Turn advertiser callbacks into lambdas

README.md

@@ -53,16 +53,11 @@ This library uses the Bonjour SDK and expects it to be in the default install lo
 
     #include <dnssd/Advertiser.h>
 
-    class MyAdvertiser : public dnssd::Advertiser
+    dnssd::Advertiser advertiser;
+    advertiser.onAdvertiserErrorAsync ([] (const dnssd::Result& error) 
     {
-    public:
-        void onAdvertiserErrorAsync (const dnssd::Result& error) override
-        {
-            std::cout << "Result: " << error.description() << std::endl;
-        }
-    };
-
-    MyAdvertiser advertiser;
+        std::cout << "Error: " << error.description() << std::endl;
+    });
 
     dnssd::TxtRecord txtRecord = {{"key1", "value1"}, {"key2", "value2"}};
 

examples/dnssd-advertiser.cpp

@@ -4,15 +4,6 @@
 #include <string>
 #include <vector>
 
-class MyAdvertiser : public dnssd::Advertiser
-{
-public:
-    void onAdvertiserErrorAsync (const dnssd::Result& error) override
-    {
-        std::cout << "Error: " << error.description() << std::endl;
-    }
-};
-
 bool parseTxtRecord (dnssd::TxtRecord& txtRecord, const std::string& stringValue)
 {
     if (stringValue.empty())
@@ -28,7 +19,7 @@ bool parseTxtRecord (dnssd::TxtRecord& txtRecord, const std::string& stringValue
     return true;
 }
 
-int main (int argc, char* argv[])
+int main (int const argc, char* argv[])
 {
     std::vector<std::string> args;
     for (int i = 1; i < argc; i++)
@@ -64,7 +55,11 @@ int main (int argc, char* argv[])
         parseTxtRecord (txtRecord, *it);
     }
 
-    MyAdvertiser advertiser;
+    dnssd::Advertiser advertiser;
+
+    advertiser.onAdvertiserErrorAsync ([] (const dnssd::Result& error) {
+        std::cout << "Error: " << error.description() << std::endl;
+    });
 
     auto result = advertiser.registerService (args[0], "001122334455@SomeName", nullptr, portNumber, txtRecord);
     if (result.hasError())
@@ -97,4 +92,6 @@ int main (int argc, char* argv[])
     }
 
     std::cout << "Exit" << std::endl;
+
+    return 0;
 }

include/dnssd/bonjour/BonjourAdvertiser.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include "../common/IAdvertiser.h"
+#include "../common/AdvertiserBase.h"
 #include "../common/Result.h"
 #include "ScopedDnsServiceRef.h"
 
@@ -13,7 +13,7 @@ namespace dnssd
 /**
  * Apple Bonjour implementation of IAdvertiser. Works on macOS and Windows.
  */
-class BonjourAdvertiser : public IAdvertiser
+class BonjourAdvertiser : public AdvertiserBase
 {
 public:
     explicit BonjourAdvertiser() = default;
@@ -31,6 +31,15 @@ class BonjourAdvertiser : public IAdvertiser
 
 private:
     ScopedDnsServiceRef mServiceRef;
+
+    static void DNSSD_API registerServiceCallBack (
+        DNSServiceRef serviceRef,
+        DNSServiceFlags flags,
+        DNSServiceErrorType errorCode,
+        const char* serviceName,
+        const char* regType,
+        const char* replyDomain,
+        void* context);
 };
 
 } // namespace dnssd

include/dnssd/common/IAdvertiser.h → include/dnssd/common/AdvertiserBase.h

@@ -1,22 +1,24 @@
 #pragma once
 
+#include <utility>
+
 #include "../common/TxtRecord.h"
 #include "Result.h"
 #include "Util.h"
 
-#include <functional>
-
 namespace dnssd
 {
 
 /**
  * Interface class which represents a dnssd advertiser object, which is able to present itself onto the network.
  */
-class IAdvertiser
+class AdvertiserBase
 {
 public:
-    explicit IAdvertiser() = default;
-    virtual ~IAdvertiser() = default;
+    using AdvertiserErrorCallback = std::function<void (const Result& error)>;
+
+    explicit AdvertiserBase() = default;
+    virtual ~AdvertiserBase() = default;
 
     /**
      * Registers a service with given arguments.
@@ -53,11 +55,17 @@ class IAdvertiser
     virtual void unregisterService() noexcept = 0;
 
     /**
-     * Called when there was an error.
+     * Set a callback for when an error happens.
      * Note: this call will be made from a background thread and wil not be synchronised.
-     * @param error The error which occured.
+     * @param callback The function to be called when an error happens.
      */
-    virtual void onAdvertiserErrorAsync (const Result& error) { ignore (error); }
+    virtual void onAdvertiserErrorAsync (AdvertiserErrorCallback callback)
+    {
+        onAdvertiserErrorCallback = std::move (callback);
+    }
+
+protected:
+    AdvertiserErrorCallback onAdvertiserErrorCallback;
 };
 
 } // namespace dnssd

src/bonjour/BonjourAdvertiser.cpp

@@ -4,32 +4,6 @@
 #include <iostream>
 #include <thread>
 
-static void DNSSD_API registerServiceCallBack (
-    DNSServiceRef serviceRef,
-    DNSServiceFlags flags,
-    DNSServiceErrorType errorCode,
-    const char* serviceName,
-    const char* regType,
-    const char* replyDomain,
-    void* context)
-{
-    (void)serviceRef;
-    (void)flags;
-    (void)serviceName;
-    (void)regType;
-    (void)replyDomain;
-
-    dnssd::Result result (errorCode);
-
-    if (result.hasError())
-    {
-        auto* owner = static_cast<dnssd::BonjourAdvertiser*> (context);
-        owner->onAdvertiserErrorAsync (result);
-        owner->unregisterService();
-        return;
-    }
-}
-
 dnssd::Result dnssd::BonjourAdvertiser::registerService (
     const std::string& regType,
     const char* name,
@@ -67,9 +41,35 @@ void dnssd::BonjourAdvertiser::unregisterService() noexcept
     mServiceRef = nullptr;
 }
 
-dnssd::Result dnssd::BonjourAdvertiser::updateTxtRecord (const dnssd::TxtRecord& txtRecord)
+void dnssd::BonjourAdvertiser::registerServiceCallBack (
+    DNSServiceRef serviceRef,
+    DNSServiceFlags flags,
+    DNSServiceErrorType errorCode,
+    const char* serviceName,
+    const char* regType,
+    const char* replyDomain,
+    void* context)
 {
-    auto record = BonjourTxtRecord (txtRecord);
+    (void)serviceRef;
+    (void)flags;
+    (void)serviceName;
+    (void)regType;
+    (void)replyDomain;
+
+    Result const result (errorCode);
+
+    if (result.hasError())
+    {
+        auto* owner = static_cast<BonjourAdvertiser*> (context);
+        if (owner->onAdvertiserErrorCallback)
+            owner->onAdvertiserErrorCallback (result);
+        owner->unregisterService();
+    }
+}
+
+dnssd::Result dnssd::BonjourAdvertiser::updateTxtRecord (const TxtRecord& txtRecord)
+{
+    auto const record = BonjourTxtRecord (txtRecord);
 
     // Second argument's nullptr tells us that we are updating the primary record.
     return Result (