Known problems with Cost 2.2

Platform-specific

I've successfully built Cost 2.2 on most of the platforms which I have available, but there have been a few snags:

• Under Red Hat Linux release 5.2 (Tcl/Tk 8.0.3), costsh and costwish coredump with a segmentation fault in Tcl_SetupEnv() on startup. package require Cost appears to work, though, and under Red Hat 5.0 (Tcl/Tk patch level 8.0) everything works fine. Haven't tracked this one down yet.
• Update: Compiling on a different RedHat 5.2 box, it seems to work. The only difference between the two systems that seems to be relevant is: compiling with egcs-2.90.29 980515 (egcs-1.0.3 release), the application crashes; compiling with gcc version 2.7.2.3, it works. Further experimentation reveals that this problem isn't specific to Cost: I can't build any Tcl shell with egcs.
• Under IRIX 5.2 with Tcl/Tk patch level 8.1.0, costsh failed to locate the Tcl shared library libtcl8.1.so; strangely, costwish ran without problems. The solution I found was to change tcl8.1/unix/Makefile to read:

  ${TCL_LIB_FILE}: ${OBJS} ${STUB_LIB_FILE}
  	rm -f ${TCL_LIB_FILE}
  	${SHLIB_LD} -o ${TCL_LIB_FILE} ${OBJS} -rpath ${LIB_RUNTIME_DIR}
  	$(RANLIB) ${TCL_LIB_FILE}
  

  (that is: adding -rpath ${LIB_RUNTIME_DIR} to the link line), then recompiling and reinstalling libtcl8.1.so.

  Adding this flag when building costsh would probably also work, but ${LIB_RUNTIME_DIR} doesn't seem to be available to autoconf or in tclConfig.sh

Miscellaneous goofs

Most of these have been fixed in Cost 2.2 patchlevel 1.

• Stub support was never tested and was totally broken. Should be fixed now.
• Package cleanup code was freeing the same data multiple times. This could lead to a coredump/GPF when the program exits. Fixed now.
• make install doesn't install the binaries costsh and costwish. You have to type make install-bin instead, and that doesn't work, either. Fixed now.
• An assertion in tclcost.c had the sense of the test reversed; compiling with -DASSERTIONS is guaranteed to cause problems. Fixed now.
• Core.tcl was hardcoded to call sgmls, even though most everybody uses nsgmls now. Fixed now: by default, loaddoc will call nsgmls instead, and you can set the environment variable $COST_PARSER to override it if desired.
• Had removed textutils.tcl and auxfile.tcl from the distribution on the grounds that they were undocumented and not terribly well thought-out. Put them back in, since it turns out a few people were using them.

Building under Windows

I've had absolutely no luck with this. I suppose I ought to just break down and buy a copy of M*cr*s*ft Visual C++, but I'd really rather stick with gcc if possible.

Progress so far:

• It looks like the stub library is the way to go.
• I found a file called gccstubs.zip somewhere on Neosoft, which looks like it might be helpful.
• The Cygwin documentation page has a document describing the black magic for building a DLL with the Cygwin tools. Update: Mumit Khan has some much more helpful stuff. Update: The incantation given in the Cygwin Project Faq ("How do I build a relocatable DLL") finally seems to have worked.
• Compiling with -DUSE_TCL_STUBS -mdll -mno-cygwin, and building the dll with -ltclstub81 -lmsvcrt -lkernel32 seems to have worked. (Not sure if -lkernel32 is necessary).
• Scriptics has a HOWTO describing the black magic needed to build a Windows Extension, and one describing the black magic needed to use Stubs.
• Cygwin Beta 20 compiles all the source without problems, but it won't link or run.

Now I just need to put all the pieces together, probably with the aid of a RITA, used in accordance with section 3.2 of RFC 2321.

Update, 1 Jul 1999: After another late night of hacking, I got a working costsh.exe (built on top of the Cygtcl libraries), and a non-working cost2.2.dll built with the Stubs library (the .dll links, but it crashes tclsh when loaded). (Update 1, er, 2 Jul 1999 Got the .DLL working. Going to bed now.)

Open Questions

How should selectNode, selectDocument, withNode, and withDocument interact?

In Cost, the current node is a property of the state of the system. Now that Cost supports multiple documents, it may be desirable to associate a current node with each document. Right now, selectDocument and withDocument always set the current node to the root of the new document, but it may be useful for them to set the current node to ``where you left off.'' The question is: when and where should the document current node be set and restored?

My current thinking is to have withNode and foreachNode work as at present -- that is, only set the application current node -- and have selectNode set both the application current node and the document current node. selectDocument will return to the last node selected by selectNode.

It would also be useful for selectDocument and withDocument to take an optional query; that way you could combine:

withDocument $doc1 {
    withNode subtree element FOO {
	... 
    }
}

withDocument $doc1 subtree element FOO {
    ...
}

Will have to experiment with this further to see what the Right Thing is.

Unicode support

NSGMLS, EXPAT, and Tcl 8.1+ all support Unicode, so there's really no reason why Cost shouldn't be able to as well. I haven't looked into this yet. Any advice would be appreciated. The only real constraint is that I'd like to maintain compatibility with Tcl 7.5 through 8.0 without too many #ifdefs.

XML support/EXPAT integration

I really haven't tested this very thouroughly yet.

Problems encountered so far:

• [21 Jul 1999]: query attval foo doesn't work if the attribute name is not all-uppercase.
• There are probably more case-sensitivity problems lurking.
• PIs and entity references are not supported.