Feature Request: lappend return index

Difference between version 0 and 5 - Previous - Next

**Feature Request**

`lappend` is a wonderful command to append to a tcl-list. The problem is to get the '''index''' of the last insert.
I Use this`lappend` to convert and ''handle'' into a ''number'' and return the ''number'' to an ''external'' ressource
****Old Code****

======
  # factory startup (constructor)
  constructor {{tmpl ""}} {
    next $tmpl
    my ConfigSetServerSetup serverSetup
    my variable LcConfigC_Idx
    set LcConfigC_Idx -1
  }

  method LcConfigC_WriteHDL { hdl } {
    my variable  LcConfigC_Handle LcConfigC_Idx
    lappend LcConfigC_Handle $hdl
    incr LcConfigC_Idx
  }
======

As you see to return the ''index'' it is required to maintain a '''second''' variable (in my case `LcConfigC_Idx`) and init the
'''second''' variable in the `constructor` to `-1`

**Sol*Feature Requestion***

please add an `-index` option to `lappend` just to return the ''index'' of the new created element and '''not''' the whole list.

****New Code****

======
  # factory startup (constructor)
  constructor {{tmpl ""}} {
    next $tmpl
    my ConfigSetServerSetup serverSetup
  }

  method LcConfigC_WriteHDL { hdl } {
    my variable  LcConfigC_Handle
    lappend -index LcConfigC_Handle $hdl
  }
======
****add-on****

multiple arguments to `lappend -index` should return a ''list-of-indexes''

======
set hdlLst {a b c}
lappend -index hdlLst d e f
> 3 4 5
======

possible but '''not''' beautiful solution with '''single''' `lappend` without using `LcConfigC_Idx`,

======
  method LcConfigC_WriteHDL { hdl } {
    my variable  LcConfigC_Handle
    lappend LcConfigC_Handle $hdl
    expr {[llength $LcConfigC_Handle]-1}
  }
======