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I want to write a function that does some dirty work logging a transaction, but the anonymous function scope does not seem to register the parent scope $db and $value variables. How can I pass the variables into the closure?
Ironically, the SO tag 'closures' does not describe the PHP version of it very accurately...?
class controller { function submit() { $db = new database(); $result = $db->execute_tx(function() { $db->insert_model_a($value_a); // ERROR: $db is non-object $db->insert_model_b($value_b); }); } } class database { function execute_tx($atomic_action) { try { $this->start(); $atomic_action(); $this->commit(); // etc.. } catch(...) { $this->rollback(); // etc.. } finally { // etc.. } } function insert_model_a() { ... } function insert_model_b() { ... } } 
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Yes, use a closure: functionName($someArgument, function() use(&$variable) { $variable = "something"; }); Note that in order for you to be able to modify $variable and retrieve the modified value outside of the scope of the anonymous function, it must be referenced in the closure using & . It's new!
As of PHP 7.1, these variables must not include superglobals, $this , or variables with the same name as a parameter.
To access the global variable within a function, use the GLOBAL keyword before the variable. However, these variables can be directly accessed or used outside the function without any keyword.
Accessing global variable inside function: The ways to access the global variable inside functions are: Using global keyword. Using array GLOBALS[var_name]: It stores all global variables in an array called $GLOBALS[var_name]. Var_name is the name of the variable.
Use the use keyword to bind variables into the function's scope.
function() use ($db) { Closures may also inherit variables from the parent scope. Any such variables must be declared in the function header [using
use].http://www.php.net/manual/en/functions.anonymous.php
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