## NAME

DwMsgId -- Class representing an RFC-822 msg-id

## SYNOPSIS

    class DW_EXPORT DwMsgId : public DwFieldBody {

    public:

        DwMsgId();
        DwMsgId(const DwMsgId& aMsgId);
        DwMsgId(const DwString& aStr, DwMessageComponent* aParent=0);
        virtual ~DwMsgId();
        const DwMsgId& operator = (const DwMsgId& aMsgId);
        virtual void Parse();
        virtual void Assemble();
        virtual DwMessageComponent* Clone() const;
        virtual void CreateDefault();
        const DwString& LocalPart() const;
        void SetLocalPart(const DwString& aLocalPart);
        const DwString& Domain() const;
        void SetDomain(const DwString& aDomain);
        static DwMsgId* NewMsgId(const DwString& aStr,
            DwMessageComponent* aParent);
        static DwMsgId* (*sNewMsgId)(const DwString&, DwMessageComponent*);
        static const char* sHostName;

    public:

        virtual void PrintDebugInfo(ostream& aStrm, int aDepth=0) const;
        virtual void CheckInvariants() const;

    protected:

        void _PrintDebugInfo(ostream& aStrm) const;
    };

## DESCRIPTION

`DwMsgId` represents a msg-id as described in RFC-822. In the BNF grammar in RFC-822, a msg-id has a local-part and a domain. In MIME++, a `DwMsgId` contains strings that contain the local-part and the domain.

In the tree (broken-down) representation of message, a `DwMsgId` object may only be a leaf node, having a parent but no child nodes. Its parent node must be a `DwField` object.

`DwMsgId` has member functions for getting or setting its local-part and its domain. You can have the library to create the contents of a `DwMsgId` object for you by calling the member function `CreateDefault()`.

## Public Member Functions

DwMsgId()
DwMsgId(const DwMsgId& aMsgId)
DwMsgId(const DwString& aStr, DwMessageComponent* aParent=0)

The first constructor is the default constructor, which sets the `DwMsgId` object's string representation to the empty string and sets its parent to NULL.

The second constructor is the copy constructor, which performs a deep copy of `aMsgId`. The parent of the new `DwMsgId` object is set to NULL.

The third constructor copies `aStr` to the `DwMsgId` object's string representation and sets `aParent` as its parent. The virtual member function `Parse()` should be called immediately after this constructor in order to parse the string representation. Unless it is NULL, `aParent` should point to an object of a class derived from `DwField`.

const DwMsgId& operator = (const DwMsgId& aMsgId)

This is the assignment operator, which performs a deep copy of `aMsgId`. The parent node of the `DwMsgId` object is not changed.

virtual void Parse()

This virtual function, inherited from `DwMessageComponent`, executes the parse method for `DwMsgId` objects. The parse method parses the local-part and the domain from the string representation.

You should call this member function after you set or modify the string representation, and before you retrieve local-part or domain.

This function clears the is-modified flag.

virtual void Assemble()

This virtual function, inherited from `DwMessageComponent`, executes the assemble method for `DwMsgId` objects. The assemble method creates or updates the string representation from the local-part and the domain.

You should call this member function after you modify the local-part or the domain, and before you retrieve the string representation.

This function clears the is-modified flag.

virtual DwMessageComponent* Clone() const

This virtual function, inherited from `DwMessageComponent`, creates a new `DwMsgId` on the free store that has the same value as this `DwMsgId` object. The basic idea is that of a ``virtual copy constructor.''

virtual void CreateDefault()

Creates a value for the msg-id. Uses the current time, process id, and fully qualified domain name for the host.

const DwString& LocalPart() const

Returns the local-part of the msg-id.

void SetLocalPart(const DwString& aLocalPart)

Sets the local-part of the msg-id.

const DwString& Domain() const

Returns the domain of the msg-id.

void SetDomain(const DwString& aDomain)

Sets the domain of the msg-id.

static DwMsgId* NewMsgId(const DwString& aStr, DwMessageComponent* aParent)

Creates a new `DwMsgId` object on the free store. If the static data member `sNewMsgId` is NULL, this member function will create a new `DwMsgId` and return it. Otherwise, `NewMsgId()` will call the user-supplied function pointed to by `sNewMsgId`, which is assumed to return an object from a class derived from `DwMsgId`, and return that object.

virtual void PrintDebugInfo(ostream& aStrm, int aDepth=0) const

This virtual function, inherited from `DwMessageComponent`, prints debugging information about this object to `aStrm`. It will also call `PrintDebugInfo()` for any of its child components down to a level of `aDepth`.

This member function is available only in the debug version of the library.

virtual void CheckInvariants() const

Aborts if one of the invariants of the object fails. Use this member function to track down bugs.

This member function is available only in the debug version of the library.

## Public Data Members

static DwMsgId* (*sNewMsgId)(const DwString&, DwMessageComponent*)

If `sNewMsgId` is not NULL, it is assumed to point to a user-supplied function that returns an object from a class derived from `DwMsgId`.

static const char* sHostName

Host name of machine, used to create msg-id string. This data member is ignored if the platform supports a gethostname() function call.