all dataflow ops now work as lvalues

Author: mohawk2

Changes

@@ -7,7 +7,7 @@
 - t_quartic now exported, and with a correct inverse
 - add %PDL::{Math,Ops}::got_complex to record whether have complex versions
 - MatrixOps::svd now handles transpose transparently
-- Ops::{re,im} now work as lvalues
+- all ops with two-way dataflow now work as lvalues
 
 2.103 2026-03-03
 - fix regression in *linvals so takes ndarrays as start and end again

lib/PDL/Ops.pd

@@ -414,7 +414,6 @@ PDL_IF_BAD(if ( \$ISBAD(complexv()) ) \$SETBAD(b()); else,)
 	   !$backcode ? () : (
 	     DefaultFlow => 1,
 	     TwoWay => 1,
-	     Lvalue => 1,
 	     BackCode => pp_line_numbers(__LINE__-1, qq{
 		PDL_IF_BAD(if ( \$ISBAD(b()) ) \$SETBAD(complexv()); else {,)
 		   $backcode

lib/PDL/PP.pm

@@ -1488,6 +1488,7 @@ EOF
      }),
    PDL::PP::Rule::Returns->new("OverloadDocValues", []),
 
+   PDL::PP::Rule::Returns::One->new('Lvalue', 'TwoWay', 'TwoWay => Lvalue'),
    PDL::PP::Rule->new([qw(UsageDoc ParamDoc)],
      [qw(Name Doc? SignatureObj OtherParsDefaults? ArgOrder?
        OverloadDocValues InplaceDocValues ParamDesc? Lvalue? NoExport?
@@ -2013,11 +2014,11 @@ EOF
       sub {make_xs_code('','',@_)}),
 
    PDL::PP::Rule->new("VTableDef",
-      ["VTableName","ParamStructType","RedoDimsFuncName","ReadDataFuncName",
-       "WriteBackDataFuncName","FreeFuncName",
-       "SignatureObj","HaveBroadcasting","NoPthread","Name",
-       "GenericTypes","IsAffineFlag","TwoWayFlag","DefaultFlowFlag",
-       "BadFlag"],
+      [qw(VTableName ParamStructType
+       RedoDimsFuncName ReadDataFuncName WriteBackDataFuncName FreeFuncName
+       SignatureObj HaveBroadcasting NoPthread Name
+       GenericTypes IsAffineFlag TwoWayFlag DefaultFlowFlag
+       BadFlag)],
       sub {
         my($vname,$ptype,$rdname,$rfname,$wfname,$ffname,
            $sig,$havebroadcasting, $noPthreadFlag, $name, $gentypes,

lib/PDL/PP.pod

@@ -2627,6 +2627,7 @@ first argument's C<copy> method will be used.
 
 If true, sets in the C<pdl_transvtable> (see L<PDL::Internals>) the
 C<iflags> such as to inform the trans's error checks connected to dataflow.
+As of 2.104, also automatically sets C<Lvalue>.
 
 =head3 Identity
 
@@ -2665,6 +2666,7 @@ Example:
 
 If present, make the operation's XS function be C<lvalue>, like
 L<PDL::Slices/xchg>. Added in 2.096.
+As of 2.104, automatically set if C<TwoWay>.
 
 =head1 Appendix B: PP macros and functions
 

lib/PDL/Slices.pd

@@ -151,7 +151,6 @@ pp_def('index',
        HandleBad => 1,
        DefaultFlow => 1,
        TwoWay => 1,
-       Lvalue => 1,
        Pars => 'a(n); indx ind(); [oca] c();',
        Code =>
        $index_init . ' $c() = $a(n => this_ind);',
@@ -167,7 +166,6 @@ pp_def('index1d',
        HandleBad => 1,
        DefaultFlow => 1,
        TwoWay => 1,
-       Lvalue => 1,
        Pars => 'a(n); indx ind(m); [oca] c(m);',
        Code => pp_line_numbers(__LINE__, <<'EOF'),
          loop(m) %{
@@ -216,7 +214,6 @@ pp_def('index2d',
        HandleBad => 1,
        DefaultFlow => 1,
        TwoWay => 1,
-       Lvalue => 1,
        Pars => 'a(na,nb); indx inda(); indx indb(); [oca] c();',
        Code =>
        $index2d_init . pp_line_numbers(__LINE__-1, ' $c() = $a(na => this_ind_a, nb => this_ind_b);'),
@@ -582,7 +579,6 @@ avoiding the perl argument-parsing step.
 EOD
         HandleBad => 1,
         TwoWay => 1,
-        Lvalue => 1,
         P2Child => 1,
 
 # rdim: dimensionality of each range (0 dim of index PDL)
@@ -1416,7 +1412,6 @@ EOF
 pp_def('xchg',
         OtherPars => 'PDL_Indx n1; PDL_Indx n2;',
         TwoWay => 1,
-        Lvalue => 1,
         P2Child => 1,
         AffinePriv => 1,
         EquivDimCheck =>pp_line_numbers(__LINE__, <<'EOF'),
@@ -1581,7 +1576,6 @@ EOD
 pp_def('mv',
         OtherPars => 'PDL_Indx n1; PDL_Indx n2;',
         TwoWay => 1,
-        Lvalue => 1,
         P2Child => 1,
         AffinePriv => 1,
         CHeader => <<'EOF',
@@ -1857,7 +1851,6 @@ Put some dimensions to a broadcastid.
 EOD
         P2Child => 1,
         TwoWay => 1,
-        Lvalue => 1,
         AffinePriv => 1,
         OtherPars => "PDL_Indx id; PDL_Indx whichdims[]",
         Comp => 'PDL_Indx nrealwhichdims',
@@ -1938,7 +1931,6 @@ See [TBD Doc] for details and examples.
 EOD
         P2Child => 1,
         TwoWay => 1,
-        Lvalue => 1,
         AffinePriv => 1,
         OtherPars => 'PDL_Indx atind;',
         RedoDims => pp_line_numbers(__LINE__, <<'EOF'),

t/pp_pod.t

@@ -155,6 +155,19 @@ subtest a_bl => sub {
     ok all_seen($obj, 'foo'), 'all seen';
 };
 
+subtest a_bt => sub {
+    my $obj = call_pp_def(foo =>
+      Pars => 'a(n); [o]b(n)',
+      TwoWay => 1,
+    );
+    ok find_usage($obj, '$b = foo($a)'), 'function call w/ arg';
+    ok find_usage($obj, 'foo($a, $b)'), 'all arguments given';
+    ok find_usage($obj, '$b = $a->foo'), 'method call';
+    ok find_usage($obj, '$a->foo($b)'), 'method call, arg';
+    ok find_usage($obj, '$a->foo .= $data'), 'method call, twoway as lvalue';
+    ok all_seen($obj, 'foo'), 'all seen';
+};
+
 subtest a_b_k => sub {
     my $obj = call_pp_def(foo =>
         Pars => 'a(n); [o]b(n)',