PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

158 Chapter 5 Reusing Code and Writing Functions
There is something very elegant and mathematical about recursive solutions. In most
cases, however, you are better off using an iterative solution.The code for such a solution
is also shown in Listing 5.5. Note that it is no longer (although this is not always the case
with iterative functions) and does exactly the same thing.The main difference is that the
recursive function makes copies of itself in memory and incurs the overhead of multiple
function calls.
You might choose to use a recursive solution when the code is much shorter and
more elegant than the iterative version, but it does not happen often in this application
domain.
Although recursion appears more elegant, programmers often forget to supply a termination
condition for the recursion.This means that the function will recur until the
server runs out of memory, or until the maximum execution time is exceeded, whichever
comes first.
Namespaces
In general, a namespace is an abstract container that holds a group of identifiers; in PHP
this means that namespaces can contain the functions, constants, and classes that you
define. There are several organizational advantages for creating namespaces for your custom
function and class definitions, including:
n All functions, classes, and constants within a namespace are automatically prefixed
with the namespace name.
n Unqualified class, function, and constant names are resolved at runtime, with the
first search taking place in the namespace before moving out to the global space.
n All functions, classes, and constants within a namespace are automatically prefixed
with the namespace name.
For more information and practical examples of namespaces in PHP, please see the PHP
Manual at http://www.php.net/language.namespaces
Further Reading
The use of include(), require(), function, and return are also explained in the
online manual.To find out more details about concepts such as recursion, pass by value
or reference, and scope that affect many languages, you can look at a general computer
science textbook, such as Dietel’s and Dietel’s C++ How to Program.
Next
Now that you are using include files, require files, and functions to make your code
more maintainable and reusable, the next chapter addresses object-oriented software and
the support offered in PHP. Using objects allows you to achieve goals similar to the concepts
presented in this chapter, but with even greater advantages for complex projects.