Tuesday, February 20. 2007
 |
 |
 |
 |
Posted by Frank Kleine
in
Planet PHP Comments (4) Trackbacks (0) |
 |
 |
 |
 |
Wishlist pt1 extended: more type hints
Yesterday evening Stephan wrote about the object type hint. Coincidentally, while being in my favourite bar, I was talking with Timm Friebe, a colleague of mine, about the scalar type hint:
This type hint would allow passing integers, floats, strings and boolean values, but no objects, arrays, resources and null values (null would be allowed if you make it
Having this type hint would have some advantages: you may never pass objects or arrays into this function which will be converted to strings, this will throw an E_CATCHABLE. It also still adheres to the PHP way I believe, because it does not specify the concrete scalar type and lets you the choice about it. Splitting this much more into strings, integers and so on is oversized and would not fit into PHP. (That it would be possible has already been demonstrated by Derick.)
However I think it is not that necessary, but it rounds off the whole type hint story in PHP and would allow doing some stuff with arrays (now I'm going really mad
):
function bar(scalar $baz) { ... }This type hint would allow passing integers, floats, strings and boolean values, but no objects, arrays, resources and null values (null would be allowed if you make it
function bar(scalar $baz = null) similarly to how type hints work until now).Having this type hint would have some advantages: you may never pass objects or arrays into this function which will be converted to strings, this will throw an E_CATCHABLE. It also still adheres to the PHP way I believe, because it does not specify the concrete scalar type and lets you the choice about it. Splitting this much more into strings, integers and so on is oversized and would not fit into PHP. (That it would be possible has already been demonstrated by Derick.)
However I think it is not that necessary, but it rounds off the whole type hint story in PHP and would allow doing some stuff with arrays (now I'm going really mad
):
Arrays with type hints
This first would be an array consisting of scalar values, the second an array of MyClass instances.
This would be a hashmap which takes only instances of MyClass as values. It would be helpful to the IDE as well, because iterating over the array with
Now we can use it as type hints on functions and methods as well:
Something similar to this has already been suggested in php-internals, but turned down by one of the core developers. The proposal of Sebastian is nice, but from my point of view it doesn't fit into PHP because PHP developers are not used to such a notation (too much Java as well).
Yes, my proposal looks a bit like Generics. It would be enough to have this for arrays, there is no need to have generics for objects in PHP, as mostly arrays are used for such stuff in PHP.
But stop dreaming. My guess is that this will never be implemented in PHP, at least not in the official distribution.
$foo = array<scalar>();
$bar = array<MyClass>();This first would be an array consisting of scalar values, the second an array of MyClass instances.
$foo = array<scalar,MyClass>()This would be a hashmap which takes only instances of MyClass as values. It would be helpful to the IDE as well, because iterating over the array with
foreach ($foo as $myClass) { ... } the IDE would know that $myClass is an instance of MyClass and can offer code completion.Now we can use it as type hints on functions and methods as well:
function foo(array<scalar,MyClass> $bar) { ... }Something similar to this has already been suggested in php-internals, but turned down by one of the core developers. The proposal of Sebastian is nice, but from my point of view it doesn't fit into PHP because PHP developers are not used to such a notation (too much Java as well
).Yes, my proposal looks a bit like Generics. It would be enough to have this for arrays, there is no need to have generics for objects in PHP, as mostly arrays are used for such stuff in PHP.
But stop dreaming. My guess is that this will never be implemented in PHP, at least not in the official distribution.
Trackbacks
Trackback specific URI for this entry
No Trackbacks
Comments
Display comments as
(Linear | Threaded)
Type hint won't be a good extension to PHP unless It could be omitted or else it's going to the Java's direction with tons of pointless code.
I also understand why arrays with type hints where turned down. Don't make PHP a language wich can be easily
integrated with IDE. Make IDE smarter, make phpdocs more informative or even better, create free phpdoc parser library, port it to C and Java so every IDE would use the same parser
I also understand why arrays with type hints where turned down. Don't make PHP a language wich can be easily
integrated with IDE. Make IDE smarter, make phpdocs more informative or even better, create free phpdoc parser library, port it to C and Java so every IDE would use the same parser
Well, the additional type hints should of course behave like the existing type hints for classes which means they are completely optional.
And its not just about better IDE integration. It will have the advantage of cleaner code which needs less checks - and it can be easier understand by others looking at the code.
And its not just about better IDE integration. It will have the advantage of cleaner code which needs less checks - and it can be easier understand by others looking at the code.
Yep, in full agreement - a "scalar" type hint makes a heap of sense for PHP.
What makes no sense is its omission in PHP5. Why have array, object and class hinting but leave out the final part to the puzzle.
Personally I'm a big fan of strongly typed languages, but I can also understand the direction PHP has moved in. But surely something such a loose "scalar" hint would be a great middle ground.
What makes no sense is its omission in PHP5. Why have array, object and class hinting but leave out the final part to the puzzle.
Personally I'm a big fan of strongly typed languages, but I can also understand the direction PHP has moved in. But surely something such a loose "scalar" hint would be a great middle ground.
Calendar
|
December '08 | |||||
| Mon | Tue | Wed | Thu | Fri | Sat | Sun |
| 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| 8 | 9 | 10 | 11 | 12 | 13 | 14 |
| 15 | 16 | 17 | 18 | 19 | 20 | 21 |
| 22 | 23 | 24 | 25 | 26 | 27 | 28 |
| 29 | 30 | 31 | ||||
Categories
Quicksearch
Blogs we read...
Syndicate This Blog
Blog Administration
