xpcom/sample/nsSample.h

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  37
  38 /**
  39  * A sample of XPConnect. This file is the header of an implementation
  40  * nsSample of the nsISample interface.
  41  *
  42  */
  43
  44 #include "nsISample.h"
  45
  46 /**
  47  * SampleImpl is an implementation of the nsISample interface.  In XPCOM,
  48  * there can be more than one implementation of an given interface.  Class
  49  * IDs (CIDs) uniquely identify a particular implementation of an interface.
  50  * Interface IDs (IIDs) uniquely identify an interface.
  51  *
  52  * The CID is also a unique number that looks just like an IID
  53  * and uniquely identifies an implementation
  54  * {7CB5B7A0-07D7-11d3-BDE2-000064657374}
  55  */
  56
  57 #define NS_SAMPLE_CID \
  58 { 0x7cb5b7a0, 0x7d7, 0x11d3, { 0xbd, 0xe2, 0x0, 0x0, 0x64, 0x65, 0x73, 0x74 } }
  59
  60 #define NS_SAMPLE_CONTRACTID "@mozilla.org/sample;1"
  61
  62
  63 class nsSampleImpl : public nsISample
  64 {
  65 public:
  66     nsSampleImpl();
  67
  68     /**
  69      * This macro expands into a declaration of the nsISupports interface.
  70      * Every XPCOM component needs to implement nsISupports, as it acts
  71      * as the gateway to other interfaces this component implements.  You
  72      * could manually declare QueryInterface, AddRef, and Release instead
  73      * of using this macro, but why?
  74      */
  75     // nsISupports interface
  76     NS_DECL_ISUPPORTS
  77
  78     /**
  79      * This macro is defined in the nsISample.h file, and is generated
  80      * automatically by the xpidl compiler.  It expands to
  81      * declarations of all of the methods required to implement the
  82      * interface.  xpidl will generate a NS_DECL_[INTERFACENAME] macro
  83      * for each interface that it processes.
  84      *
  85      * The methods of nsISample are discussed individually below, but
  86      * commented out (because this macro already defines them.)
  87      */
  88     NS_DECL_NSISAMPLE
  89
  90     /**
  91      * The following is an explanation of how the interface header
  92      * file expands to for a c++ implementation. NS_DELC_NSISAMPLE
  93      * takes care of defining the right c++ implementation.
  94      *
  95      * The following if provided for more understanding.
  96      *
  97      * NS_IMETHOD expands to the standard XPCOM return type.  XPCOM methods
  98      * should never return any other type.  The return value is used
  99      * behind the scenes by the XPConnect runtime to figure out if the call
 100      * failed in any way.
 101      * These methods were generated by "attribute string Value" in
 102      * nsISample.idl.  When reflected into JavaScript, XPCOM will use these
 103      * calls as Getter/Setter ops, so that they can be called transparently
 104      * as "sample.Value='foo';" and "var val = sample.Value"
 105      */
 106     /* NS_IMETHOD GetValue(char * *aValue); */
 107     /* NS_IMETHOD SetValue(char * aValue); */
 108
 109     /**
 110      * The const came from the "in" specifier in nsISample.idl.  "in"
 111      * specifies that the value of this parameter is used only for input,
 112      * this method is not allowed to modify the contents of the buffer.
 113      */
 114     /* NS_IMETHOD WriteValue(const char *aPrefix); */
 115
 116     /**
 117      * nsISample.idl specifies all of it's string types as string, instead
 118      * of wstring (wide string), the Unicode type.  If the world were a
 119      * perfect place, all normal strings in XPCOM interfaces would be unicode.
 120      * If this type had been specified as wstring, it would appear as
 121      * PRUnichar * in C++, which is the NSPR type for unicode characters.
 122      */
 123     /* NS_IMETHOD Poke(const char* aValue); */
 124
 125 private:
 126     ~nsSampleImpl();
 127
 128     char* mValue;
 129 };