I'm pretty sure this is a very basic question to all of you, but i'm new with php, and i don't really get it...
basically i've created a function in which i need to pass two parameters.
My functions is this:
function displayRoomDetails($customerRooms, $test)
{
foreach ($customerRooms as $room) {
$test.= $room->name;
};
}
it is a very basic function, but will do for this example.
Now, i'm creating templates to display several information, and i have 3 different layout where i need to display the same info but styled differently, so my approach was:
template1 .= '<span>';
if (!$customerRooms == "") {
displayRoomDetails($customerRooms,"template1");
};
template1 .= '</span>';
It should be pretty easy to understand, basically i'm calling the same functions in all the different templates passing as a parameter the template name and trying to append the results to the right template.
The problem i've got is this:
According to this example here ->
http://www.w3schools.com/php/showphp.asp?filename=demo_function3
i should be able to do this exactly like i did, but when i try, when i debug my function, $template doesn't take the passed value as i though it would, but it is still called $test and not $template1...
What am i doing wrong?
Thanks
Try these changes:
function displayRoomDetails($customerRooms, &$test)
And
$template1 .= '<span>';
if ($customerRooms != "") {
displayRoomDetails($customerRooms, $template1);
};
$template1 .= '</span>';
From what I understand you want to append some text to the template1 variable using the displayRoomDetailsFunction
Some things to fix:
template1 should be $template1
You should be passing the $template1 not the "template1" (i.e. the variable itself not its name).
If you want to modify this variable you need to either:
pass it as reference, which you can do by changing the function's declaration to: function displayRoomDetails($customerRooms, &$test)
return new string from function and assign it to the $template1 by adding return $test; just after your foreach block and changing the call to $template1 .= displayRoomDetails($customerRooms,$template1);
Additional note: if $customerRooms is an array, it'd be better to check if it's not empty using count() than !$customerRooms == "", see #andrew's comment for details
Related
I am trying to create a Blade directive that will set a class on my table row depending on what gets passed in. The problem is that when I call it, the value of the variable is not being passed in - the literal string that I have between the parenthesis is.
In my view:
#row($inspection->inspection_disposition)
In the directive:
Blade::directive('row', function($data)
{
var_dump($data);
.
.
.
}
What I see in the dump is:
string(37) "($inspection->inspection_disposition)"
Shouldn't I see the value of that variable? That's what I want. What am I missing here?
MORE INFO:
I need to use the value of that variable in the directive, like this:
if($data == "hello")
{
return something
}
elseif($data == "goodbye")
{
return something else
}
This is a simplified example, but hopefully it will help to illustrate that I need to compare the value of the variable inside the directive, then determine what to do. Perhaps I need to use eval() ?
Blade directive should return a string that php will interprete, like this:
Blade::directive('row', function($data)
{
return "<?php var_dump($data); ?>";
}
Here's the secret:
It's not pass by value or pass by reference it's kind of like pass by variable name.
So think of it this way:
When you call:
#row($data)
imagine that you are calling:
$row('$data') /* Don't actually do this */
Because that's how essentially laravel processes it. It's going to take the names of the variables you pass and insert them into the php code that you return to the view.
So like #RDev's answer, place the following (in the boot() function of app\Providers\AppServiceProvider.php):
Blade::directive('row', function($parameter)
{
return "<?php var_dump($parameter); ?>";
}
The $data variable will hold this literal value that you passed it "$data". And it will swap that into your php code like so:
<?php var_dump($data); ?>
And then that php code will get inserted into your view in place of the #row blade directive.
Here is my anonymous function:
$step = function() use ($text,$count,$new_text) {
$new_text .= $text[$count];
$count++;
I'm reading a long text value and scanning for bad characters. If the value of $text[$count] is ok, I want to add it to the new text variable and increase the count by calling $step(). Sure, I could just repeat the two lines over and over in my code, but using an anonymous function seemed so much simpler. The only problem is that it doesn't work. The variables aren't changing in the outer function.
What am I doing wrong. Alternatively, what's a different way to do this if there is one? There has to be a way to abstract a few lines of repeated code throughout a function.
