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
[MS] As of today [tailcall] is not byte compiled, everything happens at runtime. That extremely simple example could indeed be bytecoded in a minute, but things get more involved as soon as [[fred]] has a bit more structure to it: arguments, local variables, namespace issues both for variable and command lookup, multiple exit points with different (or no) [tailcall] in them, etc.
[jima]: Thanks a lot Miguel for the answer. I see the point. I guess this is
[jima]: Thanks a lot Miguel for the answer. I see the point. I guess this is the same with uplevel 1, isn't it?

 proc fred {} {
  uplevel 1 {
   #code here
  }
 }

Would it be interesting to define a case (like a contract) saying if your proc is simple enough then it gets bytecompiled and you get some benefits?
[MS]:  you do not mean "bytecompiled" but rather "inlined into the caller", as

[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]#[http://tip.tcl.tk/327%|%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
!!!!!!
%| [Category Command] |%
!!!!!!