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.

1 files changed, 2 insertions, 3 deletions

diff --git a/lib/user.h b/lib/user.h
index 435304ce..8412b7fd 100644
--- a/lib/user.h
+++ b/lib/user.h
@@ -5,7 +5,7 @@
 #pragma once
 
 #include "avatar.h"
-#include "quotient_export.h"
+#include "util.h"
 
 #include <QtCore/QObject>
 
@@ -27,7 +27,6 @@ class QUOTIENT_API User : public QObject {
     Q_PROPERTY(QUrl avatarUrl READ avatarUrl NOTIFY defaultAvatarChanged)
 public:
     User(QString userId, Connection* connection);
-    ~User() override;
 
     Connection* connection() const;
 
@@ -126,7 +125,7 @@ Q_SIGNALS:
 
 private:
     class Private;
-    QScopedPointer<Private> d;
+    ImplPtr<Private> d;
 
     template <typename SourceT>
     bool doSetAvatar(SourceT&& source);