For now, I'm creating an instance like this:
function newInstance($clazz, $parameters = []) {
// Do other stuff before
if(!is_array($parameters)) {
$parameters = [$parameters];
}
// Do other stuff before
return (new ReflectionClass($clazz))->newInstanceArgs($parameters)
}
The problem is:
Using an array as a single parameter, interprets it as an array of parameters instead of a single one. I also thought about using "func_get_args" or adding a third optional parameter which defines if there's an array as parameter or the given array contains all parameters, but I don't like that.
For example:
newInstance('clazzname', ['my', 'array']);
// should interpreted as:
function __construct($firstString, $secondString$) {}
// and sometimes as (depends on the class):
function __construct($myArray) {}
Anyone have an idea?
I'd use variable-length arguments to handle this:
function newInstance($clazz, ...$parameters) {
// Do other stuff before
return (new ReflectionClass($clazz))->newInstanceArgs($parameters);
}
newInstance('clazzname', 'my', 'array');
// new clazzname('my', 'array');
newInstance('clazzname', ['my', 'array']);
// new clazzname(['my', 'array']);
Related
I have the following class method for creating a Twig environment object.
public function getView($filename,
array $customFunctions = null,
array $customFunctionArgs = null,
$debug = false) {
$loader = new \Twig_Loader_Filesystem('/App/Views/Templates/Main');
$twig = new \Twig_Environment($loader);
if (isset($customFunctions)) {
foreach ($customFunctions as $customFunction) {
$customFunction['name'] = new \Twig_SimpleFunction($customFunction['name'],
function ($customFunctionArgs) {
return $customFunction['method']($customFunctionArgs);
});
$twig->addFunction($customFunction['name']);
}
}
// Check debugging option
if ($debug == true && !$twig->isDebug()) {
$twig->enableDebug();
$twig->addExtension(new \Twig_Extension_Debug());
} elseif (!$debug && $twig->isDebug()) {
$twig->disableDebug();
}
$template = $twig->load($filename);
return $template;
}
Problem is, I don't understand how to pass values in order to make this work dynamically and keep all the objects in context and scope. For instance, here is how I'm trying to use it but can't pass the variables as a reference I guess?
$customFunctions = ['name' => 'customFunctionName',
'method' => $Class->method($arg)];
$customFunctionArgs = [$arg];
$template = $View->getView('template.html.twig', $customFunctions, $customFunctionArgs, true);
My environment is PHP 5.6 & Twig 1.35.0. I suppose this is not a Twig specific question per se, but more of how to use class objects within other classes/methods.
Félix Gagnon-Grenier's answer helped me find a solution to this problem. However, I feel the need to post an answer with all the missing pieces to the puzzle for anyone that needs a solution for this.
I believe it will make more sense if I start at the end and explain to the beginning. When creating your array, there are several things to consider.
Any class objects that are needed for the function have to be declared inside a use() with the closure.
Any arguments for the custom function must be declared as a function parameter for the closure. This will allow you to declare them later.
I ended up adding a sub-array with the arguments I needed for each custom function, that way I don't need to iterate over them separately.
$customFunctions = [
[
'name' => 'customFunction',
'method' => function($arg1, $arg2) use($Class) {
return $Class->customFunction($arg1, $arg2);
},
'arguments' =>
[
'arg1', 'arg2'
]
]
];
$template = $View->getView(
'template.html.twig',
true,
$customFunctions
);
echo $View->renderView($template);
Based on this code (reflective of question above), I had to make some notable modifications.
if (isset($customFunctions)) {
foreach ($customFunctions as $index => $customFunction) {
if (isset($customFunctions['arguments'])) {
$arguments = $customFunctions['arguments'];
} else {
$arguments = [];
}
$twigFunction = new \Twig_SimpleFunction(
$customFunction['name'],
function (...$arguments) use ($customFunction) {
return $customFunction['method'](...$arguments);
});
$twig->addFunction($twigFunction);
}
}
You can do this whatever way works for you, but there are important things to consider which I struggled with. Once again, your arguments MUST go into the function parameters. function (...$arguments) use ($customFunction). Your custom function will be passed in the use(). In order to actually pass the arguments in the closure, you must use ... to unpack them (as an array). This applies to PHP 5.6+. It allows the arguments to be dynamically expanded to the correct amount, otherwise you will get missing argument errors.
