allow providing your own stuff

.rubocop.yml

@@ -15,3 +15,5 @@ Style/StringLiterals:
   EnforcedStyle: double_quotes
 Gemspec/OrderedDependencies:
   Enabled: no
+Metrics/BlockLength:
+  Enabled: no

README.md

@@ -51,13 +51,13 @@ To validate strictly that the domain has an MX record:
 ```ruby
 validates :email, 'valid_email_2/email': { strict_mx: true }
 ```
-`strict_mx` and `mx` both default to a 5 second timeout for DNS lookups.  
+`strict_mx` and `mx` both default to a 5 second timeout for DNS lookups.
 To override this timeout, specify a `dns_timeout` option:
 ```ruby
 validates :email, 'valid_email_2/email': { strict_mx: true, dns_timeout: 10 }
 ```
 
-Any checks that require DNS resolution will use the default `Resolv::DNS` nameservers for DNS lookups.  
+Any checks that require DNS resolution will use the default `Resolv::DNS` nameservers for DNS lookups.
 To override these, specify a `dns_nameserver` option:
 ```ruby
 validates :email, 'valid_email_2/email': { mx: true, dns_nameserver: ['8.8.8.8', '8.8.4.4'] }
@@ -145,10 +145,19 @@ If you want to allow multibyte characters, set it explicitly.
 ValidEmail2::Address.permitted_multibyte_characters_regex = /[ÆæØøÅåÄäÖöÞþÐð]/
 ```
 
+If you want to load any of the lists dynamically:
+
+```ruby
+# make sure to use a Set for speedy access and cache the result
+ValidEmail2.disposable_proc = -> { Set.new(['your.com']) }
+ValidEmail2.deny_proc = -> { Set.new(['data.com']) }
+ValidEmail2.allow_proc = -> { Set.new(['provided.com']) }
+```
+
 ### Test environment
 
 If you are validating `mx` then your specs will fail without an internet connection.
-It is a good idea to stub out that validation in your test environment.  
+It is a good idea to stub out that validation in your test environment.
 Do so by adding this in your `spec_helper`:
 ```ruby
 config.before(:each) do
@@ -168,7 +177,7 @@ This gem is tested against currently supported Ruby and Rails versions. For an u
 
 In version v5.3.0 the config directory files were renamed as follows:
 
-`config/blacklisted_email_domains.yml` -> `config/deny_listed_email_domains.yml`  
+`config/blacklisted_email_domains.yml` -> `config/deny_listed_email_domains.yml`
 `config/whitelisted_email_domains.yml` -> `config/allow_listed_email_domains.yml`
 
 You won't need to make any changes yourself if you're installing this version for the first time. For individuals updating from earlier versions, make sure to update the file namings as per the above. In future versions this will be a breaking change.
@@ -178,7 +187,7 @@ You won't need to make any changes yourself if you're installing this version fo
 In version v3.0.0 I decided to move __and__ rename the config files from the
 vendor directory to the config directory. That means:
 
-`vendor/blacklist.yml` -> `config/blacklisted_email_domains.yml`  
+`vendor/blacklist.yml` -> `config/blacklisted_email_domains.yml`
 `vendor/whitelist.yml` -> `config/whitelisted_email_domains.yml`
 
 The `disposable` validation has been improved with a `mx` check. Apply the
@@ -187,7 +196,7 @@ down or if they do not work without an internet connection.
 
 ## Upgrading to v2.0.0
 
-In version 1.0 of valid_email2 we only defined the `email` validator.  
+In version 1.0 of valid_email2 we only defined the `email` validator.
 But since other gems also define a `email` validator this can cause some unintended
 behaviours and emails that shouldn't be valid are regarded valid because the
 wrong validator is used by rails.

lib/valid_email2.rb

@@ -7,17 +7,27 @@ module ValidEmail2
   ALLOW_LIST_FILE  = "config/allow_listed_email_domains.yml"
   DISPOSABLE_FILE = File.expand_path('../config/disposable_email_domains.txt', __dir__)
 
+  cattr_accessor :disposable_proc do
+    -> { @disposable_emails ||= load_file(DISPOSABLE_FILE) }
+  end
+  cattr_accessor :deny_proc do
+    -> { @deny_list ||= load_if_exists(DENY_LIST_FILE) || Set.new }
+  end
+  cattr_accessor :allow_proc do
+    -> { @allow_list ||= load_if_exists(ALLOW_LIST_FILE) || Set.new }
+  end
+
   class << self
     def disposable_emails
-      @disposable_emails ||= load_file(DISPOSABLE_FILE)
+      disposable_proc&.call
     end
 
     def deny_list
-      @deny_list ||= load_if_exists(DENY_LIST_FILE) || Set.new
+      deny_proc&.call
     end
 
     def allow_list
-      @allow_list ||= load_if_exists(ALLOW_LIST_FILE) || Set.new
+      allow_proc&.call
     end
 
     private
@@ -27,8 +37,7 @@ def load_if_exists(path)
     end
 
     def load_file(path)
-      # This method MUST return a Set, otherwise the
-      # performance will suffer!
+      # This method MUST return a Set, otherwise the performance will suffer!
       if path.end_with?(".yml")
         Set.new(YAML.load_file(path))
       else

spec/valid_email2_spec.rb

@@ -277,6 +277,22 @@ def set_allow_list
     end
   end
 
+  describe "with deny list validation" do
+    before do
+      @old_proc = ValidEmail2.deny_proc
+    end
+
+    after do
+      ValidEmail2.deny_proc = @old_proc
+    end
+
+    it "is invalid if the domain is deny-listed from a proc" do
+      ValidEmail2.deny_proc = -> { @deny_list ||= Set.new(['dubbi.com']) }
+      user = TestUserDisallowDenyListed.new(email: "foo@dubbi.com")
+      expect(user.valid?).to be_falsey
+    end
+  end
+
   describe "with mx validation" do
     it "is valid if mx records are found" do
       user = TestUserMX.new(email: "foo@gmail.com")