LPM: Strict variable checking in classes?

[Wesley Sheldahl]

One solution is to use accessor methods to access all your class
attributes, and don't allow yourself to access them directly from outside
the class.  To help with this, name all the instance variables with a
leading underscore, so you have $_count.  To get its value, print
$this->count(), which looks something like

sub count { return $_count }

The method can do other validation, handle increments, and so forth too. 
Now calling a non-existent method should cause a speedy and traceable
error.  AUTOLOAD can make more interesting things happen.  Read the Conway
OOP book, it spends a fair amount of time on several different approaches
to this problem.

On 2001.03.28 22:58 David Hempy wrote:

> 
> However, the laid-back approach of hash lookups will happily let me print
> a 
> useless $this->{coutn} after incrementing $this->{count} a few thousand 
> times.  Tracking down typos like that can be a real pain.  (And a 
> shuddering C programmer now beams...)
> 
> Is this just the nature of the beast?  Are there other ways to handle 
> instance variables in a class?  I fully expect to find the answer ten 
> seconds after I send this message, so wish me luck.
> 
> -dave
> 
> 
> ps. I've ordered the OOP book that several in the group have 
> promoted...hope to have this program done before it gets here.
> 
> -- 
> David Hempy
> Internet Database Administrator
> Kentucky Educational Television - Distance Learning Division
> <hempy at ket.org> -- (859)258-7164 -- (800)333-9764
> 
> 
> 
-- 
Wes Sheldahl
wsheldahl at qx.net