revert previous patch for a much safer version

Author: faxm0dem

README.md

@@ -132,15 +132,29 @@ cpan {'DBD::DB2':
 
 Some modules like `Sys::RunAlone` don't return a code 0 when invoked with `perl -M$MODULE_NAME -e1`.
 This means there's no way for puppet to check if they're installed or not (in an agnostic way).
-Therefore you'll have to override the method. Use the `%` sign if you need the module name in the command line.
+Therefore you'll have to change the `exists_strategy`:
 
 ```puppet
 cpan {'Sys::RunAlone':
   ensure => 'present',
-  exists_command => 'perl -M% -e"__END__"',
+  exists_strategy => 'find',
 }
 ```
 
+Currently two strategies are implemented:
+
+#### include (default)
+
+Tries to include module:
+
+```
+perl -M$MODULE_NAME
+```
+
+#### find
+
+Tries to find module in `@INC` list much like `pmpath` is doing.
+
 ## Reference
 
 ## Classes

lib/puppet/provider/cpan/default.rb

@@ -46,9 +46,14 @@ def create
       system("#{umask} yes | perl #{ll} -MCPAN -e 'CPAN::install #{resource[:name]}'")
     end
 
-    exists_command = "perl #{ll} -M#{resource[:name]} -e1 > /dev/null 2>&1"
-    if resource[:exists_command]
-      exists_command = resource[:exists_command].gsub(/\%/,resource[:name])
+    case resource[:exists_strategy]
+    when :find
+      # stolen from pmtools/pmpath
+      # will not work on windows
+      # use Module::Find maybe instead
+      exists_command = "perl #{ll} -e '$module=#{resource[:name]}; eval \"local \\$^W = 0; require $module\";for ($shortpath = $module) {s{::}{/}g;s/$/.pm/;}if (defined($INC{$shortpath})) {exit 0;}; exit 2'"
+    else
+      exists_command = "perl #{ll} -M#{resource[:name]} -e1 > /dev/null 2>&1"
     end
     system(exists_command)
     estatus = $?.exitstatus
@@ -91,9 +96,14 @@ def exists?
     if resource[:local_lib]
       ll = "-Mlocal::lib=#{resource[:local_lib]}"
     end
-    exists_command = "perl #{ll} -M#{resource[:name]} -e1 > /dev/null 2>&1"
-    if resource[:exists_command]
-      exists_command = resource[:exists_command].gsub(/\%/,resource[:name])
+    case resource[:exists_strategy]
+    when :find
+      # stolen from pmtools/pmpath
+      # will not work on windows
+      # use Module::Find maybe instead
+      exists_command = "perl #{ll} -e '$module=#{resource[:name]}; eval \"local \\$^W = 0; require $module\";for ($shortpath = $module) {s{::}{/}g;s/$/.pm/;}if (defined($INC{$shortpath})) {exit 0;}; exit 2'"
+    else
+      exists_command = "perl #{ll} -M#{resource[:name]} -e1 > /dev/null 2>&1"
     end
     Puppet.debug(exists_command)
     output = `#{exists_command}`

lib/puppet/type/cpan.rb

@@ -38,11 +38,10 @@
     end
   end
 
-  newparam(:exists_command) do
-    desc 'Custom command to test for module existence'
-    validate do |value|
-      raise ArgumentError, 'String expected for exists_command.' unless value.is_a?(String)
-    end
+  newparam(:exists_strategy) do
+    defaultto "include"
+    newvalues("include", "find")
+    desc 'Strategy to test for module existence'
   end
 
   newparam(:force, :boolean => true, :parent => Puppet::Parameter::Boolean) do

test/exists_command.pp

@@ -5,7 +5,19 @@
 }
 
 cpan { 'Sys::RunAlone':
-  ensure         => present,
-  exists_command => 'perl -Mlocal::lib=/tmp/cpan -M% -e"__END__"',
-  local_lib      => '/tmp/cpan',
+  ensure          => present,
+  exists_strategy => 'find',
+  local_lib       => '/tmp/cpan',
+}
+
+cpan { 'Class::AccessorMaker':
+  ensure          => present,
+  exists_strategy => 'find',
+  local_lib       => '/tmp/cpan',
+}
+
+cpan { 'Riemann::Client':
+  ensure          => present,
+  exists_strategy => 'include',
+  local_lib       => '/tmp/cpan',
 }