On Apr 24, 2018, at 2:10 PM, MRAB <python@mrabarnett.plus.com> wrote:
On 2018-04-21 03:15, Tim Peters wrote:
[Tim]
And I'll take this opportunity to repeat the key point for me: I tried hard, but never found a single case based on staring at real code where allowing _fancier_ (than "plain name") targets would be a real improvement. In every case I thought it _might_ help, it turned out that it really didn't unless Python _also_ grew an analog to C's "comma operator" (take only the last result from a sequence of expressions). I'll also note that I asked if anyone else had a real-life example, and got no responses.
[MRAB <python@mrabarnett.plus.com>]
Could a semicolon in a parenthesised expression be an equivalent to C's "comma operator"?
I expect it could, but I it's been many years since I tried hacking Python's grammar, and I wouldn't want a comma operator anyway ;-) [snip] Just reading this:
https://www.bfilipek.com/2018/04/refactoring-with-c17-stdoptional.html
about C++17, and what did I see? An example with a semicolon in parentheses!
A similar pattern shows up in Go's if statement syntax. It is interesting to note that it is part of the grammar specifically for the if statement and *not* general expression syntax. IfStmt = "if" [ SimpleStmt ";" ] Expression Block [ "else" ( IfStmt | Block ) ] . Bindings that occur inside of `SimpleStmt` are only available within the `Expression` and blocks that make up the if statement. https://golang.org/ref/spec#If_statements This isn't a good reason to parrot the syntax in Python though. IMO, I consider the pattern to be one of the distinguishing features of golang and would be happy leaving it there. I have often wondered if adding the venerable for loop syntax from C (and many other languages) would solve some of the needs here though. The for loop syntax in golang is interesting in that it serves as both a standard multipart for statement as well as a while statement. Changing something like this is more of a Python 4 feature and I think that I would be -0 on the concept. I did want to mention the similarities for the posterity though. ChrisA - we might want to add explicit mentions of golang's if statement and for loop as "considered" syntaxes since they are in a sibling programing language (e.g., similar to async/await in PEP 492). - dave -- "Syntactic sugar causes cancer of the semicolon" - Alan Perlis