bearophile wrote:
It's hard to answer similar questions in an objective way. In Python 2.x the line continuation is implicit if you are inside a parenthesis: print (x + 5)
The trouble with that, from a language perspective, is what does the grammar look like? Since the newline is significant to parsing, it should be a token. But inside ( ), there's a problem with it being a token, because now the grammar is messed up by needing to accept an optional newline token in between any other two tokens - but only if inside ( ).
The obvious technical solution is to turn off recognition of newline tokens inside of ( ). This is characterized as "smart" parsing, but I have a less kind word for it - "hack" - because it means there's not a clean way to separate the lexer from the parser, and not a clean way to express the grammar.
From a language user's perspective this probably doesn't matter, but these kinds of things have a way of biting back in unanticipated nasty ways in the future. For example, C++'s use of < > for templates is a similar hack in the grammar. The C++ committee was warned at the time it was a very bad idea that would cause all kinds of problems, but they went ahead anyway because they thought it wouldn't affect users.
Turns out it did affect them, and it has caused a lot of grief over the years. There's another hack in C++0x in an attempt to paper over the problem.
