Kelly Cookson wrote:
A nice feature of running PHP as an interpreted language is the flexibility in variable typing. Variable type in PHP depends on context. You don't get that when you compile a program. Compiled programs require that you define variable types in advance and they can't change.
I'm staying out of this from a pure "Why use PHP?" standpoint, because
everybody knows my opinion. But this is an excellent observation and
one which really touches the core of my beliefs in programming.
Dynamic typing is the nuclear medicine of programming. In very specific
situations under rigorously controlled conditions it can do a couple of
things that no other technique can do. It is, however, extremely
dangerous and should be used only by highly trained professionals.
Unfortunately, the folks who most want to use it are often the ones
least qualified. And that's when you get into incredible pain and
suffering. In Java, I know that a field of type Customer contains a
Customer object. And even in RPG, I know that a 6.0 field is not going
to contain an email address. In dynamically typed languages, all bets
are off. And when you combine that with ADGA (Agile Development Gone
Awry), you end up with code where it's nearly impossible to tell what is
in a variable at any given time.
Careful, careful attention paid to variable naming and strict coding
standards can ameliorate some or even most of the problems, but very few
shops have such standards, and RPG shops in particular tend to have
nothing in place for their PHP development. And the time it bites you
is when you find yourself with an unexpected error in a not-particularly
well commented program where you're not even sure what's supposed to be
in the variable that's causing the error. Add to that the fact that
most scripting languages have very little in the way of solid impact
analysis and that's why they fare much better in prototyping and proof
of concept than in production development.
Dynamic typing makes it easy to throw together stuff quickly, but it
doesn't really get aroudn the maxim that you can have something done
fast or well, but not both. That's why static typing is 60% of
programming today and gaining share.
Joe
midrange.com
