Re: FYI: ConditionalSet.pm

[Alexandre Duret-Lutz]

Hi Raja,

Thank you for proofreading me.

[...]

 Raja> This is "normalizing" the ConditionalSet in this special case.  Won't
 Raja> this cause loss of information?  Say:

 Raja> foo = 1
 Raja> if SOMECOND
 Raja> foo = 2
 Raja> endif

 Raja> Then variable_conditions('foo') should be ("TRUE", "SOMECOND_TRUE"),
 Raja> not ("TRUE"), I think.

I'm not too concerned by this because it shouldn't occur in
practice.  This double declaration of `foo' is disallowed
presently.

However I see no reason for this "normalization".  Maybe I thought
it would help in true().  (I wrote new() one month ago, and true()
today...)  Let's remove it.


Maybe we should allow this foo/foo construction in the future,
but in this case I think we should adjust the first foo's
condition when the second declaration is encountered.  So
variable_conditions('foo') would return ("SOMECOND_FALSE",
"SOMECOND_TRUE").

That day it will probably be a good idea to have a mechanism to
ensure that a set of conditions do not overlap.

[...]

 >> +      push (@ret, $c->merge_conds ($neg)) if $neg ne 'FALSE';
 Raja>                                         ^^^^^^^^^^^^^^^^^^
 Raja> If you don't let $cond be 'TRUE', this shouldn't be necessary.

I'll make a separate patch for this, as I'm not entirely sure I
understood what you meant.

[...]

Here is what I'm installing.

2002-11-14  Alexandre Duret-Lutz  <address@hidden>

        * automake.in (variable_defined): Thinko.
        * lib/Automake/ConditionalSet.pm (true): Simplify.
        (permutations): Fix documentation.
        (new): Don't simplify conditional sets that contain TRUE.
        Reported by Raja R Harinath.

Index: automake.in
===================================================================
RCS file: /cvs/automake/automake/automake.in,v
retrieving revision 1.1387
diff -u -r1.1387 automake.in
--- automake.in 14 Nov 2002 16:33:15 -0000      1.1387
+++ automake.in 14 Nov 2002 22:09:19 -0000
@@ -6531,7 +6531,7 @@
        if (exists $targets{$var}
            && (! defined $cond || exists $targets{$var}{$cond}))
          {
-           for my $tcond ($cond || ! target_conditions ($var)->false)
+           for my $tcond ($cond || target_conditions ($var)->conds)
              {
                prog_error ("\$targets{$var}{$tcond} exists but "
                            . "\$target_owner doesn't")
Index: lib/Automake/ConditionalSet.pm
===================================================================
RCS file: /cvs/automake/automake/lib/Automake/ConditionalSet.pm,v
retrieving revision 1.1
diff -u -r1.1 ConditionalSet.pm
--- lib/Automake/ConditionalSet.pm      14 Nov 2002 16:12:00 -0000      1.1
+++ lib/Automake/ConditionalSet.pm      14 Nov 2002 22:09:20 -0000
@@ -99,8 +99,7 @@
 
 As explained previously, the reference (object) returned is unique
 with respect to C<@conds>.  For this purpose, duplicate elements are
-ignored, and C<@conds> is rewriten as C<("TRUE")> if it contains
-C<"TRUE">.
+ignored.
 
 =cut
 
@@ -128,12 +127,6 @@
       # ConditionalSet as false for this reason.
       next if $cond->false;
 
-      # If we see true, then the whole set is true!
-      if ($cond->true && $#conds > 0)
-       {
-         return new Automake::ConditionalSet $cond;
-       }
-
       # Store conditions as keys AND as values, because blessed
       # objects are converted to string when used as keys (so
       # at least we still have the value when we need to call
@@ -218,10 +211,7 @@
 sub true ($ )
 {
   my ($self) = @_;
-  # To know whether a ConditionalSet covers all
-  # we invert it.  invert() will set $self->{'true'}.
-  $self->invert unless exists $self->{'true'};
-  return $self->{'true'};
+  return $self->invert->false;
 }
 
 =item C<$str = $set-E<gt>string>
@@ -292,14 +282,14 @@
 Calling $<$set-E<gt>permutations> will return the following Conditional set.
 
   new Automake::ConditionalSet
-    (new Automake::Conditional ("COND1_TRUE", "COND2_TRUE", "COND2_TRUE"),
-     new Automake::Conditional ("COND1_FALSE","COND2_TRUE", "COND2_TRUE"),
-     new Automake::Conditional ("COND1_TRUE", "COND2_FALSE","COND2_TRUE"),
-     new Automake::Conditional ("COND1_FALSE","COND2_FALSE","COND2_TRUE"),
-     new Automake::Conditional ("COND1_TRUE", "COND2_TRUE", "COND2_FALSE"),
-     new Automake::Conditional ("COND1_FALSE","COND2_TRUE", "COND2_FALSE"),
-     new Automake::Conditional ("COND1_TRUE", "COND2_FALSE","COND2_FALSE"),
-     new Automake::Conditional ("COND1_FALSE","COND2_FALSE","COND2_FALSE"));
+    (new Automake::Conditional ("COND1_TRUE", "COND2_TRUE", "COND3_TRUE"),
+     new Automake::Conditional ("COND1_FALSE","COND2_TRUE", "COND3_TRUE"),
+     new Automake::Conditional ("COND1_TRUE", "COND2_FALSE","COND3_TRUE"),
+     new Automake::Conditional ("COND1_FALSE","COND2_FALSE","COND3_TRUE"),
+     new Automake::Conditional ("COND1_TRUE", "COND2_TRUE", "COND3_FALSE"),
+     new Automake::Conditional ("COND1_FALSE","COND2_TRUE", "COND3_FALSE"),
+     new Automake::Conditional ("COND1_TRUE", "COND2_FALSE","COND3_FALSE"),
+     new Automake::Conditional ("COND1_FALSE","COND2_FALSE","COND3_FALSE"));
 
 =cut
 
@@ -372,11 +362,6 @@
   # It's tempting to also set $res->{'invert'} to $self, but that
   # isn't a bad idea as $self hasn't been normalized in any way.
   # (Different inputs can produce the same inverted set.)
-
-  # If $res is false, then $self covers all cases.  The true()
-  # method relies on this function to figure that.
-  $self->{'true'} = $res->false;
-
   return $res;
 }
 

-- 
Alexandre Duret-Lutz