Does that make it more clear?

Nope. Just a big mess of unintelligible console output.

Returning a hashref from a subroutine is simple and straightforward:

%hash = ( subhash1 => { a=>1, b=>2 }, subhash2 => { c=>3, d=>4 } );;

sub getSubhash { 
    return $hash{ $_[0] } 
};;

pp getSubhash( 'subhash1' );;
{ a => 1, b => 2 }

pp getSubhash( 'subhash2' );;
{ c => 3, d => 4 }
[download]

Which means you must be doing something wrong.

So, how about you post:

• The source code of the subroutine or method that is (meant) to be returning the reference.
• The (actual) line of code that is calling it.

Then we'll be able to point out what you are doing wrong.

At the bottom of the call stack, is a 'Vars' routine to wrap fields in a hash. The relevant parts:

  sub _Var ($$$;$) {                          # Wrkhorse code for manu
+fctrd Vars
#note $p->obj, $vn=varname, $wa=wantarray val
    my ($__, $p, $vn, $wa)=@$_;
    $_=$__;                                  '$_'
    my $v   = $p->{$vn};                      # value
    my $rfv = ref $v;                         # type(ref) of var
   ......
      } elsif ($rfv == 'HASH') {             
        my $subvar=$arg;                 ## 1 var w/hash is is a key
        $p->{$vn}{$subvar}=$_[0] if @_;       ## another?  =>assign va
+lue
        return $p->{$vn}{$subvar};  <- returns has here.
[download]

That is called in sub 'by_mp' that takes care of init stuff and handles accessing the field: _by_mp in this case:

  sub by_mp(;$) { my $map = shift; my $c = ref $map || $map;
   ...init...

    my $arg_lvh = $map->_by_mp($arg);

    if (ref $arg_lvh) {
      $arg_lvh->fs_mp($arg);
      return $arg_lvh;    #<----seems to return from here
    }

    my $devno = (stat $arg)[0];

    $arg_lvh = $map->by_devno($devno);
    return undef unless $arg_lvh;
    die P "by_mp: by_devno(%s) returned %s, of type \"%s\", not a ref\
+n",
          $devno, $arg_lvh, ref $arg_lvh unless ref $arg_lvh;
    $map->_by_mp($arg, $arg_lvh);
    $arg_lvh->fs_mp($arg);
    return $arg_lvh;
  }
[download]

That is called in the level of code where I detect the problem:

  sub lvm_BaseDiff_Lvh_4_Base_opt_mp ($;$) {
    my $lvm = shift;
    my ($base_lvh, $lv_mp) = @_;
    my $diff_dev = pathcat("/dev", 
                  $base_lvh->vg_name, $base_lvh->lv_name . ".diff");
    #TPe "diff_dev=%s", $diff_dev;

# next is call to by_mp -- here is where I don't seem to be
#getting a reference back.


    my $bdiff_lvh = $lvm->by_mp($lv_mp.".diff") if @_;
    $bdiff_lvh = $lvm->by_devpath($diff_dev) unless ref $bdiff_lvh;
## commented version below was orig -- trying above -- 
## seems to work better, but seems a bit random...

    #my $bdiff_lvh = (@_ && $lvm->by_mp($lv_mp . ".diff") or
    #               $lvm->by_devpath($diff_dev));
    die P "Can't find \"diff\" dir for vol %s by mount or device path"
+, $lv_mp
      unless ref $bdiff_lvh;
    $bdiff_lvh->fs_mp($lv_mp) unless $bdiff_lvh->fs_mp;
    $bdiff_lvh->fs_type_name($base_lvh->fs_type_name) 
      unless $bdiff_lvh->fs_type_name;
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I have some doubts about the following code:

sub _Var ($$$;$) { # Wrkhorse code for manufctrd Vars
    #note $p->obj, $vn=varname, $wa=wantarray val
    my ($__, $p, $vn, $wa)=@$_;
[download]

1. Why are you using prototypes in the subroutine definition? Unless you have a very very good reason to use prototypes, you should not use prototypes. And using prototypes to check the type and number of arguments is not a good reason.
2. What do you think @$_ does? You are dereferencing the global default variable $_ into an array. Didn't you rather want to use the @_ variable which contains the parameters of the subroutine call?
3. Are you using strict and warnings?

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

My blog: Imperial Deltronics

Unless I am getting very short-sighted, _Var() is never called by either by_mp() or lvm_BaseDiff_Lvh_4_Base_opt_mp(), so why are you attributing the error to the return from that subroutine?

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

try changing

 } elsif ($rfv == 'HASH') {
[download]

to

 } elsif ($rfv eq 'HASH') {
[download]

poj