You MUST pass by reference if want a modified version of variable after function is performed, like this:
<?php
$text = 'Some text';
$anon = function() use (&$text) {
$text .= ' and more...' ;
};
$anon();
print $text; // returns: Some text and more...
The use statement just inherit variables from the parent scope.
Ok, I'm looking into using create_function for what I need to do, and I don't see a way to define default parameter values with it. Is this possible? If so, what would be the best approach for inputting the params into the create_function function in php? Perhaps using addslashes?
Well, for example, I have a function like so:
function testing($param1 = 'blah', $param2 = array())
{
if($param1 == 'blah')
return $param1;
else
{
$notblah = '';
if (count($param2) >= 1)
{
foreach($param2 as $param)
$notblah .= $param;
return $notblah;
}
else
return 'empty';
}
}
Ok, so how would I use create_function to do the same thing, adding the parameters and their default values?
The thing is, the parameters are coming from a TEXT file, as well as the function itself.
So, wondering on the best approach for this using create_function and how exactly the string should be parsed.
Thanks :)
Considering a function created with create_function this way :
$func = create_function('$who', 'echo "Hello, $who!";');
You can call it like this :
$func('World');
And you'll get :
Hello, World!
Now, having a default value for a parameter, the code could look like this :
$func = create_function('$who="World"', 'echo "Hello, $who!";');
Note : I only added the default value for the parameter, in the first argument passed to create_function.
And, then, calling the new function :
$func();
I still get :
Hello, World!
i.e. the default value for the parameter has been used.
So, default values for parameters work with create_function just like they do for other functions : you just have to put the default value in the list of parameters.
After that, on how to create the string containing the parameters and their values... A couple of string concatenations, I suppose, without forgetting to escape what should be escaped.
Do you want to create an anonymous function? The create_function is used to create the anonymous functions. Otherwise you need to create function normally like:
function name($parms)
{
// your code here
}
If you want to use the create_function, here is the prototype:
$newfunc = create_function('$a,$b', 'return "ln($a) + ln($b) = " . log($a * $b);');
echo "New anonymous function: $newfunc\n";
echo $newfunc(2, M_E) . "\n";
// outputs
// New anonymous function: lambda_1
// ln(2) + ln(2.718281828459) = 1.6931471805599
I'm having the same problem, trying to pass an array to a created callback function... I think I'll create a temporary variable... It's ugly but I have better to do then torture myself with slashes, my code is already cryptic enough the way it is now.
So, to illustrate:
global $tmp_someArray;
$tmp_someArray = $someArray;
$myCallback = create_function(
'$arg1',
'
global $tmp_someArray;
// do stuff with $tmp_someArray and $arg1....
return($something);
'
);
Anyone has an idea if this is at all possible with PHP?
function foo($var) {
// the code here should output the value of the variable
// and the name the variable has when calling this function
}
$hello = "World";
foo($hello);
Would give me this output
varName = $hello
varValue = World
EDIT
Since most people here 'accuse' me of bad practices and global variables stuff i'm going to elaborate a little further on why we are looking for this behaviour.
the reason we are looking at this kind of behaviour is that we want to make assigning variables to our Views easier.
Most of the time we are doing this to assign variables to our view
$this->view->assign('products', $products);
$this->view->assign('members', $members);
While it would be easier and more readable to just be able to do the following and let the view be responsible to determining the variable name the assigned data gets in our views.
$this->view->assign($products);
$this->view->assign($members);
Short answer: impossible.
Long answer: you could dig through apd, bytekit, runkit, the Reflection API and debug_backtrace to see if any obscure combination would allow you to achieve this behavior.
However, the easiest way is to simply pass the variable name along with the actual variable, like you already do. It's short, it's easy to grasp, it's flexible when you need the variable to have a different name and it is way faster than any possible code that might be able to achieve the other desired behavior.
Keep it simple
removed irrelevant parts after OP edited the question
Regardless of my doubt that this is even possible, I think that forcing a programmer on how to name his variables is generally a bad idea. You will have to answer questions like
Why can't I name my variable $arrProducts instead of $products ?