There are slight flaws in how you construct the custom functions data array and the loop that injects them into the template.
The custom functions should be a three dimensional array
$customFunctions = [
[ // notice the extra level, allowing you to access the name
'name' => 'customFunctionName',
'method' => function() { return 'wat'; }
// you need to pass a callable, not the result of a call
]
];
The scope is not inherited like you seem to think it is, you need to use() variables you intend to access. I personnally would not overwrite the 'name' value of the array, but that's uncanny paranoia of internal side effects, it seems to work in practice.
if (isset($customFunctions)) {
foreach ($customFunctions as $customFunction) {
$customFunction['name'] = new \Twig_SimpleFunction(
$customFunction['name'],
function () use ($customFunctionArgs, $customFunction) {
return $customFunction['method']($customFunctionArgs);
});
$twig->addFunction($customFunction['name']);
}
}
You might need to add looping over $args so that the correct args are sent to the correct function (send $args[0] to $customFunctions[0] etc.).
Note that this prevents you from sending a parameter into your custom function unless you add it in the loop:
function ($templateArg) use ($customFunctionArgs, $customFunction) {
return $customFunction['method']($customFunctionArgs, $templateArg);
}
Here is a gist with tests if you're interested.
I'm aware that you can have PHP functions with optional arguments like so:
function do_something($argument = null)
{
// argument not provided
if ($argument === null)
........
}
Consider the case that null/false and other values are all valid arguments to my function. How can I determine whether an argument was provided or not?
do_something(null); // argument provided
do_something(false); // argument provided
do_something(0); // argument provided
do_something("test"); // argument provided
do_something(new stdClass()); // argument provided
do_something(); // nothing provided
How can I detect the last case? I have thought about using func_num_args which would work in most cases but it doesn't work if I have several optional arguments.
Is there anything that solves this problem?
func_num_args() should work exactly as you want it to, because you might be assuming something that's actually not the case: You can't have optional arguments left out if they are in the middle of your arguments list.
So let's look at this function:
function test1 ($param1 = null, $param2 = null) {
return func_num_args();
}
If I call that with different parameter combinations I get the following results:
test1() => 0
test1(true) => 1
test1(true, true) => 2
There is just no way to call the function in a way where $param2 would be set while $param1 isn't. So you can map every possible output of func_num_args() to exactly one parameter configuration.
In the example above you can rely on the fact that
if the return value is 1, $param2 definitely hasn't been set, while $param1 has been.
For 0 it's 100% sure that neither one has been given.
And, of course, if it's 2 both are there.
What you actually would need are named parameters, as many other languages have them. PHP doesn't at the moment. NikiC actually wrote an RFC that suggests the addition of named parameters to PHP, but I think that's still way off in the future. You can check that out here: https://wiki.php.net/rfc/named_params
As these are not yet available, here are a few workarounds you can try:
Workaround 1
If you really need to be able to have all the parameters optional, try a parameter array:
function test1 (array $opts) {
if (!isset($opts['opt1'])) { $opts['opt1'] = 'default1'; }
if (!isset($opts['opt2'])) { $opts['opt2'] = 'default2'; }
}
Then you can call it like this:
test1(array('opt2' => true))
It would set the first parameter to "default1" while keeping the second. And there are definitely better and more elegant ways to do this (e.g. using an object instead), but the general idea is the same.
Workaround 2
You could also go with alias functions:
function test ($param1, $patam2) { ... ]
function testNoParam1 ($param2) {
test("default1", $param2);
}
That at least makes it very easy to read, but of course you need to pick the right function depending on the parameters you have.
