+=head2 ambient_pragmas
+
+ $deparse->ambient_pragmas(strict => 'all', '$[' => $[);
+
+The compilation of a subroutine can be affected by a few compiler
+directives, B<pragmas>. These are:
+
+=over 4
+
+=item *
+
+use strict;
+
+=item *
+
+use warnings;
+
+=item *
+
+Assigning to the special variable $[
+
+=item *
+
+use integer;
+
+=item *
+
+use bytes;
+
+=item *
+
+use utf8;
+
+=item *
+
+use re;
+
+=back
+
+Ordinarily, if you use B::Deparse on a subroutine which has
+been compiled in the presence of one or more of these pragmas,
+the output will include statements to turn on the appropriate
+directives. So if you then compile the code returned by coderef2text,
+it will behave the same way as the subroutine which you deparsed.
+
+However, you may know that you intend to use the results in a
+particular context, where some pragmas are already in scope. In
+this case, you use the B<ambient_pragmas> method to describe the
+assumptions you wish to make.
+
+Not all of the options currently have any useful effect. See
+L</BUGS> for more details.
+
+The parameters it accepts are:
+
+=over 4
+
+=item strict
+
+Takes a string, possibly containing several values separated
+by whitespace. The special values "all" and "none" mean what you'd
+expect.
+
+ $deparse->ambient_pragmas(strict => 'subs refs');
+
+=item $[
+
+Takes a number, the value of the array base $[.
+
+=item bytes
+
+=item utf8
+
+=item integer
+
+If the value is true, then the appropriate pragma is assumed to
+be in the ambient scope, otherwise not.
+
+=item re
+
+Takes a string, possibly containing a whitespace-separated list of
+values. The values "all" and "none" are special. It's also permissible
+to pass an array reference here.
+
+ $deparser->ambient_pragmas(re => 'eval');
+
+
+=item warnings
+
+Takes a string, possibly containing a whitespace-separated list of
+values. The values "all" and "none" are special, again. It's also
+permissible to pass an array reference here.
+
+ $deparser->ambient_pragmas(warnings => [qw[void io]]);
+
+If one of the values is the string "FATAL", then all the warnings
+in that list will be considered fatal, just as with the B<warnings>
+pragma itself. Should you need to specify that some warnings are
+fatal, and others are merely enabled, you can pass the B<warnings>
+parameter twice:
+
+ $deparser->ambient_pragmas(
+ warnings => 'all',
+ warnings => [FATAL => qw/void io/],
+ );
+
+See L<perllexwarn> for more information about lexical warnings.
+
+=item hint_bits
+
+=item warning_bits
+
+These two parameters are used to specify the ambient pragmas in
+the format used by the special variables $^H and ${^WARNING_BITS}.
+
+They exist principally so that you can write code like:
+
+ { my ($hint_bits, $warning_bits);
+ BEGIN {($hint_bits, $warning_bits) = ($^H, ${^WARNING_BITS})}
+ $deparser->ambient_pragmas (
+ hint_bits => $hint_bits,
+ warning_bits => $warning_bits,
+ '$[' => 0 + $[
+ ); }
+
+which specifies that the ambient pragmas are exactly those which
+are in scope at the point of calling.
+
+=back
+