Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[G. P. B.]

Hello Internals,

Round 2, I'm planning to open voting tomorrow, the only change being is
handling of string digits to behave like doing an ASCII string range:
https://wiki.php.net/rfc/proper-range-semantics

Any final comments or complaints should be raised now.

Best regards,

George P. Banyard

Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[G. P. B.]

On Tue, 16 May 2023 at 17:49, Jorg Sowa  wrote:

> Thank you. That makes sense. I have last question about case with integer
> and string digit, i.e. range('5', 10) or range('1', 9). What would be in
> this case expected output? I couldn't find any test cases covering this
> example.
>

I've added test cases, but the RFC already mentions that those numeric
strings would be interpreted as integers and thus generate a list of ints.

Best regards,

George P. Banyard

PS: Just an etiquette reminder to bottom post instead of top posting to not
carry around the previous bits of emails (see
https://github.com/Danack/RfcCodex/blob/master/etiquette/mailing_list.md#why-should-i-place-my-response-below-the-quoted-text
)

Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[Jorg Sowa]

Thank you. That makes sense. I have last question about case with integer
and string digit, i.e. range('5', 10) or range('1', 9). What would be in
this case expected output? I couldn't find any test cases covering this
example.

Kind regards,
Jorg

On Tue, May 16, 2023 at 2:29 PM G. P. B.  wrote:

> On Mon, 15 May 2023 at 23:53, Jorg Sowa  wrote:
>
>> Hello!
>>
>> I have one concern about the part:
>>
>> > Emit an E_WARNING when $start or $end is cast to an integer because
>> the other boundary input is a number or numeric string. (e.g. range
>> ('5', 'z'); or range 
>> (5, 'z');)
>>
>> Doesn't it limit the functionality of the function for the numbers as
>> characters? Currently when we call range('/','z') we get full range of
>> characters. https://onlinephp.io/c/9cb12
>>
>> But when we change argument $start to next character which is zero ('0')
>> then we get array with only one element. https://onlinephp.io/c/a0cda
>>
>> Casting numerical string in this function may be confusing.
>>
>> Sorry for making fuss just before voting, but didn't see this topic
>> before and wanted to share my insights with you thinking it may be relevant.
>>
>
> No worries, this is the point of giving a heads-up.
> Someone else brought this to my attention again as well.
> And the concern makes sense, I've updated the implementation and RFC to
> adjust the behaviour with string digits:
> https://wiki.php.net/rfc/proper-range-semantics
>
> Please let me know if this addresses the issue and is also clear.
>
> Best regards,
>
> George P. Banyard
>
>
>
>

Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[G. P. B.]

On Mon, 15 May 2023 at 23:53, Jorg Sowa  wrote:

> Hello!
>
> I have one concern about the part:
>
> > Emit an E_WARNING when $start or $end is cast to an integer because the
> other boundary input is a number or numeric string. (e.g. range
> ('5', 'z'); or range (
> 5, 'z');)
>
> Doesn't it limit the functionality of the function for the numbers as
> characters? Currently when we call range('/','z') we get full range of
> characters. https://onlinephp.io/c/9cb12
>
> But when we change argument $start to next character which is zero ('0')
> then we get array with only one element. https://onlinephp.io/c/a0cda
>
> Casting numerical string in this function may be confusing.
>
> Sorry for making fuss just before voting, but didn't see this topic before
> and wanted to share my insights with you thinking it may be relevant.
>

No worries, this is the point of giving a heads-up.
Someone else brought this to my attention again as well.
And the concern makes sense, I've updated the implementation and RFC to
adjust the behaviour with string digits:
https://wiki.php.net/rfc/proper-range-semantics

Please let me know if this addresses the issue and is also clear.

Best regards,

George P. Banyard

Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[Jorg Sowa]

Hello!

I have one concern about the part:

> Emit an E_WARNING when $start or $end is cast to an integer because the
other boundary input is a number or numeric string. (e.g. range
('5', 'z'); or range (5,
'z');)

Doesn't it limit the functionality of the function for the numbers as
characters? Currently when we call range('/','z') we get full range of
characters. https://onlinephp.io/c/9cb12

But when we change argument $start to next character which is zero ('0')
then we get array with only one element. https://onlinephp.io/c/a0cda

Casting numerical string in this function may be confusing.

