ASP Object
Objects are a way of
encapsulating multiple methods
(they're like functions) and
variables in one easy to manage
Uber-Variable (an Object). Objects
in ASP resemble other Object
Oriented Programming languages. In
this lesson we will be using the
ASP CDO.Message object as our
example object to be dissected.
ASP Object Overview
Objects were created to combat
the increasing complexity of
programming. The rationale for
understanding and using Objects in
your programming is to make
programming easier and your code
more human readable.
ASP Create an Object -
Server.CreateObject
An object in ASP is created by
passing a name string to the
Server.CreateObject
function(actually referred to as a
method). The string to create a
Message object is "CDO.Message".
We will be creating a CDO.Message
object in this example.
Note: Because objects are
special there is a special way
that you create and destroy them
using the Set keyword. These areas
are marked in red in the example
below.
ASP Code:
<%
Dim myObject
Set myObject =
Server.CreateObject("CDO.Message")
'You must Set your objects to
"nothing" to free up the
'the computer memory that was
allocated to it
Set myObject = nothing
%> |
That wasn't too painful, was
it? Let's cover some more bases on
the object model.
Objects are a collection of
related things that are combined
into this blob of programming goo
that can be created and destroyed
whenever we may need it. For
example say that you wanted to
make an object that allowed you to
send an email...
Well there are certain things
all emails have: To, From, CC,
Subject, etc. This list of
variables that are common to every
email would be quite tiresome to
have to create for every email we
sent. Wouldn't it be nice if we
could create some sort of
Uber-Variable(Object) that would
group all these smaller variables
into one thing?
ASP Object Properties
These smaller variables are
commonly referred to as an
object's properties and the format
for setting these properties is
nearly identical to setting a
variable equal to a value.
The correct syntax for setting
an object's properties is:
objectName.propertyName =
someValue
In this tiny example below we are
creating a new mail object and
setting its To and From
properties.
ASP Code:
<%
Dim myObject
Set myObject =
Server.CreateObject("CDO.Message")
'Then we set the To and From
properties
myObject.To = "little.timmy@example.com"
myObject.From = "huge.jill@example.com"
'You must Set your objects to
"nothing" to free up the
'the computer memory that was
allocated to it
Set myObject = nothing
%> |
Now I know we didn't DO
anything in the above example, but
we still need to learn a bit more
about objects before we can get
anything done! Objects, besides
having a clump of associated
common variables, may also have a
collection of functions(which
become referred to as methods)
associated with them.
These methods are processes
that you would want to commonly do
to either manipulate the variables
of the object or to use the
variables to do something. In our
Message object we have a
collection of information that,
when put together into the proper
email form and sent to an email
service will become an email.
All this complex code has been
programmed by Microsoft employees
and stored into the Message
objects Send method.
ASP Object Methods
We cannot see the code that was
used to program the Send method,
but that's one of the great things
about using object programming.
You know what you need to know and
nothing more. In our example below
we create a Message object and set
the necessary properties and send
it off with the Send method.
ASP Code:
<%
Dim myObject
Set myObject =
Server.CreateObject("CDO.Message")
'Then we set the To and From
properties
myObject.To = "little.timmy@example.com"
myObject.From = "huge.jill@example.com"
myObject.Subject = "Can you
see me?"
myObject.TextBody = "I'm
really really big!"
myObject.Send()
'You must Set your objects to
"nothing" to free up the
'the computer memory that was
allocated to it
Set myObject = nothing
%>
|
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