Add ImplPtr and makeImpl

The original (more complex and comprehensive) solution belongs to
https://oliora.github.io/2015/12/29/pimpl-and-rule-of-zero.html - this
commit only provides a small wrapper for non-copyable Private class
implementations common throughout libQuotient. Unlike the original,
default initialisation is made explicit - you have to pass
ZeroImpl<Private>() instead (and I firmly believe it's a good thing:
normally pointers to Private should not remain nullptr). The reason
ZeroImpl<> is not a template variable is quite simple: unique_ptr is
non-copyable and so cannot be initialised from; while a template
function will initialise the value in-place thanks to copy elision.

4 files changed, 6 insertions, 8 deletions

diff --git a/lib/jobs/basejob.cpp b/lib/jobs/basejob.cpp
index 971fea7b..f518a1b0 100644
--- a/lib/jobs/basejob.cpp
+++ b/lib/jobs/basejob.cpp
@@ -194,8 +194,8 @@ BaseJob::BaseJob(HttpVerb verb, const QString& name, QByteArray endpoint,
 
 BaseJob::BaseJob(HttpVerb verb, const QString& name, QByteArray endpoint,
                  const QUrlQuery& query, RequestData&& data, bool needsToken)
-    : d(new Private(verb, std::move(endpoint), query, std::move(data),
-                    needsToken))
+    : d(makeImpl<Private>(verb, std::move(endpoint), query, std::move(data),
+                          needsToken))
 {
     setObjectName(name);
     connect(&d->timer, &QTimer::timeout, this, &BaseJob::timeout);
diff --git a/lib/jobs/basejob.h b/lib/jobs/basejob.h
index f41fc63c..c899170d 100644
--- a/lib/jobs/basejob.h
+++ b/lib/jobs/basejob.h
@@ -467,7 +467,7 @@ private:
     void finishJob();
 
     class Private;
-    QScopedPointer<Private> d;
+    ImplPtr<Private> d;
 };
 
 inline bool QUOTIENT_API isJobPending(BaseJob* job)
diff --git a/lib/jobs/downloadfilejob.cpp b/lib/jobs/downloadfilejob.cpp
index 6bf221cb..4a507ebd 100644
--- a/lib/jobs/downloadfilejob.cpp
+++ b/lib/jobs/downloadfilejob.cpp
@@ -32,13 +32,12 @@ DownloadFileJob::DownloadFileJob(const QString& serverName,
                                  const QString& mediaId,
                                  const QString& localFilename)
     : GetContentJob(serverName, mediaId)
-    , d(localFilename.isEmpty() ? new Private : new Private(localFilename))
+    , d(localFilename.isEmpty() ? makeImpl<Private>()
+                                : makeImpl<Private>(localFilename))
 {
     setObjectName(QStringLiteral("DownloadFileJob"));
 }
 
-DownloadFileJob::~DownloadFileJob() = default;
-
 QString DownloadFileJob::targetFileName() const
 {
     return (d->targetFile ? d->targetFile : d->tempFile)->fileName();
diff --git a/lib/jobs/downloadfilejob.h b/lib/jobs/downloadfilejob.h
index 9e807fe7..f8c62e4b 100644
--- a/lib/jobs/downloadfilejob.h
+++ b/lib/jobs/downloadfilejob.h
@@ -13,13 +13,12 @@ public:
 
     DownloadFileJob(const QString& serverName, const QString& mediaId,
                     const QString& localFilename = {});
-    ~DownloadFileJob() override;
 
     QString targetFileName() const;
 
 private:
     class Private;
-    QScopedPointer<Private> d;
+    ImplPtr<Private> d;
 
     void doPrepare() override;
     void onSentRequest(QNetworkReply* reply) override;