Re: [TCLCORE] TIP#239 Try/Catch/Finally syntax

[Joe E. <jen...@fl...>]

Neil Madden wrote:

> The try/handle (Twylite/JE) alternative would be:
>
>   proc async-foreach {varName list body} {
>       if {[llength $list] == 0} { return }
>       set list [lassign $list item]
>       try {
>           apply [list $varName $body] $item
>       } handle {code msg opts} {
>           switch $code {
>               3       { return }
>               0 - 4   { # ok/continue }
>               default { return -options $opts $msg }
>           }
>       }
>       after 0 [list async-foreach $varName $list $body]
>   }


A clarification: this is not what I proposed in [1].

In a clause like:

    handle {code ?resultVar ?optionsVar??} { script }

"code" would be an integer or a literal "ok"/"error"/etc.,
not a variable name.  Same as the

    catch code {?resultVar ?optionsVar??} { script }

form you proposed, just spelled slightly differently.


What I had in mind would look like:

    try {
	apply [list $varName $body] $item
    } handle return {
	return
    } handle ok {
    	# no-op
    } handle continue {
    	# no-op
    }

The clause "default { return -options $opts $msg }" from
the first script is unneeded, since that's the default
behaviour of [try] when no "handle" or "onerror" clause
matches.


--Joe English


[1] <URL: http://sourceforge.net/mailarchive/message.php?msg_name=E1L2s55-0001xW-6L%40eurydice.office.flightlab.com >