'''[http://www.tcl.tk/man/tcl/TclCmd/copy.htm%|%oo::copy]''', a [Tcl
commands%|%built-in] [Tcl] command, creates a duplicate of a [TclOO] object.



** Documentation **

   [http://www.tcl.tk/man/tcl/TclCmd/copy.htm%|%official reference]:   



**  Synopsis **

    :   '''oo::copy''' ''sourceObject'' ?''targetObject''?



** Description **

'''oo::copy''' duplicates structure of an object and then calls an internal
method of the ''created'' object, '''`<cloned>`''', with the source object as an
argument,  which sets up any advanced properties of the created object based on
the source object. The default implementation of that method in the
[oo::object] class copies [procedure%|%procedures] and [variable%|%variables] from the source object's
[namespace], but does ''not'' copy any traces or [command%|%commands] implemented in [C].

Objects can potentially refuse to be duplicated, generating an [error] instead.
Generating an error from the '''`<cloned>`''' method counts as refusal.



** Wrapper That Respects [namespace import%|%Imported] [proc%|%Procedures] **

`[oo::object] <cloned>` copies aliased procedures in the origin namespace over
to the new namespace as native procedures.  The following drop-in replacement
changes that behaviour so that imported procedures are imported procedures in
the new namespace as well.  The code below is not necessarily recommended, as
overriding `<cloned>` in a subclass is the recommended way of getting this
behaviour.

======
rename copy oocopy
proc copy {sourceObject args} {
    set from [uplevel [list namespace which $sourceObject]]
    set fromns [info object namespace $from]
    if {[string range $fromns end-1 end] eq {::}} {
        set fromns [string range $fromns 0 end-2]
    }
    set to [uplevel [list [namespace current]::oocopy $from {*}$args]]
    set tons [info object namespace $to]
    foreach proc [info procs ${tons}::*] {
        set tail [namespace tail $proc]
        if {[namespace origin ${fromns}::$tail] ne "${fromns}::$tail"} {
            #For imported procedures ::oo::copy doesn't import the procedure
            #but creates an entirely new equivalent procedure in the new
            #namespace. This is probably not what's desired.  Delete the proc
            #that oo::copy made so that copycommands can just make an
            #equivalent import
            rename $proc {}
        }
    }
    copycommands $fromns $tons my
    return $to
}
======




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