Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

Steven D'Aprano writes: > What key combination do I need to type to get ≜ in the following editors > please? I tried typing \triangleq but all I got was \triangleq. Your implied point is correct IMO, but all of the editors and applications mentioned that I've used are perfectly happy with any

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Tue, Apr 17, 2018 at 03:36:34AM +1000, Chris Angelico wrote: [further aggressive snippage] *wink* > > Chris, I must admit that I'm utterly perplexed at this. Your example is > > as far as from a complex assignment target as you can possibly get. It's > > a simple name! > > > > i := i + 1

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

> Hey! I did not propose "?". Read the explanation in parenthesis. > My whole idea that any option could be viable, as long as > it does not propose reversed order notation. Dear Mikhail, so sorry about my misunderstanding, I should read the post with fewer presuppositions... Back to the topic,

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Tue, Apr 17, 2018 at 6:09 AM, Thautwarm Zhao wrote: > > > 3) "target ? expr" (where ? is some other word/character - IIRC > > "target from expr" was proposed once) > > A more popular convention is to mark `?` as handling boolean variables, so > `target ? expr`

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Mon, Apr 16, 2018 at 8:09 PM, Thautwarm Zhao wrote: > > > 3) "target ? expr" (where ? is some other word/character - IIRC > > "target from expr" was proposed once) > > A more popular convention is to mark `?` as handling boolean variables, so > `target ? expr` could

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

> We have ways of cheating a bit if we want to reinterpret the semantics > of something that nevertheless parses cleanly - while the parser is > limited to single token lookahead, it's straightforward for the > subsequent code generation stage to look a single level down in the > parse tree and

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Mon, Apr 16, 2018 at 11:11 AM Ned Batchelder wrote: > On 4/16/18 1:42 PM, Chris Angelico wrote: > > 3) "expr -> name" ==> The information went data way. > > > > So either you take a parallel from elsewhere in Python syntax, or you > > take a hopefully-intuitive

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Tue, Apr 17, 2018 at 5:11 AM, Steve Barnes wrote: > >> Here are the three most popular syntax options, and how each would be >> explained: >> >> 1) "target := expr" ==> It's exactly the same as other forms of >> assignment, only now it's an expression. >> 2) "expr as

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On 4/16/18 1:42 PM, Chris Angelico wrote: 3) "expr -> name" ==> The information went data way. So either you take a parallel from elsewhere in Python syntax, or you take a hopefully-intuitive dataflow mnemonic symbol. Take your pick. My problem with the "->" option is that function

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On 04/16/2018 10:36 AM, Chris Angelico wrote: Not after it got trimmed, no. Here's what I actually said in my original post: while (read_next_item() -> items[i + 1 -> i]) is not None: print("%d/%d..." % (i, len(items)), end="\r") Now, if THAT is your assignment target, are you still as

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Mon, Apr 16, 2018 at 11:05 PM, Mikhail V wrote: > Lets just return to some of proposed examples > (I use "=" in both examples to be less biased here): > > 1. > if ( match = re.match("foo", S) ) == True: > print("match:", match) > > 2. > if ( re.match("foo", S) =

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On 16 April 2018 at 00:27, Thautwarm Zhao wrote: > Personally I prefer "as", but I think without a big change of python Grammar > file, it's impossible to avoid parsing "with expr as name" into "with (expr > as name)" because "expr as name" is actually an "expr". > I have

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Mon, Apr 16, 2018 at 06:16:46AM +1000, Chris Angelico wrote: [...] > >> >>> items = [None] * 10 > >> >>> i = -1 > >> >>> items[i := i + 1] = input("> ") > >> > asdf > >> >>> items[i := i + 1] = input("> ") > >> > qwer > >> >>> items[i := i + 1] = input("> ") > >> > zxcv > >> >>> > >> >>> items

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Sun, Apr 15, 2018 at 6:58 PM, Steven D'Aprano wrote: > On Sun, Apr 15, 2018 at 10:21:02PM +1000, Chris Angelico wrote: > >> I don't think we're ever going to unify everyone on an arbitrary >> question of "expression first" or "name first". But to all the >> "expression

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

[Guido] 2018-04-15 20:19 GMT+03:00 Guido van Rossum : > On Sun, Apr 15, 2018 at 4:05 AM, Kirill Balunov > wrote: > >> [...] For me personally, `: =` looks and feels just like normal >> assignment statement which can be used interchangeable but in many

