PHP Multiple variable object properties - php

Question

I'm working with a third-party class, and I need to be able to run a section of code one of two ways, depending...
$reader->get()->first()->each(function($obj)
{
// Do stuff
}
OR
$reader->get()->each(function($obj)
{
// Do stuff
}
I've always been able to call properties variably with something like...
$a = 1;
$obj->{"$a"}
But unfortunately the below doesn't work...
if (some scenario)
{
$a = "get()->first()";
}
else
{
$a = "get()";
}
$reader->{"$a"}->each(function($obj)
My problem is i'm not sure how to phrase the question for google...I'm assuming there's a solution for the above problem.
Thanks in advance for any help!

Answer 1

You can only use ->{$variable} for the names of properties and methods of the class itself, you can't put PHP syntax like -> in there. What you can do is use function variables:
function get_all($reader) {
return $reader->get();
}
function get_first($reader) {
return $reader->get()->first();
}
$a = 'get_all'; // or $a = 'get_first';
$a($reader)->each(function($obj) {
// do stuff
});

Answer 2

Alternative to Barmar's answer, which imho is a bit clearer.
$it = function($obj) {
// do stuff
});
if (some_scenario) {
$reader->get()->first()->each($it);
} else {
$reader->get()->each($it);
}
One more solution:
if (some_scenario) {
$foo = $reader->get()->first();
} else {
$foo = $reader->get();
}
$foo->each(function($obj) {
// do stuff
});