Re: Singleton Pattern
"Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> wrote in message
news:4569b188$2$631$bed64819@news.gradwell.net...
Karl Uppiano wrote:
I tend to agree. The question should not be "is the design pattern good
or
bad?" but rather, "does the solution require this design pattern?". A
good
design should attempt to choose a "good one" from the entire catalog of
design patterns.
You may not have meant that exactly how it sounded, but if you do then I
disagree profoundly. A good design is created on its own merits, /not/ by
scanning some menu of available patterns.
A good design is created on its own merits, but IME, a large application is
usually built up from a judicious selection of standard components and
design patterns: For loops, while loops, try/catch blocks, if/else blocks,
switch statements, goto's, functional decomposition, object orientation,
threads, critical sections, mutexes, semaphores, stacks, queues, arrays,
lists, vectors, hash maps, singletons, resource adapters, enterprise service
busses, and so on, every one a design pattern of some sort.
The actual design is application-specific of course, and its quality depends
on the knowledge, ingenuity and creativity of the designer. However, in a
modular, object-oriented world, re-use is encouraged. Therefore, I usually
*do* scan some menu, in my mind, of available modules and design patterns,
not always consciously of course -- starting with the JDK API or C++ object
libraries, Google, -- looking for parts, to see if someone already invented
what I need. That's the "research" part of R&D. In many cases, I will extend
or modify what's available. If nothing is available, then I will create my
own module from scratch as a last resort. Of course, the
application-specific "glue" logic is usually not available off-the-shelf.
My particular coding style comes from the electronics industry, where I
started my career. In electronics, everything is modular: Resistors,
capacitors, inductors, transistors, integrated circuits... Sure, you could
make your own components from scratch, but unless you're in that line of
work, it is extremely time-consuming and fraught with difficulty. So,
vendors build solutions from a menu of available parts and design patterns -
e.g., most transistor audio amplifiers are based on the same tried and true
design pattern, modified to meet specific requirements. But from these
standard components and design patterns, I can build a cell phone, a
wireless router, a television, microwave oven...