How to store a list in a dictionary?

I am trying to work with the layoutswitched event in VBA. What I would like to do is store a list of layers that are on and not frozen in a viewport. I did this with A2002 using Ldata, but we are moving to 2005 and that mehod is out. So, is there a good method for storing a list and associating it with a viewport?

 

Hi,

You should be able to do this quite easily by created a new dictionary and
storing the layer name data as a comma separated string, from which you can
easily return it to an array with the Split command.

You will find sample code for all you need in the help files.

--


Laurie Comerford
CADApps
www.cadapps.com.au

like to do is store a list of layers that are on and not frozen in a
viewport. I did this with A2002 using Ldata, but we are moving to 2005 and
that mehod is out. So, is there a good method for storing a list and
associating it with a viewport?

 

Pardon this, but let's not promote unsound practices like
name-based references. The people who designed AutoCAD's
database gave a lot of thought to this, and it would be good
if programmers took advantage of it.

For starters, if you persist references to layers by storing
their names as strings, AutoCAD doesn't know they're layer
names.

Practically, what that means is that if a user were to
subsequently RENAME a layer,your string contining the old
layer name is no longer valid.

A reference to a layer can be stored in XDATA, or as an
object ID reference in an xrecord, in a way that is not
name-dependent.

"Name-dependent reference", means that a reference to
something like a layer, is made by storing the name of the
referenced object.

Name-dependent references are bad.

In contrast, a name-independent reference is where somthing
in a draiwng is referenced by storing something other than the
referenced object's name, such as its object id.

The important thing about that is that if a user renames
something that is referenced by its name, the reference is
broken.

Conversely, if a reference to something is not name-dependent
(e.g., via object an id), the reference is not broken when the
referenced object's name is changed.

 

You can store layer names in extended entity data, or
you can store the object ids of layers in an xrecord that
is stored in the viewport's extension dictionary.

The bad thing about storing the names of layers is that
the layers can be renamed. In that case, you would no
longer have a valid reference. By storing the object id
of a layer (or a layer in the xdata layer group), you do
not have to concern yourself with breaking references
if a layer is renamed.

This is certainly not as easy as LDATA or storing a comma
delimited string somewhere. I've found that more often
than not, the easiest way to do something is also not the
best/proper way. I've also found that when you take the
easy way out, you don't realize that it was a bad decision
until its way too late to do an about-face.

You will need to familiarize yourself with XRECORDS and/or
XDATA to do this. XRecords are generally a better way to
attach data to objects, in contrast to LDATA.

If you're unsure about how to proceed, feel free to
post back, and/or search the newsgroups using keys like
'XRECORD', SetXRecordData, GetXRecordData, etc.