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Non-exception Error Handling Techniques

Non-exception Error Handling Techniques

Learn about non-exception-based error handling techniques like callbacks, PHP error messages, default values, and sum types.

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The following techniques are among the error handling techniques that are not based on exceptions:

  • Callbacks
  • PHP error messages
  • Default values
  • Sum types

Callbacks

A callback is a function that serves as an argument of a higher-order function. Callbacks mitigate failure when they’re used in place of exceptions. Consider the following snippet:

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<?php
function head(array $numbers)
{
  return $numbers[0];
}
echo head([1,2,3,4,5]);
?>

The head function shown above returns the first index of an integer-indexed array. The sample size for the function above is every collection with integer indexes. Suppose one intends to supply a string-indexed list to the head function. The result will likely be a notice similar to the one shown below:


PHP Notice: Undefined offset: 0 in php shell code on line 1

Notice: Undefined offset: 0 in php shell code on line 1

Typically, an exception is used to address the possibility of parsing a non-integer-indexed list, but the costly nature of exception-object creation and stack-trace generation warrants preemption. A ...