Proposal for deprecate alternate syntax(curly braces) for array and string access View as Markdown

Reasons to deprecate curly braces syntax::

1.  Two ways to do the same thing.
   

2.  It is very rarely used nowadays.
   

3.  It is almost not documented. There is only two short “NOTE” about 
   

it.

4.  Also, this syntax has reduced functionality. You can't use it for 
   

pushing element into array “$arr{} = 1;”, creating array “$a={1,2};” or in
other similar cases.

5.  Deprecation and following removal will free this syntax for other 
   

features. For example: array/string slice, absolute offset access,
“windows” (like “slice” in GoLang), etc.

Proposal
https://wiki.php.net/rfc/deprecate_curly_braces_array_access

Patch diff
https://github.com/php/php-src/compare/PHP-7.4...rjhdby:deprecate_alternate_array_access

Migration script
https://github.com/rjhdby/php-src/blob/deprecate_alternate_array_access/convert_array_access_braces.php

Reasons to deprecate curly braces syntax::

1.  Two ways to do the same thing.
   

2.  It is very rarely used nowadays.
   

3.  It is almost not documented. There is only two short “NOTE” about 
   

it.

4.  Also, this syntax has reduced functionality. You can't use it for 
   

pushing element into array “$arr{} = 1;”, creating array “$a={1,2};” or in
other similar cases.

5.  Deprecation and following removal will free this syntax for other 
   

features. For example: array/string slice, absolute offset access,
“windows” (like “slice” in GoLang), etc.

Proposal
https://wiki.php.net/rfc/deprecate_curly_braces_array_access

Do I understand it right, that you're proposing deprecating accessing
$string{$offset}? I think that's an important way of differentiation
between string and array offset access.

I'd vote "yes" for splitting syntax on array and string offset access,
but as is: -1.

Patch diff
https://github.com/php/php-src/compare/PHP-7.4...rjhdby:deprecate_alternate_array_access

Migration script
https://github.com/rjhdby/php-src/blob/deprecate_alternate_array_access/convert_array_access_braces.php

--
Regards,
Mike

Reasons to deprecate curly braces syntax::

1.  Two ways to do the same thing.
   

2.  It is very rarely used nowadays.
   

3.  It is almost not documented. There is only two short “NOTE” about
   

it.

4.  Also, this syntax has reduced functionality. You can't use it for
   

pushing element into array “$arr{} = 1;”, creating array “$a={1,2};” or in
other similar cases.

5.  Deprecation and following removal will free this syntax for other
   

features. For example: array/string slice, absolute offset access,
“windows” (like “slice” in GoLang), etc.

Proposal
https://wiki.php.net/rfc/deprecate_curly_braces_array_access

Patch diff

https://github.com/php/php-src/compare/PHP-7.4...rjhdby:deprecate_alternate_array_access

Migration script

https://github.com/rjhdby/php-src/blob/deprecate_alternate_array_access/convert_array_access_braces.php

I'm okay with this. This syntax has already been deprecated once, though it
was reverted for reasons I don't remember.

There are some people using this syntax to distinguish between array and
string access. It's a nice thought, but as the vast majority of code
doesn't make this distinction (I think the only time I saw this in recent
years was inside some old PEAR code), it's not really a useful indicator.
The rarity of its use also makes it rather confusing. While $foo[$x] is
well established as an array or string offset (or for that matter,
ArrayObject) access and will be recognized by any programmer coming from
any number of programming languages, $foo{$x} certainly is not, and is a
WTF moment for people who don't happen to personally use this syntax.

I'd prefer to phase out this syntax entirely and not reuse it for any other
purpose. Reusing syntax is generally a not so good idea, because it means
that the same syntax has different meaning in different PHP version.

Nikita

Den fre. 15. mar. 2019 kl. 17.06 skrev Nikita Popov nikita.ppv@gmail.com:

I'm okay with this. This syntax has already been deprecated once, though it
was reverted for reasons I don't remember.

There are some people using this syntax to distinguish between array and
string access. It's a nice thought, but as the vast majority of code
doesn't make this distinction (I think the only time I saw this in recent
years was inside some old PEAR code), it's not really a useful indicator.

I personally use it because I like to quickly tell if I am doing an
operation on a string or array, it is eye candy and makes a lot of
sense. I think if anything the two syntaxes should be decoupled
instead.

From a usage PoV, then from personal experience (outside my own
projects), I have seen many usages of this syntax, even as late as my
current company with a growing codebase that is nearing 1.1m LoC, I
have seen this syntax used countless of times. In fact I don't think I
have been working with a code base where I have not seen this syntax
used.

I have asked fellow developers around in my community today and they
have no strong opinion on either, but do like the distinction between.

The rarity of its use also makes it rather confusing. While $foo[$x] is
well established as an array or string offset (or for that matter,
ArrayObject) access and will be recognized by any programmer coming from
any number of programming languages, $foo{$x} certainly is not, and is a
WTF moment for people who don't happen to personally use this syntax.

I'd prefer to phase out this syntax entirely and not reuse it for any other
purpose. Reusing syntax is generally a not so good idea, because it means
that the same syntax has different meaning in different PHP version.

