I can't seem to get any consistent info on this. Different sources appear to say different things and the venerable php.net itself (appears) not to explicitly state this - although, I must admit, I only had a quick look.
In cases where I am passing around 'heavy' objects, I need to pass by reference, but I don't want to keep typing:
function foo(TypeName& $obj)
if I can get away with simply
function foo(TypeName $obj)
So what does the standard say?
Here's what worked best for me when trying to script this (in case anyone else comes across this like I did):
$ pecl -d php_suffix=5.6 install <package>
$ pecl uninstall -r <package>
$ pecl -d php_suffix=7.0 install <package>
$ pecl uninstall -r <package>
$ pecl -d php_suffix=7.1 install <package>
$ pecl uninstall -r <package>
The -d php_suffix=<version> piece allows you to set config values at run time vs pre-setting them with pecl config-set. The uninstall -r bit does not actually uninstall it (from the docs):
vagrant@homestead:~$ pecl help uninstall
pecl uninstall [options] [channel/]<package> ...
Uninstalls one or more PEAR packages. More than one package may be
specified at once. Prefix with channel name to uninstall from a
channel not in your default channel (pecl.php.net)
Options:
...
-r, --register-only
do not remove files, only register the packages as not installed
...
The uninstall line is necessary otherwise installing it will remove any previously installed version, even if it was for a different PHP version (ex: Installing an extension for PHP 7.0 would remove the 5.6 version if the package was still registered as installed).
Just explaining my comment:
objects in foreach loops are always passed by reference
When you use a foreach loop for an array of objects the variable that you are using inside the loop is a pointer to that object so it works as a reference, any change on the object inside the loop is a change on the object outside. This is because:
objects are always passed by reference (@user3137702 quote)
Detailed and official explanation here.
When you copy and unset your variable:
$copyThing = $thing; unset($copyThing->property);
you are creating another pointer and unseting it, so the original value is a gone. As a matter of fact, since the foreach loop also uses a pointer the $things array is also affected.
check this ideone (notice the vardump [where the 'a' property is gone], as the output is the same as you got)
I do not know in which version it changed, if ever, as it seems like default object/pointer behavior
As a workaround (some ideas):
$x = clone($obj); (As long as the default copy constructor works for your objects)Both method calls will take about the same amount of time.
(It's good to be aware of performance consequences and you asked a reasonable question, but even so, the standard disclaimer1 about early optimization technically applies.)
1.
First, make program work.
Then, profile.
Finally, and maybe, optimize.
Donald Knuth said:
We should forget about small
efficiencies, say about 97% of the
time: premature optimization is the
root of all evil.
Never used any of those, but they look interesting..
Take a look at Gearman as well.. more overhead in systems like these but you get other cool stuff :) Guess it depends on your needs ..
Objects are passed (and assigned) by reference. No need to use address of operator.
Granted what I typed is an oversimplification but will suit your purposes. The documentation states:
For a more detailed explanation (explains the oversimplification as well as identifiers) check out this answer.