Add B::Deparse->ambient_pragmas_from_caller helper shortcut

Author: leonerd

lib/B/Deparse.pm

@@ -7,7 +7,7 @@
 # This is based on the module of the same name by Malcolm Beattie,
 # but essentially none of his code remains.
 
-package B::Deparse 1.87;
+package B::Deparse 1.88;
 use strict;
 use Carp;
 use B qw(class main_root main_start main_cv svref_2object opnumber perlstring
@@ -1068,6 +1068,16 @@ sub ambient_pragmas {
     $self->{'ambient_hinthash'} = $hinthash;
 }
 
+sub ambient_pragmas_from_caller {
+    my $self = shift;
+    my ($hint_bits, $warning_bits, $hinthash) = (caller(0))[8, 9, 10];
+    $self->ambient_pragmas(
+        hint_bits    => $hint_bits,
+        warning_bits => $warning_bits,
+        '%^H'        => $hinthash,
+    );
+}
+
 # This method is the inner loop, so try to keep it simple
 sub deparse {
     my $self = shift;
@@ -7393,7 +7403,8 @@ They exist principally so that you can write code like:
     ); }
 
 which specifies that the ambient pragmas are exactly those which
-are in scope at the point of calling.
+are in scope at the point of calling.  However, see also
+L</ambient_pragmas_from_caller>.
 
 =item %^H
 
@@ -7402,6 +7413,16 @@ stored in the special hash %^H.
 
 =back
 
+=head2 ambient_pragmas_from_caller
+
+    $deparse->ambient_pragmas_from_caller()
+
+A convenient shortcut for setting the hints and warnings ambient pragmas to
+those of the immediately calling code.  This uses the
+L<caller|perlfunc/caller> function to determine the hints and warnings bits in
+effect at the callsite to this method, and sets those as the ambient settings
+for the deparser.
+
 =head2 coderef2text
 
     $body = $deparse->coderef2text(\&func)

lib/B/Deparse.t

@@ -67,15 +67,7 @@ while (<DATA>) {
 
     my $code = "$meta{context};\n" . <<'EOC' . "sub {$input\n}";
 # Tell B::Deparse about our ambient pragmas
-my ($hint_bits, $warning_bits, $hinthash);
-BEGIN {
-    ($hint_bits, $warning_bits, $hinthash) = ($^H, ${^WARNING_BITS}, \%^H);
-}
-$deparse->ambient_pragmas (
-    hint_bits    => $hint_bits,
-    warning_bits => $warning_bits,
-    '%^H'        => $hinthash,
-);
+$deparse->ambient_pragmas_from_caller;
 EOC
     my $coderef = eval $code;
 
@@ -103,17 +95,7 @@ EOC
 }
 
 # Reset the ambient pragmas
-{
-    my ($b, $w, $h);
-    BEGIN {
-        ($b, $w, $h) = ($^H, ${^WARNING_BITS}, \%^H);
-    }
-    $deparse->ambient_pragmas (
-        hint_bits    => $b,
-        warning_bits => $w,
-        '%^H'        => $h,
-    );
-}
+$deparse->ambient_pragmas_from_caller;
 
 use constant 'c', 'stuff';
 is((eval "sub ".$deparse->coderef2text(\&c))->(), 'stuff',