Sorry for making fuss just before voting, but didn't see this topic before
and wanted to share my insights with you thinking it may be relevant.

Kind regards,
Jorg

On Mon, May 15, 2023 at 4:42 PM G. P. B.  wrote:

> Hello Internals,
>
> I plan to put the RFC to a vote tomorrow in its current state, which has
> not been changed since the 30th of March:
> https://wiki.php.net/rfc/proper-range-semantics
>
> Any final comments or complaints should be raised now.
>
> Best regards,
>
> George P. Banyard
>

Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[G. P. B.]

Hello Internals,

I plan to put the RFC to a vote tomorrow in its current state, which has
not been changed since the 30th of March:
https://wiki.php.net/rfc/proper-range-semantics

Any final comments or complaints should be raised now.

Best regards,

George P. Banyard

Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[G. P. B.]

On Fri, 5 May 2023 at 15:49, Derick Rethans  wrote:

> On Mon, 27 Mar 2023, G. P. B. wrote:
>
> > While working on analysing the impact of the changes proposed by
> > amending the behaviour of the increment and decrement operators (
> > https://wiki.php.net/rfc/saner-inc-dec-operators) I discovered that
> > the range() function has some rather lax behaviour that is very
> > unintuitive.
> >
> > I therefore propose the "Define proper semantics for range() function"
> > RFC to address the unintuitive behaviour that sees no usage and/or
> > hide bugs: https://wiki.php.net/rfc/proper-range-semantics
>
> | If $step is a float but is compatible with int interpret it as an
> | integer.
>
> I guess you mean with that "the fraction is '.0'" and "-2^52 < number <
> 2^52" ? What is also going to be playing up is the range of $start and
>
$end itself.
>

Yes, this is what I mean by "compatible with int".


> | Introduce and use a proper ZPP check for int|float|string $start and
> | $end parameters, this will cause TypeErrors to be thrown when passing
> | objects, resources, and arrays to range().
>
> I am not sure whether it wise to disallow resources. These are often
> file descriptors and having a range on those *could* make sense? Not
> fussed much either way though.
>

This is not how file/stream resources work. The resource number is not
correlated to the file descriptor.
The only cases where this is the case are the predefined streams STDIN,
STDOUT, and STDERR.
This is part of the reason for needing a new function like the
file_descriptor() function I'm proposing. [1]


> | Throw a ValueError when passing a negative $step for increasing
> | ranges.
>
> I think that's a BC break that is not worthy of making.
>

There is no impact shown, and it doesn't make sense to pass a negative
$step.
This can be changed to a deprecation but considering there is no impact I
don't see why we should wait.

| Emit an E_WARNING when $start or $end has more than one byte.
>
> Surely only if the string doesn't represent an int or float?
>

Yes, this was implied. As we are only concerned about the "pure string"
case here.
But I have clarified this.

| var_dump(range(null, 2));
>
> I think that safely can be interpreted as range(0, 2) — I wouldn't throw
> a deprecation warning for that... but then of course, we do already have
> a similar (deprecation) warning for arguments.
>

The deprecation is just a consequence of finally using ZPP, thus invoking
the previously accepted RFC.


> > The change propose to throw TypeErrors and ValueErrors for case where I
> > couldn't find occurrences in the wild and hide bugs, and emit some
> > E_WARNINGs for cases that are hard to detect via static analysis.
>
> | Target Version: PHP 8.3
>
> In my opinion that's not a good thing. There are a fair amount of BC
> breaks (beyond the one that I oppose to with nagative steps throwing an
> ValyeError), without first having deprecations. IMO, the actual BC
> breaks here should become deprecations in 8.X and BC can only be really
> broken in 9.0.


Disagree, the implementation is already complicated, and trying to support
the current absurd behaviour is impractical, especially as no impact has
been found.