You would also get into serious trouble if you want to put the return value of a function into the view. Imagine the following code in which (for whatever reason) the category needs to be lowercase:
$this->view->assign(strtolower($category));
This would not work with what you're planning.
My answer therefore: Stick to the 'verbose' way you're working, it is a lot easier to read and maintain.
If you can't live with that, you could still add a magic function to the view:
public function __set($name, $value) {
$this->assign($name, $value);
}
Then you can write
$this->view->product = $product;
I don't think there is any language where this is possible. That's simply not how variables work. There is a difference between a variable and the value it holds. Inside the function foo, you have the value, but the variable that held the value is not available. Instead, you have a new variable $var to hold that value.
Look at it like this: a variable is like a bucket with a name on it. The content (value) of the variable is what's inside the bucket. When you call a function, it comes with its own buckets (parameter names), and you pour the content of your bucket into those (well, the metaphor breaks down here because the value is copied and still available outside). Inside the function, there is no way to know about the bucket that used to hold the content.
What you're asking isn't possible. Even if it was, it would likely be considered bad practice as its the sort of thing that could easily get exploited.
If you're determined to achieve something like this, the closest you can get would be to pass the variable name as a string and reference it in the function from the $GLOBALS array.
eg
function this_aint_a_good_idea_really($var) {
print "Variable name: {$var}\n";
print "Variable contents: {$GLOBALS[$var]}\n";
}
$hello="World";
this_aint_a_good_idea_really('hello');
But as I say, that isn't really a good idea, nor is it very useful. (Frankly, almost any time you resort to using global variables, you're probably doing something wrong)
Its not impossible, you can find where a function was invoked from debug_backtrace() then tokenize a copy of the running script to extract the parameter expressions (what if the calling line is foo("hello $user, " . $indirect($user,5))?),
however whatever reason you have for trying to achieve this - its the wrong reason.
C.
Okay, time for some ugly hacks, but this is what I've got so far, I'll try to work on it a little later
<?php
class foo
{
//Public so we can test it later
public $bar;
function foo()
{
//Init the array
$this->bar = array();
}
function assign($__baz)
{
//Try to figure out the context
$context = debug_backtrace();
//assign the local array with the name and the value
//Alternately you can initialize the variable localy
//using $$__baz = $context[1]['object']->$__baz;
$this->bar[$__baz] = $context[1]['object']->$__baz;
}
}
//We need to have a calling context of a class in order for this to work
class a
{
function a()
{
}
function foobar()
{
$s = "testing";
$w = new foo();
//Reassign local variables to the class
foreach(get_defined_vars() as $name => $val)
{
$this->$name = $val;
}
//Assign the variable
$w->assign('s');
//test it
echo $w->bar['s'];
}
}
//Testrun
$a = new a();
$a->foobar();
impossible - the max. ammount of information you can get is what you see when dumping
debug_backtrace();
Maybe what you want to do is the other way around, a hackish solution like this works fine:
<?php
function assign($val)
{
global $$val;
echo $$val;
}
$hello = "Some value";
assign('hello');
Ouputs: Some value
What you wish to do, PHP does not intend for. There is no conventional way to accomplish this. In fact, only quite extravagant solutions are available. One that remains as close to PHP as I can think of is creating a new class.
You could call it NamedVariable, or something, and as its constructor it takes the variable name and the value. You'd initiate it as $products = new NamedVariable('products', $productData); then use it as $this->view->assign($products);. Of course, your declaration line is now quite long, you're involving yet another - and quite obscure - class into your code base, and now the assign method has to know about NamedVariable to extract both the variable name and value.
As most other members have answered, you are better off suffering through this slight lack of syntactic sugar. Mind you, another approach would be to create a script that recognizes instances of assign()'s and rewrites the source code. This would now involve some extra step before you ran your code, though, and for PHP that's silly. You might even configure your IDE to automatically populate the assign()'s. Whatever you choose, PHP natively intends no solution.
