On 3/19/15 3:49 PM, Alex Bowers wrote:
This email is just to gauge the response for some syntactic sugar to be
added to PHP in regard to slicing an array.
My proposal is something similar to Pythons slice, in PHP this would look
like:
$slided = $array[1:4]
This will get the elements in positions 1,2,3,4. (1 through 4 inclusive),
ignoring the actual key of the array. The result for an array will be an
array with the keys preserved, in the same order. Any multi-dimensions are
also respected and returned within the array.
This is the same as using the array_slice method with the PRESERVE KEYS
fourth parameter passed through as true.
The result for a string is the string from the two positions indicated.
This is the same as using substr().
The benefits for this as I see it is:
1) No function overhead
2) More readable (opinionated)
3) Consistent with how we can select items from an array currently (using
index).
If the array is not long enough (for example, index 4 doesn't exist), then
a NOTICE is thrown, and the values returned are as much as possible; this
would be the same as calling $array[1:] which will get the items in
position 1 through to the end.
If the variable used contains a string, then this will get the values from
the string at those positions. The same way that $string[1] will get the
second character, $string[2:5] will get the third through to the sixth
character. This differs from array_slice which would throw a warning and
return null.
If the variable isn't either a string or an array (or convertible to
either); then a warning is thrown and null is returned, consistent with
current use ($int[0] will return null)
Arrays with associated keys cannot be selected by using the keys they have,
but instead should be selected by the position those keys hold.
For example, this is invalid:
$array['string':'end']. This should throw a fatal error.
The valid options are:
$array[from:to] - This gets the values from position 'from' to 'to'
inclusive
$array[from:] - This gets the values from the position 'from' to the end.
$array[:to] - This gets the values from the start to the position 'to'.
$array[:] will get all the items in the array ($same as doing $array)
A side addition, that may be considered is adding [-1] to get the last item
in the array. But that is not a main part of this RFC.
Thanks
Variations of this proposal have been discussed many times. I don't
recall what the pushback was but it's worth your time to check the
archives to see what the objections were and if you can address them,
and/or if the new engine in PHP 7 addresses them. (I suspect it
has/will ameliorate a lot of implementation-level issues with old
proposals.)
Personally I'd be in favor of such a syntax but I don't recall the
objections in the past beyond "meh, sugar".
--Larry Garfield
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