Workaround 3
By adding a lot of additional code you could get really fancy and use a FactoryObject:
class FunctionExecutor {
private $param1 = "default1";
private $param2 = "default2";
public function param1($val) {
$this->param1 = $val;
return $this;
}
public function param2($val) {
$this->param2 = $val;
return $this;
}
public function execute() {
return yourFunction($this->param1, $this->param2);
}
}
This could be used like this:
$doSomething = new FunctionExecutor();
$returnValue = $doSomething->param2(42)->execute();
In this approach it would probably be a better idea to actually put your function into the object instead of defining it globally. Anyway...this is definitely a possibility, but not the most practical one. Just wanted to add it, because it has some benefits.
perhaps this will help: http://www.php.net//manual/en/function.func-get-args.php
$args = func_get_args();
if(!isset($arg[0])) {
echo 'no argument';
}
or
isset(func_get_arg(0));
Passing "null", "0", or "false" means that you allocate memory to store a variable, regardless it's scope, type, or size. Then it is used as a parameter to a function.
In PHP you cannot override functions by arguments, but you can access them by calling the "func_get_args()", and this is the only way to handle different numbers / types of arguments passed to a function:
function do_something() {
$args = func_get_args();
//do_something(stdClass, 1)
if($args[0] instanceof stdClass && is_numeric($args[1])) {
//handle
//return
//do_something(1, "string")
} else if(is_numeric($args[0]) && is_string($args[1])) {
//handle
//return
}
throw new Exception('invalid arguments');
}
do_something(new StdClass(), 100); //ok
do_something(100, "hell world") // ok
do_someting(); //throws Exception('invalid arguments');
In PHP 7, you can do:
function action(...$args) {
if (count($args) === 0) {
return action_default();
}
$var1 = array_shift($args);
$var2 = array_shift($args);
$var3 = array_shift($args);
// etc.
}
I'm using reflection to dynamically call methods.
$object = new $class;
$reflector = new ReflectionMethod($class, $method);
$reflector->invokeArgs($object, $arguments);
The $arguments array looks like:
Array
(
[fooparam] => false
[id] => 238133
)
The method called could be:
class MyClass
{
public function myMethod ($id, $fooParam)
{
// Whatever
}
}
The problem is that everything comes from frontend designers, depending on data-* attributes, href... so $arguments array has arbitrary sorting.
How can I sort this array to match method parameters?
O maybe, is there a better solution? Named parameters?
Use ReflectionMethod::getParameters() to get a list of arguments and filter map them to their corresponding position, e.g.:
$sorted_args = array_map(function($param) use($arguments) {
$name = $param->getName();
if (!isset($arguments[$name]) && !$param->isOptional())
throw new BadMethodCallException("Argument '{$name}' is mandatory");
return isset($arguments[$name]) ? $arguments[$name] : $param->getDefaultValue();
}, $reflector->getParameters());
You could also use a simple foreach loop, it's up to you.
Then invoke the method with $sorted_args instead:
$reflector->invokeArgs($object, $sorted_args);
I know that it is possible to call a function with a variable number of parameters with call_user_func_array() found here -> http://php.net/manual/en/function.call-user-func-array.php . What I want to do is nearly identical, but instead of a function, I want to call a PHP class with a variable number of parameters in it's constructor.
It would work something like the below, but I won't know the number of parameters, so I won't know how to instantiate the class.
<?php
//The class name will be pulled dynamically from another source
$myClass = '\Some\Dynamically\Generated\Class';
//The parameters will also be pulled from another source, for simplicity I
//have used two parameters. There could be 0, 1, 2, N, ... parameters
$myParameters = array ('dynamicparam1', 'dynamicparam2');
//The instantiated class needs to be called with 0, 1, 2, N, ... parameters
//not just two parameters.
$myClassInstance = new $myClass($myParameters[0], $myParameters[1]);
You can do the following using ReflectionClass
$myClass = '\Some\Dynamically\Generated\a';
$myParameters = array ('dynamicparam1', 'dynamicparam2');
$reflection = new \ReflectionClass($myClass);
$myClassInstance = $reflection->newInstanceArgs($myParameters);
PHP manual: http://www.php.net/manual/en/reflectionclass.newinstanceargs.php
Edit:
In php 5.6 you can achieve this with Argument unpacking.
