tcl port and thread anabling

[Gustaf Neumann]

Dear MacPorts gurus,

Currently i am in the process of preparing several new ports 
that depend on a tcl with threads enabled. The current 
situation in MacPorts is that the thread-enabled version of 
tcl is a variant (ports install tcl +threads). This has 
several implications

a) Since one cannot depend on a variant, one has to document 
"prior to installation of this package, please install tcl 
with ports enabled". The expectation of a package user of a 
package depending on a threaded tcl (e.g. currently the port 
"aolserver") is that a "port install aolserver" does 
everything required.

One could add e.g. a pre-configure section to the 
thread-dependent package and bail out, when the installed 
tcl is not thread enabled and to install the proper 
"variant". This is at least bettern than crashing.

b) When a non-threaded tcl is installed, and one wants to 
"upgrade" to the threaded tcl, one has recompile all 
packages with thread support. if one has e.g. installed tcl 
without threads, installed then the port "xotcl" (which has 
thread support) then one should re-build xotcl based on the 
threaded install. Otherwise loads of the non-threaded 
xotcl-extension in a multithreaded tcl app (e.g. aolserver) 
will cause crashes (missing mutex protection). Similarly, 
even loads of non-thread-compiled tcl-dependent packages 
compiled without thread support can cause crashes when 
loaded into a thread-enabled tclsh. see [1]. Is there a 
recommended way to automate reinstallation? Are there other 
recommendations or other experiences from other ports?

The simplest approach is to ship tcl by default with threads 
enabled. While Tcl 8.4 was distributed on many platforms 
with threads disabled by default, this has changed with Tcl 
8.5 (out since several years). Tcl 8.5 is shipped threaded 
by several distributions such as ActiveState [2] (all builds 
are threaded for Windows, Mac OS X and Unix), Redhat and 
Debian (up to my knowledge). The tcl portfile has a warning 
inside about threaded builds, but that might be a left-over 
from Tcl 8.4.

Any recommendations for (a) and (b)?

-gustaf neumann

[1] 
http://community.activestate.com/forum-topic/activetcl-non-thread-version-8-4-15
[2] http://wiki.tcl.tk/1875

PS: i am currently preparing ports for

tdom
naviserver
naviserver-libthread
naviserver-ndbpg
naviserver-smtpd

and maybe more.