troels knak-nielsen wrote:
1) It covers all the use cases for a type-based system (You can use
`is_integer` as a contract, if you want that)
2) It's extensible in user-space, which means that it can be used to
convey much more accurate information, relevant to the application
needs.
3) It's focused on the interface of input-parameters, rather than their type.
This is my favorite alternative so far. There are just a few problems
with parsing as I see it.
- How do you know if it is a contract or the current object type hint?
- It doesn't allow a type to be forced (casted) to the correct type.
To address these items, I suggest the following changes.
Change the syntax of the contract to look like a function call (which is
essentially what we are doing):
<?php
function array_of_numeric($x)
{
if (!is_array($x)) {
return false;
}
foreach ($x as $val) {
if (!is_numeric($val)) {
return false;
}
}
return true;
}
function sum(array_of_numeric($a)) {
return array_sum($a);
}
This could even be extended to allow for more generic types by allowing
constant parameters for the contract:
<?php
function array_of($x, $type)
{
if (!is_array($x)) {
return false;
}
switch ($type) {
case 'int':
$check = 'is_int';
break;
case 'float':
$check = 'is_float';
break;
case 'numeric':
$check = 'is_numeric';
break;
case 'string':
$check = 'is_string';
break;
case 'bool':
$check = 'is_bool';
break;
default:
return false;
}
foreach ($x as $val) {
if (!$check($val)) {
return false;
}
}
return true;
}
function sum(array_of($a, 'numeric')) {
return array_sum($a);
}
To allow for casting, the contract function could take the value by
reference and cast it:
<?php
function array_of_float(&$x)
{
if (!is_array($x)) {
return false;
}
foreach ($x as $key => $val) {
if (!is_numeric($val)) {
return false;
}
$x[$key] = (float)$val;
}
return true;
}
function sum(array_of_float($a)) {
return array_sum($a);
}
--
Joshua Thompson
Mechanical Engineer/Software Developer
http://www.schmalls.com
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