Re: [Xotcl] Creating objects from C

From: Gustaf Neumann <neumann_at_wu-wien.ac.at>
Date: Sat, 28 Oct 2006 01:34:47 +0200

Scott,

good points. One can create an uninitialized object in XOTcl using the
"alloc" method.
So, the best approach for the current versions is

   1) alloc object
   2) set the defaults
   3) call configure
   4) call init

in the prerelase of xotcl 1.5.3, (2) can be achieved by the new
"initslots" method, in earlier versions
this is more tricky than needed. Since you are creating the object from
C, you don't need (3),
maybe you don't even need (2). If this is the case, you just need

   callmethod yourclass alloc name
   obj = getobject(name)
   setobjclientdata obj cd
   callmethod obj init

That should be actually slightly faster than the current createobject
interface.
If you don't need the default values, this works with already with 1.5.2,
otherwise you need the prerelease.

You find the prerelease under
http://media.wu-wien.ac.at/download/xotcl-1.5.3-alpha2.tar.gz
I made this version available for the heated discussion about tip257 vs.
tip279
http://www.tcl.tk/cgi-bin/tct/tip/279.html

i am leaving tomorrow morning for one week to the US, so i might not be
able to answer
mails for one week.

-gustaf

PS: simplifying this on the c-interface is still a good idea.



Scott Gargash schrieb:
>
> When creating XOTcl objects from C, it would be nice to be able to
> initialize the new object's clientData prior to any methods being
> invoked on the object.
>
> Right now, the only way I can think of to do this is to
> 1. create the object (which invokes "init", which can't rely on the
> ClientData)
> 2. XOTclSetObjectClientData( XOTclGetObject(), data); // Or the Class
> equivalent
> 3. Invoke some secondary, private "init"-like method that does true
> initialization
>
> It would be nice to have two new exported functions:
>
> int XOTclCreateObjectCl (Tcl_Interp* in, Tcl_Obj* name, ClientData
> data, struct XOTcl_Class* cl);
> int XOTclCreateClassCl (Tcl_Interp* in, Tcl_Obj* name, ClientData
> data, struct XOTcl_Class* cl);
>
> That initialize the XOTcl ClientData field prior to invoking "init" so
> that "init" could rely on the XOTcl ClientData being valid. This
> would make it much easier to construct XOTcl wrappers around C/C++
> objects.
>
> Is this reasonable? Is there a better way to accomplish this?
>
> Scott
>
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