Does Class Exist

[michaelk]

Is there a way to check to see if a class with a string name exists in the drawing?

...other than using ClassNum to get the total number of classes and ClassList() to check each class?

Thanks

mk

[Miguel Barrera]

1. Check total number of existing classes

2. Create class by calling NameClass(className)

3. Get class total again

4. If both totals are the same, the class exists and vs sets it as the active class. If second total increases, then the class does not exist and the new class becomes the active one.

[Pat Stanford]

Miguels suggestion works if you know the whole name of the class. If you want to get classes whose name CONTAINS a substring I think you will have to loop through the class list.

I just tried ForEachObject and it appears to filter out classes.

It also appears that using '*' as a wildcard in a N='*None*' for example, does not return anything unless there is a character before the None while the final * allows for a zero length string.

I am filing a bug.

[michaelk]

Thanks, gentlemen.

I'm trying to avoid creating a class every time a script is run by checking first to see if the class exists. Sounds like Miguel's solution will work great.

MK

[Pat Stanford]

From the VW2011 VS Function Reference:

PROCEDURE NameClass

( className:STRING ) ;

Description:

Creates a new class in a Vectorworks document, which then become the active class.

If the specified class already exists, then it will become the active class of the document.

Note: Class names cannot exceed 20 characters.

If you use NameClass, it does not matter if it exists or not, it will simple become active.

Probably faster/easier to just get the active class, NameClass, reset active class than check for existance.

[michaelk]

Pat

I'm actually trying to create the classes if they don't exist and set all of their by class attributes.

I think I understand most of it - except for textures.

There is a SetClUseTexture (boolean) but no GetClUseTexture. Am I missing something?

And how does one set which texture to use?

Thanks

MK

[JBenghiat]

I always thought you could use IF GetObject(ClassName)=NIL... I believe this has worked for me in the past. You could also confirm type 94.

I believe layers are the only handles you can't get with GetObject, and they have their own call.

-Josh

[C. Andrew Dunning]

Michael -

Here is a Function that I use that I believe Gerard Jonker wrote a while ago that does exactly what you're needing, assuming you know the name of the Class:

{----- Function to Determine Existence of Given Class -----}

function existclass(Cstr : string) : boolean;

var

ci:longint;

stop:boolean;

begin

ci:=0;

stop:=false;

while stop=false do

begin

ci:=ci+1;

if Cstr = classlist(ci) then

begin

stop:= true;

existclass:=true;

end;

if ci = classnum then stop:=true;

end;

end;

If the Class doesn't exist, you can then store the active Class, create the new one and set it's attributes, and then "reactivate" the stored Class.

[michaelk]

Thanks all. That's three ways of checking the existence of a class that would not have occurred to me.

Does anyone have a way of setting the default texture of a class?

MK

[C. Andrew Dunning]

Michael -

I could be incredibly wrong, here - and haven't tried this, but would using SetTextureRef w. the Class' handle work?

[michaelk]

I'll give it a shot.

Thanks.

[cadtischler]

Hello,

an alternative Version for the Test:

FUNCTION ClassExistTest(s:STRING):BOOLEAN;

VAR l:LONGINT;

BEGIN

ClassExistTest:=FALSE;

FOR l:=1 TO ClassNum DO IF ClassList(l)=s THEN ClassExistTest:=TRUE;

END;