[RFC] [DISCUSSION] Improve null-coalescing operator (??) adding empty check (??:)

6 years ago by Lito — view source

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Related with Request #75833 https://bugs.php.net/bug.php?id=75833

From PHP 7 null-coalescing operator is a great option to avoid a
previous exists check with isset.

But I think that this comaparison can be improved adding a ternary
operator like ??: and check also empty values.

Example:

<?php

$foo = '';

// Current response with ternary operator

echo $foo ?: 'default'; // 'defaut'

// Current response with null-coalescing operator

echo $foo ?? 'default'; // ''

// Possible response with ternary null-coalescing operator

echo $foo ??: 'default'; // 'defaut'

// Same response with current PHP available code

echo (isset($foo) && $foo) ? $foo : 'default'; // 'default'

/** ------------------------------- **/

$foo = false;

// Current response with ternary operator

echo $foo ?: 'default'; // 'defaut'

// Current response with null-coalescing operator

echo $foo ?? 'default'; // false

// Possible response with ternary null-coalescing operator

echo $foo ??: 'default'; // 'defaut'

// Same response with current PHP available code

echo (isset($foo) && $foo) ? $foo : 'default'; // 'default'

/** ------------------------------- **/

$foo = null;

// Current response with ternary operator

echo $foo ?: 'default'; // 'defaut'

// Current response with null-coalescing operator

echo $foo ?? 'default'; // 'defaut'

// Possible response with ternary null-coalescing operator

echo $foo ??: 'default'; // 'defaut'

// Same response with current PHP available code

echo (isset($foo) && $foo) ? $foo : 'default'; // 'default'

/** ------------------------------- **/

unset($foo);

// Current response with ternary operator

echo $foo ?: 'default'; // PHP Notice: Undefined variable: foo

// Current response with null-coalescing operator

echo $foo ?? 'default'; // 'defaut'

// Possible response with ternary null-coalescing operator

echo $foo ??: 'default'; // 'defaut'

// Same response with current PHP available code

echo (isset($foo) && $foo) ? $foo : 'default'; // 'default'

What about?

Thanks!
Lito.

6 years ago by Marco Pivetta — view source

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This:

echo (isset($foo) && $foo) ? $foo : 'default';

Is equivalent to:

echo $foo ?: 'default';

Please don't endorse usage of undefined variables.

Related with Request #75833 https://bugs.php.net/bug.php?id=75833

From PHP 7 null-coalescing operator is a great option to avoid a previous
exists check with isset.

But I think that this comaparison can be improved adding a ternary
operator like ??: and check also empty values.

Example:

<?php

$foo = '';

// Current response with ternary operator

echo $foo ?: 'default'; // 'defaut'

// Current response with null-coalescing operator

echo $foo ?? 'default'; // ''

// Possible response with ternary null-coalescing operator

echo $foo ??: 'default'; // 'defaut'

// Same response with current PHP available code

echo (isset($foo) && $foo) ? $foo : 'default'; // 'default'

/** ------------------------------- **/

$foo = false;

// Current response with ternary operator

echo $foo ?: 'default'; // 'defaut'

// Current response with null-coalescing operator

echo $foo ?? 'default'; // false

// Possible response with ternary null-coalescing operator

echo $foo ??: 'default'; // 'defaut'

// Same response with current PHP available code

echo (isset($foo) && $foo) ? $foo : 'default'; // 'default'

/** ------------------------------- **/

$foo = null;

// Current response with ternary operator

echo $foo ?: 'default'; // 'defaut'

// Current response with null-coalescing operator

echo $foo ?? 'default'; // 'defaut'

// Possible response with ternary null-coalescing operator

echo $foo ??: 'default'; // 'defaut'

// Same response with current PHP available code

echo (isset($foo) && $foo) ? $foo : 'default'; // 'default'

/** ------------------------------- **/

unset($foo);

// Current response with ternary operator

echo $foo ?: 'default'; // PHP Notice: Undefined variable: foo

// Current response with null-coalescing operator

echo $foo ?? 'default'; // 'defaut'

// Possible response with ternary null-coalescing operator

echo $foo ??: 'default'; // 'defaut'

// Same response with current PHP available code

echo (isset($foo) && $foo) ? $foo : 'default'; // 'default'

What about?

Thanks!
Lito.

6 years ago by Lito — view source

unread

No $foo ?: 'default' , it's only equivalent to (isset($foo) && $foo) ?
$foo : 'default' if $foo exists.

Also PHP has added ?? as null-coalescing operator that works with
undefined variables/attributes/keys, my proposal is an improvement over
this one.

I don't want to endorse usage of undefined variables, can be used in a
large set of situations, like object attributes, array keys, etc...

Anyway thanks for your feedback.
Lito.

This:

echo (isset($foo) && $foo) ? $foo : 'default';

Is equivalent to:

echo $foo ?: 'default';

Please don't endorse usage of undefined variables.

On 17 Jan 2018 19:00, "Lito" <info@eordes.com
mailto:info@eordes.com> wrote:

Related with Request #75833 https://bugs.php.net/bug.php?id=75833
<https://bugs.php.net/bug.php?id=75833>

>From PHP 7 null-coalescing operator is a great option to avoid a
previous exists check with isset.

But I think that this comaparison can be improved adding a ternary
operator like ??: and check also empty values.

