tcl command redirect to a variable, tcl version is 8.4

Question

I want to redirect the output of 1 command to a variable, where the OUTPUT is usually to STDOUT. I am running an EDA tool, which has tcl interpeter & it's own commands. Let's say that the tool has a tcl query, which says

TOOL> find_transistor m*
m1 m2 m3 m4

I want to have a way of doing the following:

TOOL> set ret redirect {find_transistor m*}
TOOL> puts $ret
m1 m2 m3 m4

Any ideas?

Answer 1

This might work:

redirect -variable ret {find_transistor m*}

puts $ret

Answer 2

If your application does not have a redirect command, you can create your own.

Please have a look at my answer to the more general question of how to redirect in plain Tcl?

To redirect into a variable you could do:

proc redirect_variable {varname cmd} {
    rename puts ::tcl::orig::puts

    global __puts_redirect
    set __puts_redirect {}

    proc puts args {
        global __puts_redirect
        set __puts_redirect [concat $__puts_redirect [lindex $args end]]
        set args [lreplace $args end end]
        if {[lsearch -regexp $args {^-nonewline}]<0} {
            set __puts_redirect "$__puts_redirect\n"
        }
        return
    }

    uplevel $cmd

    upvar $varname destination
    set destination $__puts_redirect
    unset __puts_redirect

    rename puts {}
    rename ::tcl::orig::puts puts
}

Answer 3

I tried everything mentioned here. Finally this is the one that actually worked for me:

redirect -variable <myvar> {puts [<some_tcl_command>] }
puts $<myvar>

PS: This worked in a Cadence tool.

Answer 4

well in pure Tcl

set ret [find_transistor m*]

would probably do what you want. Try reading the Tcl tutorial.