For me personally it is a huge -1, if anything I would like the
string[] syntax decoupled.

--
regards,

Kalle Sommer Nielsen
kalle@php.net

Den fre. 15. mar. 2019 kl. 17.06 skrev Nikita Popov nikita.ppv@gmail.com:

I'm okay with this. This syntax has already been deprecated once, though it
was reverted for reasons I don't remember.

There are some people using this syntax to distinguish between array and
string access. It's a nice thought, but as the vast majority of code
doesn't make this distinction (I think the only time I saw this in recent
years was inside some old PEAR code), it's not really a useful indicator.

I personally use it because I like to quickly tell if I am doing an
operation on a string or array, it is eye candy and makes a lot of
sense. I think if anything the two syntaxes should be decoupled
instead.

From a usage PoV, then from personal experience (outside my own
projects), I have seen many usages of this syntax, even as late as my
current company with a growing codebase that is nearing 1.1m LoC, I
have seen this syntax used countless of times. In fact I don't think I
have been working with a code base where I have not seen this syntax
used.

I have asked fellow developers around in my community today and they
have no strong opinion on either, but do like the distinction between.

The rarity of its use also makes it rather confusing. While $foo[$x] is
well established as an array or string offset (or for that matter,
ArrayObject) access and will be recognized by any programmer coming from
any number of programming languages, $foo{$x} certainly is not, and is a
WTF moment for people who don't happen to personally use this syntax.

I'd prefer to phase out this syntax entirely and not reuse it for any other
purpose. Reusing syntax is generally a not so good idea, because it means
that the same syntax has different meaning in different PHP version.

For me personally it is a huge -1, if anything I would like the
string[] syntax decoupled.

--
regards,

Kalle Sommer Nielsen
kalle@php.net

--

Four thoughts:

1. I cannot think of any reason to separate them. If you want to
   make sure you are indexing a string, do a type check, not bake {}
   into only working on strings.
2. While Kalle says pretty much every codebase they've seen lately
   has used {} for indexing, I have never seen a codebase that used
   it.
3. In any case, usage of {} can be migrated to [] by a style
   fixer, right?
4. Even if we deprecate {}, I don't think we'd be in any hurry to
   remove it, though with an automatic fixer this seems doable, if we
   care to do it at all.

1. I cannot think of any reason to separate them. If you want to
   make sure you are indexing a string, do a type check, not bake {}
   into only working on strings.

I think it's more common to do the opposite: think you're working on an
array, and accidentally pick up a string.

If we separated the syntaxes, it would be possible to always raise a
warning when that happens, rather than silently returning the Nth character.

To be honest I can't remember the last time I used either syntax for
string access, other than by accident.

Regards,

Rowan Collins
[IMSoP]

Den fre. 15. mar. 2019 kl. 19.53 skrev Levi Morrison levim@php.net:

Four thoughts:

1. I cannot think of any reason to separate them. If you want to
   make sure you are indexing a string, do a type check, not bake {}
   into only working on strings.
2. While Kalle says pretty much every codebase they've seen lately
   has used {} for indexing, I have never seen a codebase that used
   it.

Well maybe that happens to be just me, not a huge amount of usages but
there is usually some.

3. In any case, usage of {} can be migrated to [] by a style
   fixer, right?
4. Even if we deprecate {}, I don't think we'd be in any hurry to
   remove it, though with an automatic fixer this seems doable, if we
   care to do it at all.

The thing is, I just don't understand the rationale to remove this
feature, what the full gain from doing so is?

--
regards,

Kalle Sommer Nielsen
kalle@php.net

There are some people using this syntax to distinguish between array
and
string access. It's a nice thought, but as the vast majority of code
doesn't make this distinction (I think the only time I saw this in
recent
years was inside some old PEAR code), it's not really a useful
indicator.

I personally use it because I like to quickly tell if I am doing an
operation on a string or array, it is eye candy and makes a lot of
sense. I think if anything the two syntaxes should be decoupled
instead.

I think that suitable naming is more useful for this purpose.
As this syntax used both for arrays and strings then "$a{2}"
says absolutely nothing to anybody instead author, maybe.

The thing is, I just don't understand the rationale to remove this
feature, what the full gain from doing so is?

I'm fully agree with Nikita Popov:

The rarity of its use also makes it rather confusing. While $foo[$x]
is well established as an
array or string offset (or for that matter, ArrayObject) access and
will be
recognized by any programmer coming from any number of programming
languages,
$foo{$x} certainly is not, and is a WTF moment for people who don't
happen to personally
use this syntax.

Furthermore, curly braces is standard way to separate scope in almost
all languages including PHP (except one very rare and special case).

@Michael Wallner

Do I understand it right, that you're proposing deprecating accessing
$string{$offset}? I think that's an important way of differentiation
between string and array offset access.

I'd vote "yes" for splitting syntax on array and string offset access,
but as is: -1.

When we access char inside string, actually we access
to element of indexed array of chars.

Splitting array and string access is complex change.
For now it processed on AST-creation phase and it is possible
to transfer to compiler via AST-attribute. For splitting
it is needs to transfer this difference into runtime.

In addition, this separation can lead to much more ambiguity when
migrating old code.