Hello list,
I found this RFC, describing a feature I wanted for a long time:
https://wiki.php.net/rfc/list_default_value
https://marc.info/?l=php-internals&m=144707619509724
(I don't know how to correctly reply to old emails that are not in my
inbox, sorry for that. I don't like mailing lists.)
I regularly want this kind of feature when unpacking a string with explode():
list($prefix, $suffix = NULL) = explode(':', $string);
if (NULL !== $suffix) {
...
}
This is for situations where a string is coming from somewhere, we
hope it has the format "aaa:bbb", but we cannot be sure.
Sometimes I use a workaround like this:
list($prefix, $suffix) = explode(':', $string . ':');
if ('' !== $suffix) {
...
}
Which works, but means a new string will be allocated in memory.
I find the list() with default values to be a decent and
understandable language feature.
-- Andreas
I don't have a strong opinion about the nested list() construct which
is also part of the RFC.
I never had a situation where I wanted this.
Hello list,
I found this RFC, describing a feature I wanted for a long time:
https://wiki.php.net/rfc/list_default_value
https://marc.info/?l=php-internals&m=144707619509724(I don't know how to correctly reply to old emails that are not in my
inbox, sorry for that. I don't like mailing lists.)I regularly want this kind of feature when unpacking a string with
explode():list($prefix, $suffix = NULL) = explode(':', $string);
if (NULL !== $suffix) {
...
}This is for situations where a string is coming from somewhere, we
hope it has the format "aaa:bbb", but we cannot be sure.Sometimes I use a workaround like this:
list($prefix, $suffix) = explode(':', $string . ':');
if ('' !== $suffix) {
...
}
Which works, but means a new string will be allocated in memory.I find the list() with default values to be a decent and
understandable language feature.-- Andreas
I found this RFC, describing a feature I wanted for a long time:
https://wiki.php.net/rfc/list_default_value
https://marc.info/?l=php-internals&m=144707619509724I regularly want this kind of feature when unpacking a string with
explode():list($prefix, $suffix = NULL) = explode(':', $string);
if (NULL !== $suffix) {
...
}
Agreed. This comes up for me every time I want to parse a text file
(including about 30 minutes ago, as it happens).
+1
-Sara
Would isset($suffix) not suffice here? There are several things I've
thought of that would be other alternatives to changing this language
construct, but as I don't have my laptop with me, some of the testing to
confirm behavior will have to wait.
Other concerns fall around list() already being a difficult thing for
people to understand, let alone use properly. Making it look even more like
a function definition would likely exacerbate this.
-Chris
On Thu, Aug 10, 2017 at 5:21 PM, Andreas Hennings andreas@dqxtech.net
wrote:
I found this RFC, describing a feature I wanted for a long time:
https://wiki.php.net/rfc/list_default_value
https://marc.info/?l=php-internals&m=144707619509724I regularly want this kind of feature when unpacking a string with
explode():list($prefix, $suffix = NULL) = explode(':', $string);
if (NULL !== $suffix) {
...
}
Agreed. This comes up for me every time I want to parse a text file
(including about 30 minutes ago, as it happens).
+1
-Sara
Would isset($suffix) not suffice here?
You mean like so?
list($prefix, $suffix) = explode(':', 'string_without_suffix');
if (!isset($suffix)) {
..
}
The isset() is too late here, because the list() will already cause an error.
Other concerns fall around list() already being a difficult thing for people to understand
I fail to understand what is difficult about it..
And "destructuring" is a common concept in programming languages.
https://www.startpage.com/do/search?query=destructuring&cat=web&pl=chrome&language=english
https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment
The following already works in Javascript:
[a, b, c, d = 'else'] = ['aa', 'bb', 'cc'];
I just tried it in my Chromium console.
"Andreas Hennings" wrote in message
news:CAH0Uv3HQK5wjcd_-9GynMw34H78ZTv09q9bc=yZ10JBbeT=VOA@mail.gmail.com...
On Fri, Aug 11, 2017 at 12:01 AM, Devnuhl Unnamed devnuhl@gmail.com
wrote:Would isset($suffix) not suffice here?
You mean like so?
list($prefix, $suffix) = explode(':', 'string_without_suffix');
if (!isset($suffix)) {
..
}The isset() is too late here, because the list() will already cause an
error.Other concerns fall around list() already being a difficult thing for
people to understand
I agree.
I fail to understand what is difficult about it.
The point is that other people have difficulty understanding what is
supposed to be a simple feature which is now being expanded to include more
options which change its behaviour.
