Introspection - how to get the value of a property in an instantiated class ?

General
1

Greetings all,

I have a class (dbEntry) which contains a bunch of properties; for this conversation it will have three = properties

  • name ( string)
  • street (string)
  • gender (string; M or F)

The class is instantiated in code and given values such as:-
dim ne as new dbEntry
ne.name = “Jim”
ne.street = “Avon”
ne.gender = “M”

Now I want to discover the properties in ne automatically, so that if I add another new property to dbEntry some time later, my code will deal with the new property without me having to write out in the code editor a list of all the properties in the class.

So I do this:
dim n as string
dim neProperties() as Introspection.PropertyInfo = Introspection.getType(ne).getProperties
for i as integer = 0 to uBound(neProperties)
n = neProperties(i).name
//here lives a function to write the name of each property of ne to a spreadsheet
next

This produces a list of the names of the properties in the object ne. All good.

Now I want to obtain the values of the property in this specific instantiated class. And here is where I have trouble.
What magical syntax allows me to find the value of ne.street ? (i.e." Avon") – when the code don’t ahead of time know that ne has a property named street ?

Introspection gives me the name of the new property ne.street … How do I get ne.street’s value ?

Note - street does not appear to be an “attribute” of ne, as mentioned in the LR for Introspection. street is a property of ne. Attributes seem to something else, only available by jumping through some hoops in the IDE.

Regards,
Tony Barry

2

First, please use the Code tags to format your code. It makes it easier for us to read that code and help.

In your loop:

for ...
  dim p as Introspection.PropertyInfo = neProperties( i )
  n = p.Name
  dim v as variant = p.Value( ne )
  ...

The array of properties belongs to the class, not the instance, so the Value function gets the property’s value from the instance you specify.

Also see:

http://developer.xojo.com/introspection