NAME

DwParameter -- Class representing a MIME field body parameter

SYNOPSIS

class DW_EXPORT DwParameter : public DwMessageComponent {

    friend class DwMediaType;

public:

    DwParameter();
    DwParameter(const DwParameter& aParam);
    DwParameter(const DwString& aStr, DwMessageComponent* aParent=0);
    virtual ~DwParameter();
    const DwParameter& operator = (const DwParameter& aParam);
    virtual void Parse();
    virtual void Assemble();
    virtual DwMessageComponent* Clone() const;
    const DwString& Attribute() const;
    void SetAttribute(const DwString& aAttribute);
    const DwString& Value() const;
    void SetValue(const DwString& aValue);
    DwParameter* Next() const ;
    void SetNext(DwParameter* aParam);
    static DwParameter* NewParameter(const DwString& aStr,
        DwMessageComponent* aParent);
    static DwParameter* (*sNewParameter)(const DwString&, DwMessageComponent*);

public:

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

protected:

    void _PrintDebugInfo(ostream& aStrm) const;
};

DESCRIPTION

DwParameter represents the parameter component of the Content-Type header field as described in RFC-2045. A parameter consists of an attribute/value pair. DwParameter has member functions for getting or setting a parameter's attribute and value.

A DwParameter object may be included in a list of DwParameter objects. You can get the next DwParameter object in the list by calling the member function Next().

Public Member Functions

DwParameter()
DwParameter(const DwParameter& aParam)
DwParameter(const DwString& aStr, DwMessageComponent* aParent=0)

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

The second constructor is the copy constructor, which copies the string representation, attribute, and value from aParam. The tqparent of the new DwParameter object is set to NULL.

The third constructor copies aStr to the DwParameter object's string representation and sets aParent as its tqparent. 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 DwMediaType.

const DwParameter& operator = (const DwParameter& aParam)

This is the assignment operator.

virtual void Parse()

This virtual function, inherited from DwMessageComponent, executes the parse method for DwParameter objects. It should be called immediately after the string representation is modified and before the parts of the broken-down representation are accessed.

virtual void Assemble()

This virtual function, inherited from DwMessageComponent, executes the assemble method for DwParameter objects. It should be called whenever one of the object's attributes is changed in order to assemble the string representation from its broken-down representation. It will be called automatically for this object by the tqparent object's Assemble() member function if the is-modified flag is set.

virtual DwMessageComponent* Clone() const

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

const DwString& Attribute() const

Returns the attribute contained by this parameter.

void SetAttribute(const DwString& aAttribute)

Sets the attribute contained by this parameter.

const DwString& Value() const

Returns the value contained by this parameter.

void SetValue(const DwString& aValue)

Sets the value contained by this parameter.

DwParameter* Next() const

Returns the next DwParameter object in the list.

void SetNext(DwParameter* aParam)

Returns the next DwParameter object in the list. Since DwMediaType has member functions for adding DwParameter objects to its list, you should avoid using this function.

static DwParameter* NewParameter(const DwString& aStr, DwMessageComponent* aParent)

Creates a new DwParameter object on the free store. If the static data member sNewParameter is NULL, this member function will create a new DwParameter and return it. Otherwise, NewParameter() will call the user-supplied function pointed to by sNewParameter, which is assumed to return an object from a class derived from DwParameter, 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 DwParameter* (*sNewParameter)(const DwString&, DwMessageComponent*)

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