Asked  7 Months ago    Answers:  5   Viewed   37 times

I'm using a third party storage system that only returns me stdClass objects no matter what I feed in for some obscure reason. So I'm curious to know if there is a way to cast/convert an stdClass object into a full fledged object of a given type.

For instance something along the lines of:

//$stdClass is an stdClass instance
$converted = (BusinessClass) $stdClass;

I am just casting the stdClass into an array and feed it to the BusinessClass constructor, but maybe there is a way to restore the initial class that I am not aware of.

Note: I am not interested in 'Change your storage system' type of answers since it is not the point of interest. Please consider it more an academic question on the language capacities.

Cheers

 Answers

32

See the manual on Type Juggling on possible casts.

The casts allowed are:

  • (int), (integer) - cast to integer
  • (bool), (boolean) - cast to boolean
  • (float), (double), (real) - cast to float
  • (string) - cast to string
  • (array) - cast to array
  • (object) - cast to object
  • (unset) - cast to NULL (PHP 5)

You would have to write a Mapper that does the casting from stdClass to another concrete class. Shouldn't be too hard to do.

Or, if you are in a hackish mood, you could adapt the following code:

function arrayToObject(array $array, $className) {
    return unserialize(sprintf(
        'O:%d:"%s"%s',
        strlen($className),
        $className,
        strstr(serialize($array), ':')
    ));
}

which pseudocasts an array to an object of a certain class. This works by first serializing the array and then changing the serialized data so that it represents a certain class. The result is unserialized to an instance of this class then. But like I said, it's hackish, so expect side-effects.

For object to object, the code would be

function objectToObject($instance, $className) {
    return unserialize(sprintf(
        'O:%d:"%s"%s',
        strlen($className),
        $className,
        strstr(strstr(serialize($instance), '"'), ':')
    ));
}
Wednesday, March 31, 2021
 
BetaRide
answered 7 Months ago
14

So,

echo $object->distlat;
echo $object->distlng;

doesn't work for you?

Saturday, May 29, 2021
 
BenOfTheNorth
answered 5 Months ago
33

The lazy one-liner method

You can do this in a one liner using the JSON methods if you're willing to lose a tiny bit of performance (though some have reported it being faster than iterating through the objects recursively - most likely because PHP is slow at calling functions). "But I already did this" you say. Not exactly - you used json_decode on the array, but you need to encode it with json_encode first.

Requirements

The json_encode and json_decode methods. These are automatically bundled in PHP 5.2.0 and up. If you use any older version there's also a PECL library (that said, in that case you should really update your PHP installation. Support for 5.1 stopped in 2006.)


Converting an array/stdClass -> stdClass

$stdClass = json_decode(json_encode($booking));

Converting an array/stdClass -> array

The manual specifies the second argument of json_decode as:

assoc
When TRUE, returned objects will be converted into associative arrays.

Hence the following line will convert your entire object into an array:

$array = json_decode(json_encode($booking), true);
Sunday, June 6, 2021
 
Farnabaz
answered 5 Months ago
55

A public class variable in Java is equivalent to a global variable in C and Objective-C. You would implement it as:

class1.h

extern NSString* MyGlobalPassword;

class1.m

NSString* MyGlobalPassword = nil;

Then, anyone that imports class1.h can read and write to MyGlobalPassword.

A slightly better approach would be make it accessible via a "class method".

class1.h:

@interface Class1 : UIViewController {
    UITextField *usernameField;
    UITextField *passwordField;
    UIButton *loginButton;    
}
+ (NSString*)password;
@end

class1.m:

static NSString* myStaticPassword = nil;

@implementation Class1
+ (NSString*)password {
    return myStaticPassword;
}

- (void)didClickLoginButton:(id)sender {
    [myStaticPassword release];
    myStaticPassword = [passwordField.text retain];
}

Other classes would then read the password through the password class method.

Class2.m :

-(void) someMethodUsingPassword {
     thePassword = [Class1 password]; // This is how to call a Class Method in Objective C
     NSLog(@"The password is: %@", thePassword); 
}
Monday, August 9, 2021
 
mgraph
answered 3 Months ago
33

It could crash. As can be seen in the source code of the runtime here, it really just swaps the isa pointer.

If you really want to swap the isa to an isa of a subclass with more ivars, you should use class_createInstance with nonzero extraBytes.

Sunday, September 19, 2021
 
user3284707
answered 1 Month ago
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