$myClass = '\Some\Dynamically\Generated\a';
$myParameters = ['dynamicparam1', 'dynamicparam2'];
$myClassInstance = new $myClass(...$myParameters);
I implement this approach a lot when function args are > 2, rather then end up with an Christmas list of arguments which must be in a specific order, I simply pass in an associative array. By passing in an associative array, I can check for necessary and optional args and handle missing values as needed. Something like:
class MyClass
{
protected $requiredArg1;
protected $optionalArg1;
public function __construct(array $options = array())
{
// Check for a necessary arg
if (!isset($options['requiredArg1'])) {
throw new Exception('Missing requiredArg1');
}
// Now I can just localize
$requiredArg1 = $options['requiredArg1'];
$optionalArg1 = (isset($options['optionalArg1'])) ? $options['optionalArg1'] : null;
// Now that you have localized args, do what you want
$this->requiredArg1 = $requiredArg1;
$this->optionalArg1 = $optionalArg1;
}
}
// Example call
$class = 'MyClass';
$array = array('requiredArg1' => 'Foo!', 'optionalArg1' => 'Bar!');
$instance = new $class($array);
var_dump($instance->getRequiredArg1());
var_dump($instance->getOptionalArg1());
I highly recommend using an associative array, however it is possible to use a 0-index array. You will have to be extremely careful when constructing the array and account for indices that have meaning, otherwise you will pass in an array with offset args and wreck havoc with your function.
You can do that using func_get_args().
class my_class {
function __construct( $first = NULL ) {
$params = func_get_args();
if( is_array( $first ) )
$params = $first;
// the $params array will contain the
// arguments passed to the child function
foreach( $params as $p )
echo "Param: $p\n";
}
}
function my_function() {
$instance = new my_class( func_get_args() );
}
echo "you can still create my_class instances like normal:";
$instance = new my_class( "one", "two", "three" );
echo "\n\n\n";
echo "but also through my_function:";
my_function( "one", "two", "three" );
Basically, you simply pass the result of func_get_args to the constructor of your class, and let it decide whether it is being called with an array of arguments from that function, or whether it is being called normally.
This code outputs
you can still create my_class instances like normal:
Param: one
Param: two
Param: three
but also through my_function:
Param: one
Param: two
Param: three
Hope that helps.
I've found here
Is there a call_user_func() equivalent to create a new class instance?
the example:
function createInstance($className, array $arguments = array())
{
if(class_exists($className)) {
return call_user_func_array(array(
new ReflectionClass($className), 'newInstance'),
$arguments);
}
return false;
}
But can somebody tell me if there is an example for classes with protected constructors?
I have a function which takes in about 10 arguments, in which most of them are optional. I was wondering if I could implement it in such a way that the user of the function does not need to bother with the order of the parameters.
For example:
public function foo($arg1, $arg2, $arg3='',$arg4='', $arg5='', $arg6='', $arg7=''){}
Now, when I use this function I can simply
$this->foo($arg1val, $arg2val, $arg6val);
Is there a way in php to do so?
Here is how I implemented this:
I've listed the parameters accepted by the function in the API, so the user can pass the parameters in any order in an array with key=>value pairs.
For example:
public function argumentsFilter($origParams, $newParams){
$tmpArr = array();
foreach ($origParams as $origKey){
foreach($newParams as $newKey => $newVal){
if($newKey == $origKey){
$tmpArr[$origKey] = $newVal;
}
}
if(empty($tmpArr[$origKey])){
$tmpArr[$origKey] = '';
}
}
return $tmpArr;
}
public function foo($arg1, $arg2, $arg=array()){
$validArgList = array('arg3', 'arg4', 'arg5', 'arg6', 'arg7');
$correctedArgList = $this->argumentsFilter($validArgList, $arg);
}
Is there a more elegant way to do this?
10 parameters for a function is clearly too much. Pass arrays instead:
function foo(array $params) {
$defaults = array('foo' => true, 'bar' => false, ...);
$params = array_intersect_key($params, $defaults) + $defaults;
// work with $params['foo']
// maybe extract($params)
}
This example shows a function that accepts an arbitrary number of "named parameter" in any order, filters invalid values and establishes defaults values.
It is not possible, since php doesn't support named arguments.
You have 2 choices: to use array or to redesign your function so it has fewer parameters (the latter is preferred).
There are many ways to do that, but I recommend this method:
function doSomething($required, /*optional*/ $arguments = array()) {
$arguments = array_merge(array(
// set defaults
"argument" => "default value",
), $arguments);
var_dump($arguments);
}
It is very clean and easy to understand.