clarify the documentation on how to configure a cache implementation

use the popular cache::memcached::libmemcached as an example
the old code was throwing away the first error when creating a cache instance
(it did so using a list and a hashref as args); if the first failed, the 2nd
call would overwrite the first error. This is now fixed
the calling code wrapped the above code in an eval, and then silently discarded
the return value. This is now no longer the case, as the assumption of the code
was to have a working fallback, which is not currently implemented. This resulted
in a FIXME error on the first request to a controller using a cache->get or cache->set

diff --git a/lib/Catalyst/Plugin/Cache.pm b/lib/Catalyst/Plugin/Cache.pm
index ed606c5..22a9354 100644 (file)
--- a/lib/Catalyst/Plugin/Cache.pm
+++ b/lib/Catalyst/Plugin/Cache.pm
@@ -54,8 +54,18 @@ sub setup_cache_backends {
     }
 
     if ( !$app->get_cache_backend("default") ) {
-        local $@;
-        eval { $app->setup_generic_cache_backend( default => $app->get_default_cache_backend_config || {} ) };
+        ### XXX currently we dont have a fallback scenario
+        ### so die here with the error message. Once we have
+        ### an in memory fallback, we may consider silently
+        ### logging the error and falling back to that.
+        ### If we dont die here, the app will silently start
+        ### up and then explode at the first cache->get or
+        ### cache->set request with a FIXME error
+        #local $@;
+        #eval { 
+        $app->setup_generic_cache_backend( default => $app->get_default_cache_backend_config || {} );
+        #};
+        
    }
 }
 
@@ -81,11 +91,22 @@ sub setup_generic_cache_backend {
     my %config = %$config;
 
     if ( my $class = delete $config{class} ) {
-        eval { $app->setup_cache_backend_by_class( $name, $class, %config ) }
-            ||
-        eval { $app->setup_cache_backend_by_class( $name, $class, \%config ) }
-            ||
-        die "Couldn't construct $class with either list style or hash ref style param passing: $@";
+        
+        ### try as list and as hashref, collect the
+        ### error if things go wrong
+        ### if all goes well, exit the loop
+        my @errors;
+        for my $aref ( [%config], [\%config] ) {
+            eval { $app->setup_cache_backend_by_class( 
+                        $name, $class, @$aref 
+                    );
+            } ? do { @errors = (); last }
+              : push @errors, "\t$@";
+        }
+        
+        ### and die with the errors if we have any
+        die "Couldn't construct $class with either list style or hash ref style param passing:\n @errors" if @errors;
+        
     } elsif ( my $store = delete $config->{store} || $app->default_cache_store ) {
         my $method = lc("setup_${store}_cache_backend");
 
@@ -279,9 +300,17 @@ Catalyst::Plugin::Cache - Flexible caching support for Catalyst.
     # configure a backend or use a store plugin 
     __PACKAGE__->config->{cache}{backend} = {
         class => "Cache::Bounded",
-        # ... params ...
+        # ... params for Cache::Bounded...
     };
 
+    # typical example for Cache::Memcached::libmemcached
+    __PACKAGE__->config->{cache}{backend} = {
+        class   => "Cache::Memcached::libmemcached",
+        servers => ['127.0.0.1:11211'],
+        debug   => 2,
+    };
+
+
     # In a controller:
 
     sub foo : Local {