[KLUG Programming] PHP arrays vs. structures

[Adam Tauno WIlliams]

> Yes, I was wondering if you were working with XML-RPC calls.
> I do have a single question below
> > > > This solves my problems 
> > > A common PHP phrase
> > > > since the structures I have to deal with never
> > > > use numeric keys, so if the first key is 0 then it is an array,
> > > > otherwise it must be a structure (keys are strings).  So I'm just lucky
> > > > (for once!) in this case.
> > > It's implicit, which means that unless the keys are explicitly set as
> > > strings, you can refer to them numerically.  That tidbit can be
> > > extremely helpful (because so much code doesn't explicitly set the
> > > key).  In your case the check code you were looking for is not even
> > > necessary.
> > But other languages (C, etc...) as well as documents (XML, etc...) do
> > clearly distinguish between an array and a structure.  Using the numeric
> > key = array hack I've constructed...
> >     function wrap($value) {
> >       $this->traceMessage('@OGoDocument:wrap');
> >       switch(gettype($value)) {
> >         case 'boolean':
> >           $this->traceMessage('@OGoDocument:wrap.boolean');
> >           $value = new XML_RPC_value($value, 'boolean');
> >          break;
> >         case 'integer':
> >           $this->traceMessage('@OGoDocument:wrap.integer');
> >           $value = new XML_RPC_value($value, 'int');
> >          break;
> >         case 'double':
> >           $this->traceMessage('@OGoDocument:wrap.double');
> >           $value = new XML_RPC_value($value, 'double');
> >          break;
> >         case 'string':
> >           $this->traceMessage('@OGoDocument:wrap.string');
> >           $value = new XML_RPC_value($value, 'string');
> >          break;
> >         case 'array':
> >           $this->traceMessage('@OGoDocument:wrap.array');
> >           $a = array();
> >           reset($value);
> >           if (key($value) == '0') {
> 
> Isn't this a string comparison as you have 0 in single quotes?  If
> you're looking for integers, why not drop the quotes or consider using
> ===?

It is a good question.  Documentation did not make it clear if key(...)
returns a type:mixed or a type:string.  Internally I think how PHP4
handles types is a bit loosey-goosey; nice for somethings but
jaw-grinding for others.  The examples (the ones I glanced at anyway)
seemed inconsistent among themselves.

http://us2.php.net/key says  key(....) returns mixed, so you're probably
correct, that the ticks/quotes are inappropriate.

> I don't know for sure that it will ever cause problems the way you're
> doing it, just a note on the type of comparison it will do.  I'm always
> leery of comparing anything to zero because it reminds me of how I've
> seem people look for results of functions (because return false can
> evaluate to zero).  If a function returns zero it is usually not the
> same as returning false.

Correct, I'm relying on foreach(...) to exhibit sane behaviour so that I
don't walk of the end of the array (which PHP permits), at which point
I'd assume key(...) would return 0, or false ????  I've never had any
problem with foreach(...)

> >             //array
> >             $this->traceMessage('@OGoDocument:wrap.array.array');
> >             $a_type = 'array';
> >             foreach ($value as $v)
> >                array_push($a, $this->wrap($v));
> >            } else {
> >                //struct
> >                $this->traceMessage('@OGoDocument:wrap.struct'); 
> >                $a_type = 'struct';
> >                foreach ($value as $k => $v)
> >                  $a[$k] = $this->wrap($v);
> >              }
> >           $value = new XML_RPC_value($a, $a_type);
> >          break;
> >         case 'object':
> >           $this->traceMessage('@OGoDocument:wrap.object');
> >           /// NOT SUPPORTED
> >          break;
> >         case 'resource':
> >           $this->traceMessage('@OGoDocument:wrap.resource');
> >           /// NOT SUPPORTED
> >          break;
> >         case 'NULL':
> >           $this->traceMessage('@OGoDocument:wrap.NULL');
> >           /// NOT SUPPORTED
> >          break;
> >        }
> >       return $value;
> >      }
> > 
> > .... which seems to be able to turn PHP structures into documents that
> > can be transported to a web service.