Best regards,

George P. Banyard

[1] https://wiki.php.net/rfc/file-descriptor-function

Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[Derick Rethans]

On Mon, 27 Mar 2023, G. P. B. wrote:

> While working on analysing the impact of the changes proposed by 
> amending the behaviour of the increment and decrement operators ( 
> https://wiki.php.net/rfc/saner-inc-dec-operators) I discovered that 
> the range() function has some rather lax behaviour that is very 
> unintuitive.
> 
> I therefore propose the "Define proper semantics for range() function" 
> RFC to address the unintuitive behaviour that sees no usage and/or 
> hide bugs: https://wiki.php.net/rfc/proper-range-semantics

| If $step is a float but is compatible with int interpret it as an 
| integer.

I guess you mean with that "the fraction is '.0'" and "-2^52 < number < 
2^52" ? What is also going to be playing up is the range of $start and 
$end itself. 

| Introduce and use a proper ZPP check for int|float|string $start and 
| $end parameters, this will cause TypeErrors to be thrown when passing 
| objects, resources, and arrays to range(). 

I am not sure whether it wise to disallow resources. These are often 
file descriptors and having a range on those *could* make sense? Not 
fussed much either way though.

| Throw a ValueError when passing a negative $step for increasing 
| ranges.

I think that's a BC break that is not worthy of making. 

| Emit an E_WARNING when $start or $end has more than one byte.

Surely only if the string doesn't represent an int or float?

| var_dump(range(null, 2));

I think that safely can be interpreted as range(0, 2) — I wouldn't throw 
a deprecation warning for that... but then of course, we do already have 
a similar (deprecation) warning for arguments.

> 
> The change propose to throw TypeErrors and ValueErrors for case where I
> couldn't find occurrences in the wild and hide bugs, and emit some
> E_WARNINGs for cases that are hard to detect via static analysis.

| Target Version: PHP 8.3

In my opinion that's not a good thing. There are a fair amount of BC 
breaks (beyond the one that I oppose to with nagative steps throwing an 
ValyeError), without first having deprecations. IMO, the actual BC 
breaks here should become deprecations in 8.X and BC can only be really 
broken in 9.0.

cheers,
Derick

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Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[Kamil Tekiela]

>
> I've changed the behaviour to throw a ValueError if a negative step is
> provided with increasing range and accept negative steps for decreasing
> ranges.
>

I am not sure this is better. This would introduce a BC break because now
it's not as easy to avoid the error as you can't just wrap the variable in
abs() call.
I am not sure why we are even treating this as an error. It looks to me
like PHP already copes with this whether it's a positive or negative
number. If we just want to inform the user that the sign has no meaning, we
can raise a Notice and leave it at that. It's not wrong that the step is
negative, it's just a pointless sign.

Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[G. P. B.]

On Thu, 30 Mar 2023 at 03:50, Mark Baker  wrote:

> On 28/03/2023 00:36, G. P. B. wrote:
> > Hello internals,
> >
> > While working on analysing the impact of the changes proposed by amending
> > the behaviour of the increment and decrement operators (
> > https://wiki.php.net/rfc/saner-inc-dec-operators) I discovered that the
> > range() function has some rather lax behaviour that is very unintuitive.
> >
> > I therefore propose the "Define proper semantics for range() function"
> RFC
> > to address the unintuitive behaviour that sees no usage and/or hide bugs:
> > https://wiki.php.net/rfc/proper-range-semantics
> >
> > The change propose to throw TypeErrors and ValueErrors for case where I
> > couldn't find occurrences in the wild and hide bugs, and emit some
> > E_WARNINGs for cases that are hard to detect via static analysis.
>
> Unlike your changes to the increment operator, I'd love to see this
> rationalisation put in place, though like many here I don't see problems
> with using a negative step with decreasing ranges, but would consider it
> strange for increasing ranges.


I still find it somewhat odd, but this is not a hill I'm going to die on.
I've changed the behaviour to throw a ValueError if a negative step is
provided with increasing range and accept negative steps for decreasing
ranges.
Furthermore, I've also made passing an empty string an E_WARNING with a
cast to 0, same as the current behaviour.

