Created Oddmuse::Storage::Delegate and use it

META6.json

@@ -47,6 +47,7 @@
     "Oddmuse::Save":                "lib/Oddmuse/Save.pm6",
     "Oddmuse::Secret":              "lib/Oddmuse/Secret.pm6",
     "Oddmuse::Storage":             "lib/Oddmuse/Storage.pm6",
+    "Oddmuse::Storage::Delegate":   "lib/Oddmuse/Storage/Delegate.pm6",
     "Oddmuse::Storage::File":       "lib/Oddmuse/Storage/File.pm6",
     "Oddmuse::Storage::File::Lock": "lib/Oddmuse/Storage/File/Lock.pm6",
     "Oddmuse::View":                "lib/Oddmuse/View.pm6"

lib/Oddmuse/Storage.pm6

@@ -14,6 +14,8 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program. If not, see <https://www.gnu.org/licenses/>.
 
+use Oddmuse::Storage::Delegate;
+
 =begin pod
 
 =head1 Oddmuse::Storage
@@ -70,7 +72,7 @@ C<templates> subdirectory with the <sp6> extension.
 class Oddmuse::Storage {
     my $class = %*ENV<ODDMUSE_STORAGE> || 'Oddmuse::Storage::File';
     require ::($class);
-    has $!delegate handles <
+    has Oddmuse::Storage::Delegate $!delegate handles <
         get-page put-page get-keep-page put-keep-page
         put-change get-changes get-current-revision
         lock-page unlock-page is-locked

lib/Oddmuse/Storage/Delegate.pm6

@@ -0,0 +1,82 @@
+# Oddmuse is a wiki engine
+# Copyright (C) 2018  Alex Schroeder <alex@gnu.org>
+#
+# This program is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Affero General Public License as published by the
+# Free Software Foundation, either version 3 of the License, or (at your
+# option) any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License
+# for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+use Oddmuse::Page;
+use Oddmuse::Change;
+use Oddmuse::Filter;
+
+=begin pod
+
+=head1 Oddmuse::Storage::Delegate
+
+Any module implementing the L<Oddmuse::Storage> layer must "do" this
+role.
+
+=end pod
+
+#| Storage layer role
+role Oddmuse::Storage::Delegate {
+
+    #| Return a new Page.
+    multi method get-page(Str $id!, Bool $is-admin --> Oddmuse::Page) is export {
+        return Oddmuse::Page.new();
+    }
+
+    #| Return a new Page, assume no admin permissions
+    multi method get-page(Str $id! --> Oddmuse::Page) {
+        return Oddmuse::Page.new();
+    }
+
+    #| Save a Page.
+    method put-page(Oddmuse::Page $page! --> Nil) is export {
+    }
+
+    #| Get an old revision, or the current page if it doesn't exist.
+    method get-keep-page(Str $id!, Int $n! --> Oddmuse::Page) is export {
+        return Oddmuse::Page.new();
+    }
+
+    #| Save new revision of a page and return the revision number.
+    method put-keep-page(Str $id! --> Int) is export {
+        return 0;
+    }
+
+    #| Add a Change to the log.
+    method put-change(Oddmuse::Change $change! --> Nil) is export {
+    }
+
+    #| Get the changes matching a filter from the log file.
+    method get-changes(Oddmuse::Filter $filter! --> List) is export {
+        return ();
+    }
+
+    #| Get the current revision for a page.
+    method get-current-revision(Str $id! --> Int) is export {
+        return 0;
+    }
+
+    #| Lock a page.
+    method lock-page(Str $id! --> Nil) is export {
+    }
+
+    #| Unlock a page.
+    method unlock-page(Str $id! --> Nil) is export {
+    }
+
+    #| Is this page locked?
+    method is-locked(Str $id! --> Bool) is export {
+    }
+}

lib/Oddmuse/Storage/File.pm6

@@ -17,6 +17,7 @@
 use Oddmuse::Page;
 use Oddmuse::Change;
 use Oddmuse::Filter;
+use Oddmuse::Storage::Delegate;
 use Oddmuse::Storage::File::Lock;
 
 =begin pod
@@ -43,7 +44,7 @@ C<Oddmuse::Storage::File::Lock>.
 =end pod
 
 #| Implement storage layer using files.
-class Oddmuse::Storage::File {
+class Oddmuse::Storage::File does Oddmuse::Storage::Delegate {
 
     my $SEP = "\x1e"; # ASCII UNIT SEPARATOR