Can I say its been great working with v4. I'm desperately trying to
use as much of the new functionality as possible but its hard as
there is so much to choose from!
Finally some feedback! I'm very happy you are enjoying it. I've put a
ton of stuff in that makes the overall experience so much more
pleasant. It's great being able to add things to the language.
1) To install the latest beta over the previous, should I follow
the instructions for "Updating an Existing A4D 3.0 Database.."
including deleting "forms, methods, style" or can I just use
Insider with moving preferences set to replace as previously? (BTW
This chapter is repeated twice in the latest reference pg 12 & pg 13)
Just copy the groups over the old groups. I'm totally bummed out --
somehow most of the changes I made to the Installation chapter got
lost. Oh well.
2) Lastly could you give us a clue to what you term "poor mans
classes". Maybe you could just provide a brief overview of the
how's and why's for syntax like "rs->GetRow".
Here's how it works in a nutshell. Let's say we want to create a new
class called Foo:
1. Create a library "Foo" that will act as the class.
2. Make one or more constructor methods (newFoo, newFooFromBar,
etc.). In the process of construction you create a collection which
becomes the "object". Make sure the collection has an item called
"__class__" whose name matches the library name.
3. If you want the object's data to be private (which you should,
good object-oriented design dictates you should force data access to
go through methods), prefix the key names with an underscore, that
prevents them from being accessed outside of the object's class/
library. So if the newFromBar() constructor took a bar parameter, you
would store it like this:
$object{"_bar"} := $inBar
4. Return the collection handle to the caller from the constructor,
that is the object reference.
5. The object methods must begin with a parameter called $self, which
will receive the "object" reference (which is actually a collection
handle). So you would have methods like this:
setBar($self; $inBar)
getBar($self)
6. Given an object reference, you can call a method on that object
using the dereference operator (this syntax is taken from C++, also
shared by PHP), like this:
$foo := Foo.newFromBar("foobar")
write($foo->getBar)
$foo->setBar("barfoo")
When Active4D sees ->, it transforms
$object->method(params)
internally into:
$object{"__class__"}.method($object; $params)
So here's our complete Foo class:
library "Foo"
method "new"
return (_init(""))
end method
method "newFromBar"($inBar)
return (_init($inBar))
end method
method "_init"($inBar)
$object := new collection("__class__"; current library name;
"_bar"; $inBar)
return ($object)
end method
method "setBar"($self; $inBar)
$self{"_bar"} := $inBar
end method
method "getBar"($self)
return ($self{"_bar"})
end method
You can look at the RowSet and Breadcrumb libraries to see a more
complex example.
Regards,
Aparajita
Victory-Heart Productions
www.aparajitaworld.com
"If you dare to fail, you are bound to succeed."
- Sri Chinmoy | www.srichinmoylibrary.com
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