See new version:
https://wiki.php.net/rfc/proper-range-semantics


> And I do want to see some
> case-consistency when working with string ranges.
>
>
> I'd love to see it taken a stage (or two) further; returning an iterable
> rather than an array (although that would be a bc break); and working
> with strings (ASCII only) in the same way that the increment operator
> does, so that range('A', 'IV') would be valid, and return `Z` then `AA`,
> `AZ` then `BA`, etc.
>

Frankly I was also surprised that the behaviour with strings was to do an
ASCII code point increment.
As I would agree that range("Y", "AC") returning ["Y", "Z", "AA", "AB",
"AC"] would have been more intuitive than the silently discarding
everything past the 1st byte.
However, I don't think there is much point in breaking BC to return a
possible generator or fix the unfortunate string behaviour.
I would rather that PHP creates dedicated syntax to creates ranges (e.g.
$s..$e seems to be what most other programming languages settles on,
although it might be slightly confused as concatenation) à la Ruby which
allows objects that implement certain methods to also be used to generate
ranges.
This is IMHO way more powerful as it would allow the creation of Date
ranges or other custom ranges.
And part of this proposal could be to support the aforementioned
alphabetical string ranges natively without needing to break BC on range()
and let this function just fade away into obscurity.

There is also this C++ talk from over a decade ago that argues that Ranges
are better than iterator, so this might be an additional motivation as to
why we would want this:
https://accu.org/conf-docs/PDFs_2009/AndreiAlexandrescu_iterators-must-go.pdf


> I am slightly surprised that you make no mention of the odd behaviour of
> mixed alphameric strings, e.g. var_dump(range('A1', 'C5')) which returns
> a purely alpha array 'A' to 'C'; or var_dump(range('3c', '5e')) which
> returns numeric (3, 4, 5); or var_dump(range('1', '1e2')) which treates
> `1e2` as scientific and returns 1..100.
>

Because I didn't think of this and was just well usual numeric string
behaviour or non-numeric string behaviour that truncates the string.
But that range('3c', '5e') is the only way to get an array of digits as
strings, and it makes me want to shout into the abyss.
I'm not sure it super worth to mention those cases, but I can add examples
of this to the RFC after crying about the even more insane behaviour
range() currently has.

Best regards,

George P. Banyard

Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[Mark Baker]

On 28/03/2023 00:36, G. P. B. wrote:

Hello internals,

While working on analysing the impact of the changes proposed by amending
the behaviour of the increment and decrement operators (
https://wiki.php.net/rfc/saner-inc-dec-operators) I discovered that the
range() function has some rather lax behaviour that is very unintuitive.

I therefore propose the "Define proper semantics for range() function" RFC
to address the unintuitive behaviour that sees no usage and/or hide bugs:
https://wiki.php.net/rfc/proper-range-semantics

The change propose to throw TypeErrors and ValueErrors for case where I
couldn't find occurrences in the wild and hide bugs, and emit some
E_WARNINGs for cases that are hard to detect via static analysis.


Unlike your changes to the increment operator, I'd love to see this 
rationalisation put in place, though like many here I don't see problems 
with using a negative step with decreasing ranges, but would consider it 
strange for increasing ranges. And I do want to see some 
case-consistency when working with string ranges.



I'd love to see it taken a stage (or two) further; returning an iterable 
rather than an array (although that would be a bc break); and working 
with strings (ASCII only) in the same way that the increment operator 
does, so that range('A', 'IV') would be valid, and return `Z` then `AA`, 
`AZ` then `BA`, etc.



I am slightly surprised that you make no mention of the odd behaviour of 
mixed alphameric strings, e.g. var_dump(range('A1', 'C5')) which returns 
a purely alpha array 'A' to 'C'; or var_dump(range('3c', '5e')) which 
returns numeric (3, 4, 5); or var_dump(range('1', '1e2')) which treates 
`1e2` as scientific and returns 1..100.


