem. Indeed, I think that > this suggestion would be easier to implement than the current > unbalanced-parentheses rule. > > Note also that like the current backslash rule, the space after the newline > would be just space, with no special significance. So to rewrite the > examples from the PEP: > > "abc" + # Plus is an operator, so it continues > "def" # The extra spaces before "def" do not constitute an > INDENT > > "abc" # Line does not end with an operator, so statement ends > + "def" # The newline and spaces constitute an INDENT -- this > is a syntax error > > ("abc" # I have no opinion about keeping the > unbalanced-parentheses rule -- > + "def") # but I do think that it is harder to parse (and also > harder to read) > # than what I am proposing. I am worried that (as no indent is required on the next line) it will accidentally introduce legal interpretations for certain common (?) typos, e.g. x = y+ # Used to be y+1, the 1 got dropped f(x) Still, if someone wants to give implementing this a try we could add this to the PEP. -- --Guido van Rossum (home page: <A HREF="http://www.python.org/~guido/">http://www.python.org/~guido/</A>) </PRE>  <HR> <UL>  <LI>Previous message: <A HREF="007237.html">[Python-3000] PEP-3125 -- remove backslash continuation </A></li> <LI>Next message: <A HREF="007245.html">[Python-3000] PEP-3125 -- remove backslash continuation </A></li> <LI> Messages sorted by: <a href="date.html#7244">[ date ]</a> <a href="thread.html#7244">[ thread ]</a> <a href="subject.html#7244">[ subject ]</a> <a href="author.html#7244">[ author ]</a> </LI> </UL> <hr> <a href="http://mail.python.org/mailman/listinfo/python-3000">More information about the Python-3000 mailing list</a> </body></html>

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[Python-3000] PEP-3125 -- remove backslash continuation