added more constructors to AMQP::Envelope

include/amqpcpp/envelope.h

@@ -53,8 +53,19 @@ public:
      *  @param  size
      */
     Envelope(const char *body, uint64_t size) : MetaData(), _body(body), _bodySize(size) {}
+    Envelope(const std::string_view &body) : Envelope(body.data(), body.size()) {}
     Envelope(const char *body) : Envelope(body, strlen(body)) {}
     
+    /**
+     *  Constructor that preserves meta-data, but installs different body
+     *  @param  metadata
+     *  @param  body
+     *  @param  size
+     */
+    Envelope(const MetaData &metadata, const char *body, uint64_t size) : MetaData(metadata), _body(body), _bodySize(size) {}
+    Envelope(const MetaData &metadata, const std::string_view &body) : Envelope(metadata, body.data(), body.size()) {}
+    Envelope(const MetaData &metadata, const char *body) : Envelope(metadata, body, strlen(body)) {}
+
     /**
      *  Read envelope frmo an input-buffer
      *  This method is the counterpart of the Envelope::fill() method, and is not used

include/amqpcpp/metadata.h

@@ -4,7 +4,7 @@
  *  With every published message a set of meta data is passed to. This class
  *  holds all that meta data.
  *
- *  @copyright 2014 - 2017 Copernica BV
+ *  @copyright 2014 - 2023 Copernica BV
  */
 
 /**
@@ -127,14 +127,12 @@ protected:
     ShortString _clusterID;
 
 
+public:
     /**
-     *  Protected constructor to ensure that this class can only be constructed
-     *  in a derived class
+     *  Constructor for empty meta data. Can be useful when user-space wants to preserve all meta-data
      */
     MetaData() {}
 
-
-public:
     /**
      *  Read incoming frame
      *  @param  frame