--
Mark Baker

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Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[Niels Dossche]

Hi

On 28/03/2023 14:42, G. P. B. wrote:
> On Tue, 28 Mar 2023 at 08:19, Christian Schneider 
> wrote:
> 
>> Am 28.03.2023 um 00:36 schrieb G. P. B. :
>>> I therefore propose the "Define proper semantics for range() function"
>> RFC
>>> to address the unintuitive behaviour that sees no usage and/or hide bugs:
>>> https://wiki.php.net/rfc/proper-range-semantics
>>>
>>> The change propose to throw TypeErrors and ValueErrors for case where I
>>> couldn't find occurrences in the wild and hide bugs, and emit some
>>> E_WARNINGs for cases that are hard to detect via static analysis.
>>
>> I think it makes sense to clean up the range() function, thanks!
>>
>> There are two cases I would handle differently:
>> - I'm not sure why a negative step for $start > $end is considered wrong,
>> I consider range(10, 0, -2) at least as logical/readable as using a
>> positive decrement of 2. Not requiring a sign for steps seems weirder to me
>> but that's something we cannot change. *BUT* if it is the result of a
>> calculation it seems wrong to require an abs() around it. I do see the
>> reason for a warning/error when $start < $end and $step < 0.
>>
> 
> Considering the only other programming language that I know of that has a
> range() function that accepts a step argument is Python, and its behaviour
> is IMHO worse.
> For increasing ranges it requires a positive step, and if not just
> generates an empty range.
> For decreasing ranges it requires a negative step, and if not just
> generates an empty range (this applies even if using the default step value
> of 1 which is bonkers).
> 
> Making it a requirement to pass a negative step is definitely out of the
> question.
> Making it okay to use negative steps *only* for decreasing ranges could be
> sensible, but we check for the step parameter way before we look into the
> boundary values because those are different for int, float and string
> boundaries.
> Moreover, I personally find it weirder to require a sign for negative steps
> as for me a step is something that *must* be positive, and at least Kotlin
> seems to somewhat agree with me looking around at
> https://kotlinlang.org/docs/ranges.html#progression and playing with the
> source code
> Namely:
> for (i in 4 downTo 1 step 2) print(i)
> 
>> 42
> 
> for (i in 4 downTo 1 step -2) print(i)
> 
>> Exception in thread "main" java.lang.IllegalArgumentException: Step must
> be positive, was: -2.
> 
> 
>> - Values of '' or null in integer context (e.g. range(null, 10, 2)) should
>> IMHO emit a warning first, not directly be changed to a TypeError. The
>> usual BC / migration concern :-)
>>
> 
> When null is used, no TypeError is emitted, just the "usual" null to scalar
> deprecation that happens since
> https://wiki.php.net/rfc/deprecate_null_to_scalar_internal_arg got accepted.
> But I'll add an example to the RFC and a test case in the PR.
> 
> Trying to figure out if an empty string was used with another string
> boundary is tedious, as this information needs to somehow get carried
> around.
> A previous iteration of the PR used to convert empty strings to 0 with a
> warning, but considering the analysis I decide to just make this a
> ValueError as it doesn't seem that empty strings are actually used in
> practice.
> But this is an easy revert, and I'm not really bound to this decision.
> 
> Best regards,
> 
> George P. Banyard
> 

I like the RFC in general, just this negative $step parameter warning stood out 
to me.

While I agree that requiring a negative $step for a decreasing range is a bit 
silly,
I've always found it intuitive that a negative $step should be used for a 
decreasing range.
I'm not saying that it should be required, I'm just concerned about the BC 
break of emitting E_WARNING and breaking people's intuition.

The reasoning behind this is that range($start, $end, $step) (for me at least) 
has always been symmetric and consistent with a for loop:
  $array = [];
  for ($i = $start; $i < $end (or >); $i += $step) { $array[] = $i; }
So by allowing a negative step the behaviour is consistent with how for loops 
behave, and avoids a BC break.

That Kotlin doesn't require it makes sense for me because the words "down to" 
combined with a negative step indeed don't make sense.
The negativity is in a sense already embedded by explicitly writing "down to". 
It's less explicit for PHP's range function.

