DZone Snippets: oop code

Javascript Ajax Object

pcx99 (Patrick) — Fri, 09 Mar 2007 03:06:18 GMT



// Just a stub function we'll tell ajaxObject to call when it's done

// callback functions get responseText, and responseStat respectively

// in their arguments.

function fin(responseTxt,responseStat) {

  alert(responseStat+' - '+responseTxt);

}



// create a new ajaxObject, give it a url it will be calling and

// tell it to call the function "fin" when its got data back from the server.

var test1 = new ajaxObject('http://someurl.com/server.cgi',fin);

    test1.update();

		

// create a new ajaxObject, give it a url and tell it to call fin when it

// gets data back from the server.  When we initiate the ajax call we'll

// be passing 'id=user4379' to the server.		

var test2 = new ajaxObject('http://someurl.com/program.php',fin);

    test2.update('id=user4379');

		

// create a new ajaxObject but we'll overwrite the callback function inside

// the object to more tightly bind the object with the response hanlder.

var test3 = new ajaxObject('http://someurl.com/prog.py', fin);

    test3.callback = function (responseTxt, responseStat) {

      // we'll do something to process the data here.

      document.getElementById('someDiv').innerHTML=responseTxt;

    }

    test3.update('coolData=47&userId=user49&log=true');	

		

// create a new ajaxObject and pass the data to the server (in update) as

// a POST method instead of a GET method.

var test4 = new ajaxObject('http://someurl.com/postit.cgi', fin);

    test4.update('coolData=47&userId=user49&log=true','POST');



function ajaxObject(url, callbackFunction) {

  var that=this;      

  this.updating = false;

  this.abort = function() {

    if (that.updating) {

      that.updating=false;

      that.AJAX.abort();

      that.AJAX=null;

    }

  }

  this.update = function(passData,postMethod) { 

    if (that.updating) { return false; }

    that.AJAX = null;                          

    if (window.XMLHttpRequest) {              

      that.AJAX=new XMLHttpRequest();              

    } else {                                  

      that.AJAX=new ActiveXObject("Microsoft.XMLHTTP");

    }                                             

    if (that.AJAX==null) {                             

      return false;                               

    } else {

      that.AJAX.onreadystatechange = function() {  

        if (that.AJAX.readyState==4) {             

          that.updating=false;                

          that.callback(that.AJAX.responseText,that.AJAX.status,that.AJAX.responseXML);        

          that.AJAX=null;                                         

        }                                                      

      }                                                        

      that.updating = new Date();                              

      if (/post/i.test(postMethod)) {

        var uri=urlCall+'?'+that.updating.getTime();

        that.AJAX.open("POST", uri, true);

        that.AJAX.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

        that.AJAX.send(passData);

      } else {

        var uri=urlCall+'?'+passData+'×tamp='+(that.updating.getTime()); 

        that.AJAX.open("GET", uri, true);                             

        that.AJAX.send(null);                                         

      }              

      return true;                                             

    }                                                                           

  }

  var urlCall = url;        

  this.callback = callbackFunction || function () { };

}

BlankSlate: Clean an object class to its bare minimum methods in Ruby

peter (Peter Cooperx) — Sun, 09 Apr 2006 23:46:48 GMT

From http://onestepback.org/index.cgi/Tech/Ruby/BlankSlate.rdoc

class BlankSlate

   instance_methods.each { |m| undef_method m unless m =~ /^__/ }

end

Lua: Descending Table Traversal Round 2: Iterator Object

kergoth (Chris Larson) — Mon, 05 Dec 2005 13:27:31 GMT

This is some concept code I threw together for Lua to see how feasable it was to make a lua object/table into an iterator that you can manipulate. This iterator descends through all tables and subtables of any queued table. It returns the "path" we're at, as a string, the current table, the key, and the value.

Code:

traverse = {}

function traverse:new(tname)

	local o = {}

	o.names = {}

	o.queue = {}

	o.cur = {

		tbl = nil,

		path = nil,

		state = nil,

	}



	local mt = {}

	function mt:__call(tn)

		return o:iter(tn)

	end

	mt.__index = self

	setmetatable(o, mt)



	if tname then

		o:enqueue(tname)

	end

	return o

end

function traverse:next()

	local v

	local names, queue, cur = self.names, self.queue, self.cur



	local function _poptbl()

		if cur.tbl then

			names[cur.tbl] = nil

		end

		cur.tbl = table.remove(queue, 1)

		cur.path = names[cur.tbl]

		cur.state = nil

	end



	repeat

		-- Find something to return to the user...

		if not cur.state then

			-- Pop a new table off the stack

			_poptbl()

			if not cur.tbl then

				-- No more tables to process

				return nil

			end

		end

		cur.state,v = next(cur.tbl, cur.state)

	until cur.state



	if type(v) == "table" then

		local path = cur.path.."."..cur.state

		names[v] = path

		table.insert(queue, v)

	end

	return cur.path,cur.tbl,cur.state,v

end

function traverse:iter(tname)

	if tname then

		self:enqueue(tname)

	end

	return function(...) return self:next(unpack(arg)) end, nil, nil

end

function traverse:enqueue(tname)

	local v = _G[tname]

	table.insert(self.queue, v)

	self.names[v] = tname

end

function traverse:reset()

	self.names = {}

	self.queue = {}

end

local traverse_mt = {

    __call = function(self, tname)

             	if tname then

             		return self:new(tname):iter()

             	else

             		return self:new()

             	end

             end

}

setmetatable(traverse, traverse_mt)