Example:

--------------------------------------

&lt;?php

$foo = '';

// Current response with ternary operator

echo $foo ?: 'default'; // 'defaut'

// Current response with null-coalescing operator

echo $foo ?? 'default'; // ''

// Possible response with ternary null-coalescing operator

echo $foo ??: 'default'; // 'defaut'

// Same response with current PHP available code

echo (isset($foo) && $foo) ? $foo : 'default'; // 'default'

/** ------------------------------- **/

$foo = false;

// Current response with ternary operator

echo $foo ?: 'default'; // 'defaut'

// Current response with null-coalescing operator

echo $foo ?? 'default'; // false

// Possible response with ternary null-coalescing operator

echo $foo ??: 'default'; // 'defaut'

// Same response with current PHP available code

echo (isset($foo) && $foo) ? $foo : 'default'; // 'default'

/** ------------------------------- **/

$foo = null;

// Current response with ternary operator

echo $foo ?: 'default'; // 'defaut'

// Current response with null-coalescing operator

echo $foo ?? 'default'; // 'defaut'

// Possible response with ternary null-coalescing operator

echo $foo ??: 'default'; // 'defaut'

// Same response with current PHP available code

echo (isset($foo) && $foo) ? $foo : 'default'; // 'default'

/** ------------------------------- **/

unset($foo);

// Current response with ternary operator

echo $foo ?: 'default'; // PHP Notice:  Undefined variable: foo

// Current response with null-coalescing operator

echo $foo ?? 'default'; // 'defaut'

// Possible response with ternary null-coalescing operator

echo $foo ??: 'default'; // 'defaut'

// Same response with current PHP available code

echo (isset($foo) && $foo) ? $foo : 'default'; // 'default'

--------------------------------------

What about?

Thanks!
Lito.

6 years ago by Nikita Popov — view source

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No $foo ?: 'default' , it's only equivalent to (isset($foo) && $foo) ?
$foo : 'default' if $foo exists.

Also PHP has added ?? as null-coalescing operator that works with
undefined variables/attributes/keys, my proposal is an improvement over
this one.

I don't want to endorse usage of undefined variables, can be used in a
large set of situations, like object attributes, array keys, etc...

What is the use case for the ??: operator?

Null-coalesce is very common, because undefined/null are typically used to
signal default values. Using any falsy value to indicate a default value
seems a lot more unusual and precarious to me, especially if you consider
PHP's specific semantics around falsiness (with the string "0" being falsy).

Nikita

This:

echo (isset($foo) && $foo) ? $foo : 'default';

Is equivalent to:

echo $foo ?: 'default';

Please don't endorse usage of undefined variables.

6 years ago by Andrey Andreev — view source

unread

Hi,

No $foo ?: 'default' , it's only equivalent to (isset($foo) && $foo) ? $foo
: 'default' if $foo exists.

Also PHP has added ?? as null-coalescing operator that works with undefined
variables/attributes/keys, my proposal is an improvement over this one.

I don't want to endorse usage of undefined variables, can be used in a large
set of situations, like object attributes, array keys, etc...

Anyway thanks for your feedback.
Lito.

There is a shorter version:

empty($foo) ? 'default' : $foo;

And I think that's quite convenient for the few use cases it has
(refer to Nikita's reply).

Cheers,
Andrey.

6 years ago by Lito — view source

unread

Hi,

No $foo ?: 'default' , it's only equivalent to (isset($foo) && $foo) ? $foo
: 'default' if $foo exists.

Also PHP has added ?? as null-coalescing operator that works with undefined
variables/attributes/keys, my proposal is an improvement over this one.

I don't want to endorse usage of undefined variables, can be used in a large
set of situations, like object attributes, array keys, etc...

Anyway thanks for your feedback.
Lito.

There is a shorter version:
 empty($foo) ? 'default' : $foo;
And I think that's quite convenient for the few use cases it has
(refer to Nikita's reply).

Cheers,
Andrey.

Yes, I think that:

$foo = $foo ??: 'default';

Is more clear and with less code than:

$foo = empty($foo) ? 'default' : $foo;

As ?? does.

Regards,
Lito.

6 years ago by Lito — view source

unread

This is a RFC karma request for my wiki account.

I want to create a RFC with my proposal: Improve null-coalescing
operator (??) adding empty check (??:)

First list message is: http://news.php.net/php.internals/101606

The main idea is simplify "empty" check on non existing keys or object
attributes. Same as "?:" but also checking undefined.

Current check:

$value = empty($user->thisOptionalAttributeCanBeEmptyOrNotExists) ?
'without value' : $user->thisOptionalAttributeCanBeEmptyOrNotExists;

New feature:

$value = $user->thisOptionalAttributeCanBeEmptyOrNotExists ??: 'without
value';

I think that could be very usefull on inline "exists" + "not empty"
checks with a more clear code.

It's possible?

Thanks,
Lito.

Hi,

No $foo ?: 'default' , it's only equivalent to (isset($foo) && $foo)
? $foo
: 'default' if $foo exists.

Also PHP has added ?? as null-coalescing operator that works with
undefined
variables/attributes/keys, my proposal is an improvement over this one.

I don't want to endorse usage of undefined variables, can be used in
a large
set of situations, like object attributes, array keys, etc...

Anyway thanks for your feedback.
Lito.

There is a shorter version:

empty($foo) ? 'default' : $foo;

And I think that's quite convenient for the few use cases it has
(refer to Nikita's reply).

Cheers,
Andrey.

Yes, I think that:

$foo = $foo ??: 'default';

Is more clear and with less code than:

$foo = empty($foo) ? 'default' : $foo;

As ?? does.

Regards,
Lito.