I looked at the source code of some of my projects and I do see some 
occurrences of range($high, $low, -1 (or another negative value)).

Just wanted to chime in quickly to state my thoughts on this.
Thanks.

Kind regards
Niels

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Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[Christian Schneider]

Am 28.03.2023 um 14:42 schrieb G. P. B. :
> On Tue, 28 Mar 2023 at 08:19, Christian Schneider  
> wrote:
>> There are two cases I would handle differently:
>> - I'm not sure why a negative step for $start > $end is considered wrong, I 
>> consider range(10, 0, -2) at least as logical/readable as using a positive 
>> decrement of 2. Not requiring a sign for steps seems weirder to me but 
>> that's something we cannot change. *BUT* if it is the result of a 
>> calculation it seems wrong to require an abs() around it. I do see the 
>> reason for a warning/error when $start < $end and $step < 0.
>> 
> Considering the only other programming language that I know of that has a 
> range() function that accepts a step argument is Python, and its behaviour is 
> IMHO worse.
> For increasing ranges it requires a positive step, and if not just generates 
> an empty range. For decreasing ranges it requires a negative step, and if not 
> just generates an empty range (this applies even if using the default step 
> value of 1 which is bonkers).
> 
> Making it a requirement to pass a negative step is definitely out of the 
> question.
> Making it okay to use negative steps *only* for decreasing ranges could be 
> sensible, but we check for the step parameter way before we look into the 
> boundary values because those are different for int, float and string 
> boundaries.
> Moreover, I personally find it weirder to require a sign for negative steps 
> as for me a step is something that *must* be positive

I quickly checked our own codebase and there is indeed one instance of
range($last, 0, -1)
which was not written by me so there is at least one more person who found this 
logical ;-)

>>  - Values of '' or null in integer context (e.g. range(null, 10, 2)) should 
>> IMHO emit a warning first, not directly be changed to a TypeError. The usual 
>> BC / migration concern :-)
> 
> Trying to figure out if an empty string was used with another string boundary 
> is tedious, as this information needs to somehow get carried around.
> A previous iteration of the PR used to convert empty strings to 0 with a 
> warning, but considering the analysis I decide to just make this a ValueError 
> as it doesn't seem that empty strings are actually used in practice.
> But this is an easy revert, and I'm not really bound to this decision.

Even though this might be a bit cumbersome at the moment I think this would be 
an important transition step as currently
range('', 10, 2);
returns the (somewhat) expected result of 0, 2, 4, 6, 8, 10 so I'd be in favor 
of first giving a warning and then changing it to a ValueError.

- Chris

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Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[G. P. B.]

On Tue, 28 Mar 2023 at 08:29, Tim Düsterhus  wrote:

> Hi
>
> On 3/28/23 00:36, G. P. B. wrote:
> > I therefore propose the "Define proper semantics for range() function"
> RFC
> > to address the unintuitive behaviour that sees no usage and/or hide bugs:
> > https://wiki.php.net/rfc/proper-range-semantics
>
> The "ASCII code point range" example is confusing, because it is a
> decreasing range. However decreasing ranges are only introduced in the
> next example.
>
> Best regards
> Tim Düsterhus
>

I've reordered the example and added a more descriptive ASCII code point
range example first!

I've also added an example which highlights the behaviour with null and how
it would emits deprecation notices.

Best regards,

George P. Banyard

Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[G. P. B.]