Example Usage:

foo = {a={},b={},c={"bar"},d={e={},f={"moo"}},1,2,3,4,5}

bar = {"alpha", "beta", "theta", omega = {}}



local mytraverser = traverse()

mytraverser:enqueue("bar")

mytraverser:enqueue("foo")

for p,t,k,v in mytraverser() do

--for p,t,k,v in traverse('foo') do

	print(string.format("%s[%s] = %s",tostring(p),tostring(k),tostring(v)))

end

Output from Example Usage:

bar[1] = alpha

bar[2] = beta

bar[3] = theta

bar[omega] = table: 0x510650

foo[1] = 1

foo[2] = 2

foo[3] = 3

foo[4] = 4

foo[5] = 5

foo[a] = table: 0x5102d0

foo[c] = table: 0x510370

foo[b] = table: 0x510320

foo[d] = table: 0x5103c0

foo.c[1] = bar

foo.d[e] = table: 0x5104c0

foo.d[f] = table: 0x510510

foo.d.f[1] = moo

PHP5 __sleep to handle superclasses' private members

tbarstow (Taylor) — Thu, 09 Jun 2005 00:44:16 GMT

PHP5 introduces visibility for object/class methods and data members. This can prove problematic when serializing objects because base classes cannot see their parents' private vars, so these can't be serialized. Plus, a base class probably doesn't know about all of its parents' private vars (even its public and protected ones). So, I use this:





class Object {

    function __sleep() {

        return array_keys( (array)$this );

    }

}



class BaseClass extends Object {

    private $foo;

    private $dbh; // some resource, like a database handler

    function __sleep() {

        unset($this->dbh);

        return parent::__sleep();

    }

}



class SubClass extends BaseClass {

    private $bar;

    function __sleep() {

        return parent::__sleep();

    }

}

The point is, the subclasses do any local cleanup then delegate the actual __sleep request to a parent class. With a common parent class Object that all other classes extend, we can keep the real serialize code in one place but still allow children to change their state before sleeping.

Flexible Singleton

drwitt (Carsten Witt) — Mon, 11 Apr 2005 05:52:59 GMT

PHP function Singleton allows you holding exactly one object of a class in memory. If an object of a given class doesn't exist, Singleton will create and store a new one in static array singleton. It then (and otherwise) will return a reference to it.

Adding an optional ID allows holding more than one object a class. Assigned ID will distinguish array keys.



/**

 * Singleton Repository

 * @param string $class PHP Class Name

 * @param string $id Optional Object ID

 * @return reference Reference to existing Object

 */

function &Singleton($class, $id='') {

  static $singleton = array();

  if (!array_key_exists($class.$id, $singleton))

    $singleton[$class.$id] = &new $class();

  $reference = &$singleton[$class.$id];

  return $reference;

}

Use like this:
[edit] I'm sorry there was a mistake in the first exmaple for three days or so. Fixed.



# first call: create object

$site_user=&Singleton('Student');

$site_user->Drink_Beer(5);



# second call: get a reference

$current_user=&Singleton('Student');

echo $current_user->Show_Beers_Counter();

#will be 5



#Two different objects

$one=&Singleton('Some_Class','one');

$two=&Singleton('Some_Class','two');

Works fine with PHP4, not tested on PHP5

generic object

tomp (tomp) — Fri, 08 Apr 2005 18:00:28 GMT

a generic object type thing for perl where you can use setanything and getanything to set and get properties via the AUTOLOAD method.



package thing;



use strict;



sub new {

	my %self;

	my ($class,@rest) = @_;

	unless ($#rest%2) { die "Odd parameter count\n"}

	for (my $k=0; $k<@rest; $k+=2) {

		my $wotsit = lc($rest[$k]);

		$wotsit =~ s/-//;

		$self{$wotsit} = $rest[$k+1];

		}

	bless \%self,$class;

}



sub AUTOLOAD {

        my ($where,$val) = @_;

        our $AUTOLOAD;

        $AUTOLOAD =~ s/.*://;

        my ($dirn,$what) = ($AUTOLOAD =~ /(...)(.*)/);

        if ($dirn eq "get") {

                return $$where{lc($what)};

        } elsif ($dirn eq "set") {

                $$where{lc($what)} = $val;

        }

        return 1;

}



1;

Here's a quick example of usage



use thing



$house = new thing("type","building","rooms",12,"foundations", "yes");



print $house -> gettype();

$house -> settype("tree");

print " " . $house -> gettype();

custom accessors

peter (Peter Cooperx) — Sat, 02 Apr 2005 19:39:31 GMT

class Song < ActiveRecord::Base

  # Uses an integer of seconds to hold the length of the song



  def length=(minutes)

    write_attribute("length", minutes * 60)

  end



  def length

    read_attribute("length") / 60

  end

end