On Aug 10, 1:37 am, Steven D'Aprano <ste...@remove.this.cybersource.com.au> wrote: > On Mon, 10 Aug 2009 00:37:33 -0700, Carl Banks wrote: > > On Aug 9, 11:10 pm, Steven D'Aprano > > <ste...@remove.this.cybersource.com.au> wrote: > >> On Sun, 09 Aug 2009 18:34:14 -0700, Carl Banks wrote: > >> >> Why should a backslash in a string literal be an error? > > >> > Because the behavior of \ in a string is context-dependent, which > >> > means a reader can't know if \ is a literal character or escape > >> > character without knowing the context, and it means an innocuous > >> > change in context can cause a rather significant change in \. > > >> *Any* change in context is significant with escapes. > > >> "this \nhas two lines" > > >> If you change the \n to a \t you get a significant difference. If you > >> change the \n to a \y you get a significant difference. Why is the > >> first one acceptable but the second not? > > > Because when you change \n to \t, you've haven't changed the meaning of > > the \ character; > > I assume you mean the \ character in the literal, not the (non-existent) > \ character in the string. > > > but when you change \n to \y, you have, and you did so > > without even touching the backslash. > > Not at all. > > '\n' maps to the string chr(10). > '\y' maps to the string chr(92) + chr(121). > > In both cases the backslash in the literal have the same meaning: grab > the next token (usually a single character, but not always), look it up > in a mapping somewhere, and insert the result in the string object being > built.
That is a ridiculous rationalization. Nobody sees "\y" in a string and thinks "it's an escape sequence that returns the bytes '\y'". [snip rest, because an argument in favor inconsistent, context- dependent behavior doesn't need any further refutation than to point out that it is an argument in favor of inconsistent, context-dependent behavior] Carl Banks -- http://mail.python.org/mailman/listinfo/python-list