And "destructuring" is a common concept in programming languages.
https://www.startpage.com/do/search
?query=destructuring&cat=web&pl=chrome&language=english
https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Operators/Destructuring_assignmentThe following already works in Javascript:
[a, b, c, d = 'else'] = ['aa', 'bb', 'cc'];
I just tried it in my Chromium console.
That fact that something like this exists in another language is no reason
to add it to PHP.
--
Tony Marston
When you understand something, it often can be hard to understand why
others wouldn't. I don't see why people struggle with it either, but I do
see it happen quite a lot.
I would still think that if you are going to deconstruct something in a
structured way, you should validate your data is correct beforehand. And
that would be the more ideal solution here. But if replies to a genuine
concern over things I've witnessed is going to be met with a dismissive
attitude, I'm just going to bow out entirely.
Chris
On Fri, Aug 11, 2017 at 12:01 AM, Devnuhl Unnamed devnuhl@gmail.com
wrote:Would isset($suffix) not suffice here?
You mean like so?
list($prefix, $suffix) = explode(':', 'string_without_suffix');
if (!isset($suffix)) {
..
}The isset() is too late here, because the list() will already cause an
error.Other concerns fall around list() already being a difficult thing for
people to understandI fail to understand what is difficult about it..
And "destructuring" is a common concept in programming languages.
https://www.startpage.com/do/search?query=destructuring&;
cat=web&pl=chrome&language=english
https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Operators/
Destructuring_assignmentThe following already works in Javascript:
[a, b, c, d = 'else'] = ['aa', 'bb', 'cc'];
I just tried it in my Chromium console.
You can merge the result with default values like this:
[$foo, $bar, $foobar] = explode(':', 'foo:bar') + [23, 42, 1337];
var_dump($foo, $bar, $foobar);
This is true, I remember having done it in the past.
I still think it would be nice and feel natural to have the default
values directly built into the list construct.
It would be a bit faster, because it does not have to allocate a new
temporary array.
Whether this difference matters depends on the case.
In my own philosophy, every code that I write to be reusable, could at
some point be used in a situation where it is repeated a lot, and thus
has a performance impact. So for my taste, it does matter.
This said, I understand it not having the greatest priority.
You can merge the result with default values like this:
[$foo, $bar, $foobar] = explode(':', 'foo:bar') + [23, 42, 1337];
var_dump($foo, $bar, $foobar);
Den 2017-08-12 kl. 02:37, skrev Andreas Hennings:
This is true, I remember having done it in the past.
I still think it would be nice and feel natural to have the default
values directly built into the list construct.It would be a bit faster, because it does not have to allocate a new
temporary array.Whether this difference matters depends on the case.
In my own philosophy, every code that I write to be reusable, could at
some point be used in a situation where it is repeated a lot, and thus
has a performance impact. So for my taste, it does matter.This said, I understand it not having the greatest priority.
You can merge the result with default values like this:
[$foo, $bar, $foobar] = explode(':', 'foo:bar') + [23, 42, 1337];
var_dump($foo, $bar, $foobar);--
One could argue that:
[$foo, $bar, $foobar = 1337] = explode(':', 'foo:bar');
is more readable. I find it a small but nice addition
that doesn't clutter the language.
r//Björn
that doesn't clutter the language.
It actually does: now we have an expression-alike node that is lazy and
only evaluated when there's no default value. That's a lot of added
semantics for such an edge case feature.
Marco Pivetta
On Mon, Aug 14, 2017 at 11:35 AM, Björn Larsson bjorn.x.larsson@telia.com
wrote:
Den 2017-08-12 kl. 02:37, skrev Andreas Hennings:
This is true, I remember having done it in the past.
I still think it would be nice and feel natural to have the default
values directly built into the list construct.It would be a bit faster, because it does not have to allocate a new
temporary array.Whether this difference matters depends on the case.
In my own philosophy, every code that I write to be reusable, could at
some point be used in a situation where it is repeated a lot, and thus
has a performance impact. So for my taste, it does matter.This said, I understand it not having the greatest priority.
On Fri, Aug 11, 2017 at 7:46 PM, Andreas Treichel gmblar@gmail.com
wrote:You can merge the result with default values like this:
[$foo, $bar, $foobar] = explode(':', 'foo:bar') + [23, 42, 1337];
var_dump($foo, $bar, $foobar);--
One could argue that:
[$foo, $bar, $foobar = 1337] = explode(':', 'foo:bar');is more readable. I find it a small but nice addition
that doesn't clutter the language.r//Björn