File::CheckTree hates @'s

[perl5.git] / lib / attributes.pm

diff --git a/lib/attributes.pm b/lib/attributes.pm
index d26872f..4f6eef0 100644 (file)
--- a/lib/attributes.pm
+++ b/lib/attributes.pm
@@ -1,6 +1,6 @@
 package attributes;
 
-$VERSION = 0.02;
+our $VERSION = '0.04_01';
 
 @EXPORT_OK = qw(get reftype);
 @EXPORT = ();
@@ -27,13 +27,13 @@ sub carp {
 #
 # The extra trips through newATTRSUB in the interpreter wipe out any savings
 # from avoiding the BEGIN block.  Just do the bootstrap now.
-BEGIN { bootstrap }
+BEGIN { bootstrap attributes }
 
 sub import {
     @_ > 2 && ref $_[2] or do {
        require Exporter;
        goto &Exporter::import;
-    }
+    };
     my (undef,$home_stash,$svref,@attrs) = @_;
 
     my $svtype = uc reftype($svref);
@@ -54,7 +54,7 @@ sub import {
                my $s = ((@pkgattrs == 1) ? '' : 's');
                carp "$svtype package attribute$s " .
                    "may clash with future reserved word$s: " .
-                   join(' , ' , @pkgattrs);
+                   join(' : ' , @pkgattrs);
            }
        }
     }
@@ -65,7 +65,7 @@ sub import {
        croak "Invalid $svtype attribute" .
            (( @badattrs == 1 ) ? '' : 's') .
            ": " .
-           join(' , ', @badattrs);
+           join(' : ', @badattrs);
     }
 }
 
@@ -98,7 +98,7 @@ attributes - get/set subroutine or variable attributes
 =head1 SYNOPSIS
 
   sub foo : method ;
-  my ($x,@y,%z) : Bent ;
+  my ($x,@y,%z) : Bent = 1;
   my $s = sub : method { ... };
 
   use attributes ();   # optional, to get subroutine declarations
@@ -120,11 +120,14 @@ the following:
 
 The second example in the synopsis does something equivalent to this:
 
-    use attributes __PACKAGE__, \$x, 'Bent';
-    use attributes __PACKAGE__, \@y, 'Bent';
-    use attributes __PACKAGE__, \%z, 'Bent';
+    use attributes ();
+    my ($x,@y,%z);
+    attributes::->import(__PACKAGE__, \$x, 'Bent');
+    attributes::->import(__PACKAGE__, \@y, 'Bent');
+    attributes::->import(__PACKAGE__, \%z, 'Bent');
+    ($x,@y,%z) = 1;
 
-Yes, that's three invocations.
+Yes, that's a lot of expansion.
 
 B<WARNING>: attribute declarations for variables are an I<experimental>
 feature.  The semantics of such declarations could change or be removed
@@ -137,7 +140,18 @@ directly by this module, depending on how you look at it.)  However,
 package-specific attributes are allowed by an extension mechanism.
 (See L<"Package-specific Attribute Handling"> below.)
 
-The setting of attributes happens at compile time.  An attempt to set
+The setting of subroutine attributes happens at compile time.
+Variable attributes in C<our> declarations are also applied at compile time.
+However, C<my> variables get their attributes applied at run-time.
+This means that you have to I<reach> the run-time component of the C<my>
+before those attributes will get applied.  For example:
+
+    my $x : Bent = 42 if 0;
+
+will neither assign 42 to $x I<nor> will it apply the C<Bent> attribute
+to the variable.
+
+An attempt to set
 an unrecognized attribute is a fatal error.  (The error is trappable, but
 it still stops the compilation within that C<eval>.)  Setting an attribute
 with a name that's all lowercase letters that's not a built-in attribute
@@ -169,10 +183,19 @@ This has a meaning when taken together with the B<locked> attribute,
 as described there.  It also means that a subroutine so marked
 will not trigger the "Ambiguous call resolved as CORE::%s" warning.
 
+=item lvalue
+
+Indicates that the referenced subroutine is a valid lvalue and can
+be assigned to. The subroutine must return a modifiable value such
+as a scalar variable, as described in L<perlsub>.
+
 =back
 
 There are no built-in attributes for anything other than subroutines.
 
+=for hackers
+What about C<unique>?
+
 =head2 Available Subroutines
 
 The following subroutines are available for general use once this module
@@ -267,7 +290,8 @@ will use that package name.
 =head2 Syntax of Attribute Lists
 
 An attribute list is a sequence of attribute specifications, separated by
-whitespace, commas, or both.  Each attribute specification is a simple
+whitespace or a colon (with optional whitespace).
+Each attribute specification is a simple
 name, optionally followed by a parenthesised parameter list.
 If such a parameter list is present, it is scanned past as for the rules
 for the C<q()> operator.  (See L<perlop/"Quote and Quote-like Operators">.)
@@ -275,8 +299,8 @@ The parameter list is passed as it was found, however, and not as per C<q()>.
 
 Some examples of syntactically valid attribute lists:
 
-    switch(10,foo(7,3)) , ,  expensive
-    Ugly('\(") , Bad
+    switch(10,foo(7,3))  :  expensive
+    Ugly('\(") :Bad
     _5x5
     locked method
 
@@ -286,7 +310,7 @@ Some examples of syntactically invalid attribute lists (with annotation):
     Ugly('(')                  # ()-string not balanced
     5x5                                # "5x5" not a valid identifier
     Y2::north                  # "Y2::north" not a simple identifier
-    foo + bar                  # "+" neither a comma nor whitespace
+    foo + bar                  # "+" neither a colon nor whitespace
 
 =head1 EXPORTS
 
@@ -322,7 +346,8 @@ Code:
 
 Effect:
 
-    use attributes Canine => \$spot, "Watchful";
+    use attributes ();
+    attributes::->import(Canine => \$spot, "Watchful");
 
 =item 2.
 
@@ -333,7 +358,8 @@ Code:
 
 Effect:
 
-    use attributes Felis => \$cat, "Nervous";
+    use attributes ();
+    attributes::->import(Felis => \$cat, "Nervous");
 
 =item 3.