Better support for using field names and rule parameters in error messages.
diff --git a/system/language/english/form_validation_lang.php b/system/language/english/form_validation_lang.php
index 6afa37a..a1e0204 100644
--- a/system/language/english/form_validation_lang.php
+++ b/system/language/english/form_validation_lang.php
@@ -25,29 +25,29 @@
  * @filesource
  */
 
-$lang['required']			= "The %s field is required.";
-$lang['isset']				= "The %s field must have a value.";
-$lang['valid_email']		= "The %s field must contain a valid email address.";
-$lang['valid_emails']		= "The %s field must contain all valid email addresses.";
-$lang['valid_url']			= "The %s field must contain a valid URL.";
-$lang['valid_ip']			= "The %s field must contain a valid IP.";
-$lang['min_length']			= "The %s field must be at least %s characters in length.";
-$lang['max_length']			= "The %s field cannot exceed %s characters in length.";
-$lang['exact_length']		= "The %s field must be exactly %s characters in length.";
-$lang['alpha']				= "The %s field may only contain alphabetical characters.";
-$lang['alpha_numeric']		= "The %s field may only contain alpha-numeric characters.";
-$lang['alpha_dash']			= "The %s field may only contain alpha-numeric characters, underscores, and dashes.";
-$lang['numeric']			= "The %s field must contain only numbers.";
-$lang['is_numeric']			= "The %s field must contain only numeric characters.";
-$lang['integer']			= "The %s field must contain an integer.";
-$lang['regex_match']		= "The %s field is not in the correct format.";
-$lang['matches']			= "The %s field does not match the %s field.";
-$lang['is_unique'] 			= "The %s field must contain a unique value.";
-$lang['is_natural']			= "The %s field must contain only positive numbers.";
-$lang['is_natural_no_zero']	= "The %s field must contain a number greater than zero.";
-$lang['decimal']			= "The %s field must contain a decimal number.";
-$lang['less_than']			= "The %s field must contain a number less than %s.";
-$lang['greater_than']		= "The %s field must contain a number greater than %s.";
+$lang['required']			= 'The {field} field is required.';
+$lang['isset']				= 'The {field} field must have a value.';
+$lang['valid_email']		= 'The {field} field must contain a valid email address.';
+$lang['valid_emails']		= 'The {field} field must contain all valid email addresses.';
+$lang['valid_url']			= 'The {field} field must contain a valid URL.';
+$lang['valid_ip']			= 'The {field} field must contain a valid IP.';
+$lang['min_length']			= 'The {field} field must be at least {param} characters in length.';
+$lang['max_length']			= 'The {field} field cannot exceed {param} characters in length.';
+$lang['exact_length']		= 'The {field} field must be exactly {param} characters in length.';
+$lang['alpha']				= 'The {field} field may only contain alphabetical characters.';
+$lang['alpha_numeric']		= 'The {field} field may only contain alpha-numeric characters.';
+$lang['alpha_dash']			= 'The {field} field may only contain alpha-numeric characters, underscores, and dashes.';
+$lang['numeric']			= 'The {field} field must contain only numbers.';
+$lang['is_numeric']			= 'The {field} field must contain only numeric characters.';
+$lang['integer']			= 'The {field} field must contain an integer.';
+$lang['regex_match']		= 'The {field} field is not in the correct format.';
+$lang['matches']			= 'The {field} field does not match the {param} field.';
+$lang['is_unique'] 			= 'The {field} field must contain a unique value.';
+$lang['is_natural']			= 'The {field} field must contain only positive numbers.';
+$lang['is_natural_no_zero']	= 'The {field} field must contain a number greater than zero.';
+$lang['decimal']			= 'The {field} field must contain a decimal number.';
+$lang['less_than']			= 'The {field} field must contain a number less than {param}.';
+$lang['greater_than']		= 'The {field} field must contain a number greater than {param}.';
 
 
 /* End of file form_validation_lang.php */
diff --git a/system/libraries/Form_validation.php b/system/libraries/Form_validation.php
index 0a6a2af..ebd96e4 100644
--- a/system/libraries/Form_validation.php
+++ b/system/libraries/Form_validation.php
@@ -503,7 +503,7 @@
 				}
 
 				// Build the error message
-				$message = sprintf($line, $this->_translate_fieldname($row['label']));
+				$message = $this->_build_error_msg($line, $this->_translate_fieldname($row['label']));
 
 				// Save the error message
 				$this->_field_data[$row['field']]['error'] = $message;
@@ -651,7 +651,7 @@
 				}
 
 				// Build the error message
-				$message = sprintf($line, $this->_translate_fieldname($row['label']), $param);
+				$message = $this->_build_error_msg($line, $this->_translate_fieldname($row['label']), $param);
 
 				// Save the error message
 				$this->_field_data[$row['field']]['error'] = $message;
@@ -694,6 +694,27 @@
 	}
 
 	// --------------------------------------------------------------------
+	
+	/**
+	 * Build an error message using the field and param.
+	 *
+	 * @param	string	The error message line
+	 * @param	string	A field's human name
+	 * @param	mixed	A rule's optional parameter
+	 * @return	string
+	 */
+	protected function _build_error_msg($line, $field = '', $param = '')
+	{
+		// Check for %s in the string for legacy support.
+		if (strpos($line, '%s') !== false)
+		{
+			return sprintf($line, $field, $param);
+		}
+		
+		return str_replace(array('{field}', '{param}'), array($field, $param), $line);
+	}
+
+	// --------------------------------------------------------------------
 
 	/**
 	 * Get the value from a form