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

2018-04-15 23:22 GMT+03:00 Chris Angelico : > > > 0. > > > > while (items[i := i+1] := read_next_item()) is not None: > > print(r'%d/%d' % (i, len(items)), end='\r') > > > > 1. > > > > while (read_next_item() -> items[(i+1) -> i]) is not None: > > print(r'%d/%d' % (i,

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On 2018-04-15 08:58, Steven D'Aprano wrote: I've been mulling over the question why I think the expression needs to come first here, whereas I'm satisfied with the target coming first for assignment statements, and I think I've finally got the words to explain it. It is not just long familiarity

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Mon, Apr 16, 2018 at 4:58 AM, Thautwarm Zhao wrote: > Dear Steve, I'm sorry to annoy you by my proposal, but I do think using > unicode might be wise in current stage. > > \triangleq could be print with unicode number \u225c, and adding plugins to > support typing this

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Sun, Apr 15, 2018 at 2:01 PM, Nick Coghlan wrote: > On 15 April 2018 at 19:41, Mikhail V wrote: >> So IIUC, the *only* reason is to avoid '==' ad '=' similarity? >> If so, then it does not sound convincing at all. >> Of course Python does me a favor

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Mon, Apr 16, 2018 at 3:19 AM, Guido van Rossum wrote: > On Sun, Apr 15, 2018 at 4:05 AM, Kirill Balunov > wrote: >> But somehow this PEP does not mean it! And with the current rationale of >> this PEP it's a huge CON for me that `=` and `:=` feel and

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Mon, Apr 16, 2018 at 12:17 AM, Kirill Balunov wrote: > > > 2018-04-15 15:21 GMT+03:00 Chris Angelico : >> I don't think we're ever going to unify everyone on an arbitrary >> question of "expression first" or "name first". But to all the >> "expression

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Mon, Apr 16, 2018 at 1:58 AM, Steven D'Aprano wrote: > On Sun, Apr 15, 2018 at 10:21:02PM +1000, Chris Angelico wrote: > >> I don't think we're ever going to unify everyone on an arbitrary >> question of "expression first" or "name first". But to all the >> "expression

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

2018-04-15 18:58 GMT+03:00 Steven D'Aprano : > > [...] > > But this time we don't care about the name. Its the value we care about: > > result = some_func(don't care, >don't care -> don't care >don't care -> don't care >

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Sun, Apr 15, 2018 at 11:11:37PM +0800, Thautwarm Zhao wrote: > I think maybe we can use unicode characters like ≜ (\triangleq) and add the > support of unicode completion to python repl. The unicode completion of > editors or ides has been quite mature. What key combination do I need to type

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Sun, Apr 15, 2018 at 10:21:02PM +1000, Chris Angelico wrote: > I don't think we're ever going to unify everyone on an arbitrary > question of "expression first" or "name first". But to all the > "expression first" people, a question: what if the target is not just > a simple name? > > while

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

> > > 0. > > while (items[i := i+1] := read_next_item()) is not None: > print(r'%d/%d' % (i, len(items)), end='\r') > > 1. > > while (read_next_item() -> items[(i+1) -> i]) is not None: > print(r'%d/%d' % (i, len(items)), end='\r') > > 2. > > while (item := read_next_item()) is not None: >

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

> To me, "from" strongly suggests that an element is being obtained from a container/collection of > elements. This is how I conceptualize "from module import name": "name" refers to an object > INSIDE the module, not the module itself. If I saw > > if (match from pattern.search(data)) is not

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

2018-04-15 15:21 GMT+03:00 Chris Angelico : > On Sun, Apr 15, 2018 at 7:19 PM, Kirill Balunov > wrote: > >> === Expression first, 'as' keyword === > >> > >> while (read_next_item() as value) is not None: > >> ... > >> > >> Pros: > >> > >>

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Sun, Apr 15, 2018 at 7:19 PM, Kirill Balunov wrote: >> === Expression first, 'as' keyword === >> >> while (read_next_item() as value) is not None: >> ... >> >> Pros: >> >> * typically reads nicely as pseudocode >> * "as" is already associated with

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

2018-04-15 12:41 GMT+03:00 Mikhail V : > > Exactly, all forms invites this and other questions. > > First of all, coming back to original spelling choice arguments > [Sorry in advance if I've missed some points in this huge thread] > > citation from PEP: > "Differences

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On 15 April 2018 at 19:41, Mikhail V wrote: > So IIUC, the *only* reason is to avoid '==' ad '=' similarity? > If so, then it does not sound convincing at all. > Of course Python does me a favor showing an error, > when I make a typo like this: > if (x = y) > > But still, if

