HaO 2014-01-29: (to be removed) I started this page due to lack of information how to handle NRE for commands implemented in C. I would be glad, if this page could be populated by people having more knowledge about the issue. The following information comes from this clt communication from Miguel Sofer and Donal Fellows:
I have some commands in a dll which are typically created in the Dllname_Init using:
Tcl_CreateObjCommand(Interp, "cmd", cmdProc, NULL, NULL);
I want to use them with tcl8.6 and I am thinking if it is wise/necessary to modify them to be NRE enabled.
Thus, the upper has to be replaced by:
Tcl_NRCreateCommand(Interp, "cmd", cmdProc, cmdNREProc, NULL, NULL);
Then there is an example on: [L1 ] but I am really lost there.
Thus my questions:
If yes, under which circumstances ?
It is only a good idea if:
If either of those two conditions are not met, you are much better off NOT NRE-enabling your commands - you'd just be paying the cost with zero benefits.
Note that 8.6 properly runs all 8.5 C-extensions (assuming they do not use internal headers, in which case it's a "maybe").
I suppose a NRE enabled dll is not usable with tcl 8.5.x. Is there a way to make a dll working on tcl 8.5 and 8.6 nre enabled
Yes. Compile using stubs against 8.6's tcl.h, and switch at runtime between 8.5 or 8.6 code depending on (for instance) the existence of the command yield.
I am sorry, the wiki example did not help me understanding what to do. Is there any way.
Plenty of those in the 8.6 sources. I suggest starting with something simple, for instance catch. Compare the 8.5 and 8.6 implementations in tclCmdAH.c
Answer moved on [L2 ].