finally

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A finally block may also be specified after or instead of catch blocks. Code within the finally block will always be executed after the try and catch blocks, even if a return or yield statement is encountered, or if a Throwable error is not caught or is rethrown. It will be executed prior to resuming the normal execution flow. The only exception to this rule is when the script is terminated abruptly, such as by a call to exit() or by a fatal error (for example when the maximum execution time is exceeded).

Example #1 Throwable error handling with a finally block

<?php
function inverse($x) {
    return 1/$x;
}

try {
    echo inverse(5) . "\n";
} catch (\DivisionByZeroError $e) {
    echo 'Caught error: ',  $e->getMessage(), "\n";
} finally {
    echo "First finally.\n";
}

try {
    echo inverse(0) . "\n";
} catch (\DivisionByZeroError $e) {
    echo 'Caught error: ',  $e->getMessage(), "\n";
} finally {
    echo "Second finally.\n";
}

// Continue execution
echo "Hello World\n";

Output of the above example in PHP 8:

0.2
First finally.
Caught error: Division by zero
Second finally.
Hello World

When the call stack is unwound after a Throwable error has been thrown, all finally blocks it encounters along the way will be executed. In other words, nested finally blocks are executed even if the Throwable error is not caught by an adjacent catch block.

Example #2 All finally block will be executed

<?php
try {
    try {
        throw new Exception();
    } finally {
        echo "Inner finally\n";
    }
} catch (Exception $e) {
} finally {
    echo "Outer finally\n";
}

The above example will output:

Inner finally
Outer finally

Interaction between a `finally` block and a `return` statement

One notable interaction is between the finally block and a return statement. If a return statement is encountered inside either the try or the catch blocks, the finally block will still be executed. Moreover, the return statement is evaluated when encountered, but the result will be returned after the finally block is executed. Additionally, if the finally block also contains a return statement, the value from the finally block is returned.

Example #3 Interaction between return in finally block and a previous return

<?php
function testReturnTry() {
    try {
        echo 'Within try', "\n";
        return 'try';
    } finally {
        echo 'Within finally', "\n";
        return 'finally';
    }
}

function testReturnCatch() {
    try {
        throw new Exception('foo');
    } catch (Exception $e) {
        echo 'Within catch', "\n";
        return 'catch';
    } finally {
        echo 'Within finally', "\n";
        return 'finally';
    }
}

echo testReturnTry(), "\n";
echo testReturnCatch(), "\n";

The above example will output:

Within try
Within finally
finally
Within catch
Within finally
finally

Example #4 Interaction between the finally block and return

<?php
function testReturnTry() {
    try {
        return 'try';
    } finally {
        echo 'finally ';
    }
}

function testReturnCatch() {
    try {
        throw new Exception('foo');
    } catch (Exception $e) {
        return 'catch';
    } finally {
        echo 'finally ';
    }
}

echo testReturnTry(), "\n";
echo testReturnCatch(), "\n";

The above example will output:

finally try
finally catch

Interaction between a `finally` block and an exception thrown in a `try` block

If both the try block and the finally block throw an exception, the exception thrown from the finally block is the one that is propagated, and the exception thrown from the try block will be used as its previous exception.

Example #5 Exception in try and in finally

<?php

try {
    try {
        throw new Exception(message: 'Third', previous: new Exception('Fourth'));
    } finally {
        throw new Exception(message: 'First', previous: new Exception('Second'));
    }
} catch (Exception $e) {
    var_dump(
        $e->getMessage(),
        $e->getPrevious()->getMessage(),
        $e->getPrevious()->getPrevious()->getMessage(),
        $e->getPrevious()->getPrevious()->getPrevious()->getMessage(),
    );
}

The above example will output:

string(5) "First"
string(6) "Second"
string(5) "Third"
string(6) "Fourth"

Behaviour of a `finally` block in a Generator

If during the traversal of a generator a Throwable error is thrown, the finally within the generator will be executed, as it is the previous element of the call stack.

Example #6 finally block being run when an Exception has been thrown

<?php
function generate()
{
    try {
        yield 1;
        yield 2;
    } catch(\Exception $e) {
        echo 'catch';
    } finally {
        echo "finally\n";
    }
}

try {
    foreach (generate() as $i) {
        echo $i, "\n";
        throw new Exception();
    }
} catch(Exception $e) {
    echo 'outer catch';
}

The above example will output something similar to:

1
finally
outer catch

It is possible to yield within a finally block but if a Throwable error occurs and is not caught within the foreach a Cannot yield from finally in a force-closed generator Error is thrown.

Example #7 Error when yielding in finally block when an Exception has been thrown

<?php
function generate()
{
    try {
        yield 1;
        yield 2;
    } catch(\Exception $e) {
        echo 'catch';
    } finally {
        echo "finally\n";
        yield 3;
    }
}

try {
    foreach (generate() as $i) {
        echo $i, "\n";
        throw new Exception();
    }
} catch(Exception $e) {
    echo 'outer catch';
}

The above example will output something similar to:

1
finally

Fatal error: Uncaught Exception in /in/GbFmu:19
Stack trace:
#0 {main}

Next Error: Cannot yield from finally in a force-closed generator in /in/GbFmu:12
Stack trace:
#0 /in/GbFmu(19): generate()
#1 {main}
  thrown in /in/GbFmu on line 12

Interaction between a `finally` block and a call to exit()

When exit() is called within a try or a catch block all finally blocks are skipped.

Example #8 Interaction between finally block and exit() called in try block

<?php
try {
    echo 'quit';
    exit(0);
} finally {
    echo 'finally';
}

The above example will output:

quit

Example #9 Interaction between finally block and exit() called in catch block

<?php
try {
    throw new Exception('foo');
} catch (Exception $e) {
    echo 'catch';
    exit(0);
} finally {
    echo 'finally ';
}

The above example will output:

catch

Example #10 All finally blocks are skipped when exit() is called

<?php
try {
    try {
        echo 'quit';
        exit(0);
    } finally {
        echo 'inner finally ';
    }
} finally {
    echo 'outer finally';
}

The above example will output:

quit

When exit() is called within a finally block, all other outer finally blocks are skipped.

Example #11 Skipping outer finally block by calling exit()

<?php
try {
    try {
        echo 'try', "\n";
    } finally {
        echo 'inner finally ';
        exit(0);
    }
} finally {
    echo 'outer finally';
}

The above example will output:

try
inner finally

Edge case of calling exit() in a `foreach` over a generator

This one edge case behaviour is highly dependent on which version of PHP the code is executed.

<?php
function generate()
{
    try {
        yield 1;
        yield 2;
    } catch(\Exception $e) {
        echo 'catch';
    } finally {
        echo "inner finally\n";
    }
}

try {
    foreach (generate() as $i) {
        echo $i, "\n";
        exit(0);
    }
} finally {
    echo "outer finally\n";
}

Output of the above example prior to PHP 7.1.14, in PHP 7.2.0 and 7.2.1, and as of PHP 8.0.0

1
inner finally

Output of the above example as of PHP 7.1.14 and 7.2.2, and prior to PHP 8.0.0

finally

Interaction between a finally block and a return statement

Interaction between a finally block and an exception thrown in a try block

Behaviour of a finally block in a Generator

Interaction between a finally block and a call to exit()

Edge case of calling exit() in a foreach over a generator

Interaction between a `finally` block and a `return` statement

Interaction between a `finally` block and an exception thrown in a `try` block

Behaviour of a `finally` block in a Generator

Interaction between a `finally` block and a call to exit()

Edge case of calling exit() in a `foreach` over a generator