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Sun, Apr 15, 2018 at 12:19 PM, Kirill Balunov wrote: > > > 2018-04-15 6:08 GMT+03:00 Nick Coghlan : >> >> > >> >> P.S. The pros and cons of the current syntax proposals, as I see them: >> >> === Expression first, 'as' keyword === >> >> while

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

2018-04-15 6:08 GMT+03:00 Nick Coghlan : > > It's not completely off topic. as it's due to the fact we use "," to > separate both context managers and items in a tuple, so "with (cm1, > cm2, cm3):" is currently legal syntax that means something quite > different from "with

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On 15 April 2018 at 13:54, Chris Angelico wrote: > On Sun, Apr 15, 2018 at 1:08 PM, Nick Coghlan wrote: >> === Target first, 'from' keyword === >> >> while (value from read_next_item()) is not None: # New >> ... >> >> Pros: >> >> * avoids the

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Sat, Apr 14, 2018 at 11:54 PM, Chris Angelico wrote: > On Sun, Apr 15, 2018 at 1:08 PM, Nick Coghlan wrote: > > === Target first, 'from' keyword === > > > > while (value from read_next_item()) is not None: # New > > ... > > > > Pros: > > > >

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On 04/14/2018 08:08 PM, Nick Coghlan wrote: New keyword based target first proposal: while (value from read_next_item()) is not None: ... I could get behind this. Current preferencs: "as" +1 "from" +0.85 ":=" +0.5 -- ~Ethan~

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Sun, Apr 15, 2018 at 1:08 PM, Nick Coghlan wrote: > === Target first, 'from' keyword === > > while (value from read_next_item()) is not None: # New > ... > > Pros: > > * avoids the syntactic ambiguity of "as" > * being target first provides an obvious

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On 13 April 2018 at 23:18, Steven D'Aprano wrote: > On Fri, Apr 13, 2018 at 09:56:35PM +1000, Chris Angelico wrote: > > >> How many times have people asked for "with (expr as name):" to >> be supported, allowing the statement to spread over multiple lines? >> With this

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Apr 14 2018, Chris Angelico wrote: > On Fri, Apr 13, 2018 at 11:30 PM, Peter O'Connor > wrote: >> Well this may be crazy sounding, but we could allow left or right assignment >> with >>

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Sat, Apr 14, 2018 at 7:33 AM, Kirill Balunov wrote: > > > 2018-04-13 23:31 GMT+03:00 Chris Angelico : >> >> >> > # but these are subtly different and will be a trap for the unwary >> > with expression as name: # name is set to __enter__() >>

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Fri, Apr 13, 2018 at 11:30 PM, Peter O'Connor wrote: > Well this may be crazy sounding, but we could allow left or right assignment > with > > name := expr > expr =: name > > Although it would seem to violate the "only one obvious way" maxim, at least > it avoids

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Fri, Apr 13, 2018 at 05:04:00PM +0200, Jacco van Dorp wrote: > > I'm saying, don't even try to distinguish between the forms with or > > without parens. If we add parens: > > > > with (expr as name): > > > > it may or may not be allowed some time in the future (since it isn't > > allowed

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On 04/13/2018 05:02 AM, Jacco van Dorp wrote: I must admit I like putting the expression first, though. Even if it's just to make it harder to mix it up with normal assignment. Perhaps => could be used - it's a new token, unlike -> which is used to annotate return values, it's not legal syntax

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

Well this may be crazy sounding, but we could allow left or right assignment with name := expr expr =: name Although it would seem to violate the "only one obvious way" maxim, at least it avoids this overloaded meaning with the "as" of "except" and "with" On Fri, Apr 13, 2018 at 9:29 AM,

Re: [Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Fri, Apr 13, 2018 at 9:04 PM, Steven D'Aprano wrote: > On Wed, Apr 11, 2018 at 03:32:04PM +1000, Chris Angelico wrote: > >> In any context where arbitrary Python expressions can be used, a **named >> expression** can appear. This can be parenthesized for clarity, and is of

[Python-ideas] Spelling of Assignment Expressions PEP 572 (was post #4)

On Wed, Apr 11, 2018 at 03:32:04PM +1000, Chris Angelico wrote: > In any context where arbitrary Python expressions can be used, a **named > expression** can appear. This can be parenthesized for clarity, and is of > the form ``(target := expr)`` where ``expr`` is any valid Python expression, >