DN535292596

Subject: Re: Bug Tcl 8.2 Should link with -rdynamic option on FreeBSD 3.2+ - DN [1]

Paul Duffin <pduffin@mailserver.hursley.ibm.com> - 11 Oct 1999 - comp.lang.tcl

 Roger E Critchlow Jr wrote:
 >
 > Paul Duffin <pduffin@mailserver.hursley.ibm.com> writes:
 >
 > >
 > >                                                        I would recommend
 > > that you try and rebuild your extension using the stub interface as this
 > > has many advantages.
 > >
 >
 >  Http://www.scriptics.com/services/support/howto/stubs.html lists two
 > advantages:
 >
 >         1) stubbed extensions run with different versions of Tcl.
 >         2) stubbed extensions run with statically linked tclsh's.
 >
 > Those are good reasons to use stubs, but they don't sound like "many"
 > advantages.
 >
 > Are there others?  Where are they listed?  This was the only page that
 > searching scriptics for "stubs" found.
 >

 Here are the reasons given in the announcement I made at the beginning of the
 year.

 1)  Adds support for backlinking to all platforms, thus making it possible
     for static executables to dynamically load extensions on any platform.

 2)  Eliminates all the operating system specific problems associated with
     dynamically linking an extension to Tcl/Tk and any other library which
     exports a stub interface. This may sound like a wild claim but it is
     true simply because the operating system does not have to do anything.

 3)  Extensions and libraries built with different compilers will work
     together even if it is not possible to link them normally. The only
     requirement for them to be able to work together is that function calls
     are compatible.

 4)  As extensions do not have a hard coded reference to the library it is
     possible to use them with any library which is compatible. e.g. an
     extension which was originally built for Tcl 8.0 should work with Tcl
     8.1, and an extension built for Tcl 8.1 could work with Tcl 8.0.

 And after some experience with backlinking and how it actually works I would
 say that stubs provides a *superior* backlinking mechanism to that which
 exists on any platform because symbol clashes across components have no
 effect.

 --
 Paul Duffin
 DT/6000 Development    Email: pduffin@hursley.ibm.com
 IBM UK Laboratories Ltd., Hursley Park nr. Winchester
 Internal: 7-246880    International: +44 1962-816880