This solution uses the GLOBALS variable. To solve scope issues, the variable is passed by reference, and the value modified to be unique.
function get_var_name(&$var, $scope=FALSE) {
if($scope) $vals = $scope;
else $vals = $GLOBALS;
$old = $var;
$var = $new = 'unique'.rand().'value';
$vname = FALSE;
foreach ($vals as $key => $val) {
if($val === $new) $vname = $key;
}
$var = $old;
return $vname;
}
$testvar = "name";
echo get_var_name($testvar); // "testvar"
function testfunction() {
$var_in_function = "variable value";
return get_var_name($var_in_function, get_defined_vars());
}
echo testfunction(); // "var_in_function"
class testclass {
public $testproperty;
public function __constructor() {
$this->testproperty = "property value";
}
}
$testobj = new testclass();
echo get_var_name($testobj->testproperty, $testobj); // "testproperty"
The code below is just a sample of the format I have
isset($_GET['ids'])?$ids=$_GET['ids']:null;
isset($_POST['idc'])?$idc=$_POST['idc']:null;
function ShowCart()
{
$que = "SELECT
FROM
cart
LEFT OUTER JOIN ...
ON ...
LEFT OUTER JOIN... ON...
WHERE ";
$result = mysql_query($que);
while(){
if (isset($ids)) {
display something
for (){
if(){
} // end of if inside the for loop
}// end of for loop
}
elseif($idc && $ids=null) {
display something different
}
else{
display nothing has passed
}
}//end of while loop
}//end of showcart(); function
that's the formatting above I wonder why the if and elseif are not getting the isset() as the if and elseif argument.
I have debug the through the whole code and the print_r of GET and POST has values through the whole code.
print_r($_POST);
print_r($_GET);
Jona, if you'd ever bother to properly format your code, you'd see that the 'else' in question is WITHIN A FUNCTION, and you're defining $ids and $idc OUTSIDE THE FUNCTION. Remember, in PHP, global variables (except the super-globals, such as $_GET, $_POST, etc...) are not visible within functions unless you explicity define them as globals within the function.
Add global $idc, $idc; as the first line in the function definition and your if() will start working correctly.
Followup:
Your code is still hideously formatted, and very wonky. Take this:
isset($_GET['ids'])?$ids=$_GET['ids']:null;
You're using a trinary operator, but not assigning its results anywhere, and using the 'true' condition to do an assignment. This is an ugly hack. It should be written like this:
$ids = isset($_GET['ids']) ? $_GET['ids'] : null;
This way $ids will be set to null if there is no $_GET['ids']. Which brings up the fact that you're assigning a null instead of some other default value. If there really was no $_GET['ids'], then this:
$idx = $_GET['ids'];
would work identically, as PHP will automatically assign a null in situations where the right-hand-side doesn't exist. Of course, you still have to sanitize this value, since you're using it in an SQL query later on. Leaving it like this will just invite SQL injection attacks and all kinds of other abuses.
Beyond that, you're still creating $ids and $idc OUTSIDE of your ShowCart() function. As such, $ids and $idc within the function will be automatically be created with null values, since you've not declared them to be global. I think by now it's obvious you have no idea what this means, so try out this piece of code:
<?php
$var = 'Here I am!';
function showVar() {
echo "Within showVar(), var is set to: $var\n";
}
function workingShowVar() {
global $var;
echo "Within workingShowVar(), var is equal to: $var\n";
}
showVar();
workingShowVar();
If you copy/paste this code, run it, you'll see the following output:
Within showVar(), var is set to:
Within workingShowVar(), var is set to: Here I am!
Notice that both functions are identical, except for the global declaration. If you can figure out the difference, then you'll realize you need to re-write your ShowCart() function as follows:
function ShowCart() {
global $ids, $idc;
// rest of your code here
}
Well the code you've posted is sound, so it's probably a problem with the variables getting to that script in the first place. Are you sure those variables are defined in the GET string?
Dump out the contents of it to make sure:
print_r($_GET);
Try this:
$ids= isset($_GET['ids'])?intval($_GET['ids']):null;
$idc= isset($_GET['idc'])?intval($_GET['idc']):null;
if (isset($ids)) {
//display something
}
elseif(isset($idc)) {
//display something different
}
else
{
//display nothing has passed
}
I tested your script above,it works as expected.Maybe you should check whether the link is correct or not.