Version 10 of tailcall

Updated 2009-10-15 11:50:43 by jima

Like uplevel 1 except that it also causes the current scope to terminate, though the command is looked up in the current context first. Consequence of NRE.

 proc fred {} {
     george
 }

proc george {} {

 proc george {} {
      tailcall harry
 }

If I call fred, it's almost as though fred called harry directly, instead of george. Not so? MS: yup - all traces of george are gone from the program stack when harry is MS yup - all traces of george are gone from the program stack when harry is called. Now, if harry resolves to a different command in george's current namespace than it would under fred's, the harry that is called is george's and not fred's (no diff if the commands are FQ, of course). I think this does pretty much what delegation is supposed to do, right?


jima (2009-10-15) Perhaps this has been asked before or somewhere else... jima 2009-10-15: Perhaps this has been asked before or somewhere else...

I mean, once fred knows that has to call harry directly the bytecodes generated I mean, once fred knows that has to call harry directly the bytecodes generated would be the ones equivalent to have said:

 proc fred {} {
     harry
 }

I reckon I am not familiar with all the internals of Tcl but I find this would be an interesting thing. Wouldn't this be a new way to have some sort of macros? MS: Currently, tailcall is not bytecompiled. Everything happens at

AMG: Sounds a lot like exec in Unix shells. AMG: Sounds a lot like exec in Unix shells. See execline for more


See also TIP#327


Interaction with try

% proc foo {} {puts "I'm foo"}
% proc bar {} {puts "I'm bar"; try { tailcall foo } finally { puts "exitting" }}
I'm foo
% bar
I'm bar
exiting
exitting

31-03-2015 HE I'm sure ;-) that I don't understood what happend there. Why "exiting" is printed before "I'm foo" when I call bar?

wdb: Apparently, the tailcall closes one of the last gaps in