On Tue, 28 Mar 2023 at 08:19, Christian Schneider 
wrote:

> Am 28.03.2023 um 00:36 schrieb G. P. B. :
> > I therefore propose the "Define proper semantics for range() function"
> RFC
> > to address the unintuitive behaviour that sees no usage and/or hide bugs:
> > https://wiki.php.net/rfc/proper-range-semantics
> >
> > The change propose to throw TypeErrors and ValueErrors for case where I
> > couldn't find occurrences in the wild and hide bugs, and emit some
> > E_WARNINGs for cases that are hard to detect via static analysis.
>
> I think it makes sense to clean up the range() function, thanks!
>
> There are two cases I would handle differently:
> - I'm not sure why a negative step for $start > $end is considered wrong,
> I consider range(10, 0, -2) at least as logical/readable as using a
> positive decrement of 2. Not requiring a sign for steps seems weirder to me
> but that's something we cannot change. *BUT* if it is the result of a
> calculation it seems wrong to require an abs() around it. I do see the
> reason for a warning/error when $start < $end and $step < 0.
>

Considering the only other programming language that I know of that has a
range() function that accepts a step argument is Python, and its behaviour
is IMHO worse.
For increasing ranges it requires a positive step, and if not just
generates an empty range.
For decreasing ranges it requires a negative step, and if not just
generates an empty range (this applies even if using the default step value
of 1 which is bonkers).

Making it a requirement to pass a negative step is definitely out of the
question.
Making it okay to use negative steps *only* for decreasing ranges could be
sensible, but we check for the step parameter way before we look into the
boundary values because those are different for int, float and string
boundaries.
Moreover, I personally find it weirder to require a sign for negative steps
as for me a step is something that *must* be positive, and at least Kotlin
seems to somewhat agree with me looking around at
https://kotlinlang.org/docs/ranges.html#progression and playing with the
source code
Namely:
for (i in 4 downTo 1 step 2) print(i)

> 42

for (i in 4 downTo 1 step -2) print(i)

> Exception in thread "main" java.lang.IllegalArgumentException: Step must
be positive, was: -2.


> - Values of '' or null in integer context (e.g. range(null, 10, 2)) should
> IMHO emit a warning first, not directly be changed to a TypeError. The
> usual BC / migration concern :-)
>

When null is used, no TypeError is emitted, just the "usual" null to scalar
deprecation that happens since
https://wiki.php.net/rfc/deprecate_null_to_scalar_internal_arg got accepted.
But I'll add an example to the RFC and a test case in the PR.

Trying to figure out if an empty string was used with another string
boundary is tedious, as this information needs to somehow get carried
around.
A previous iteration of the PR used to convert empty strings to 0 with a
warning, but considering the analysis I decide to just make this a
ValueError as it doesn't seem that empty strings are actually used in
practice.
But this is an easy revert, and I'm not really bound to this decision.

Best regards,

George P. Banyard

Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[Tim Düsterhus]

Hi

On 3/28/23 00:36, G. P. B. wrote:

I therefore propose the "Define proper semantics for range() function" RFC
to address the unintuitive behaviour that sees no usage and/or hide bugs:
https://wiki.php.net/rfc/proper-range-semantics


The "ASCII code point range" example is confusing, because it is a 
decreasing range. However decreasing ranges are only introduced in the 
next example.


Best regards
Tim Düsterhus

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Re: [PHP-DEV] [RFC] Define proper semantics for range() function

[Christian Schneider]

Am 28.03.2023 um 00:36 schrieb G. P. B. :
> I therefore propose the "Define proper semantics for range() function" RFC
> to address the unintuitive behaviour that sees no usage and/or hide bugs:
> https://wiki.php.net/rfc/proper-range-semantics
> 
> The change propose to throw TypeErrors and ValueErrors for case where I
> couldn't find occurrences in the wild and hide bugs, and emit some
> E_WARNINGs for cases that are hard to detect via static analysis.

I think it makes sense to clean up the range() function, thanks!

There are two cases I would handle differently:
- I'm not sure why a negative step for $start > $end is considered wrong, I 
consider range(10, 0, -2) at least as logical/readable as using a positive 
decrement of 2. Not requiring a sign for steps seems weirder to me but that's 
something we cannot change. *BUT* if it is the result of a calculation it seems 
wrong to require an abs() around it. I do see the reason for a warning/error 
when $start < $end and $step < 0.
- Values of '' or null in integer context (e.g. range(null, 10, 2)) should IMHO 
emit a warning first, not directly be changed to a TypeError. The usual BC / 
migration concern :-)

Regards,
- Chris

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