qBittorrent
settingvalue.h
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1 /*
2  * Bittorrent Client using Qt and libtorrent.
3  * Copyright (C) 2016 Vladimir Golovnev <glassez@yandex.ru>
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU General Public License
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10  * This program is distributed in the hope that it will be useful,
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27  */
28 
29 #pragma once
30 
31 #include <QString>
32 
33 #include "settingsstorage.h"
34 
35 // This is a thin/handy wrapper over `SettingsStorage`. Use it when store/load value
36 // rarely occurs, otherwise use `CachedSettingValue`.
37 template <typename T>
39 {
40 public:
41  explicit SettingValue(const char *keyName)
42  : m_keyName {QLatin1String {keyName}}
43  {
44  }
45 
46  T get(const T &defaultValue = {}) const
47  {
48  return SettingsStorage::instance()->loadValue(m_keyName, defaultValue);
49  }
50 
51  operator T() const
52  {
53  return get();
54  }
55 
57  {
59  return *this;
60  }
61 
62 private:
63  const QString m_keyName;
64 };
65 
66 template <typename T>
68 {
69 public:
70  explicit CachedSettingValue(const char *keyName, const T &defaultValue = {})
71  : m_setting {keyName}
72  , m_cache {m_setting.get(defaultValue)}
73  {
74  }
75 
76  // The signature of the ProxyFunc should be equivalent to the following:
77  // T proxyFunc(const T &a);
78  template <typename ProxyFunc>
79  explicit CachedSettingValue(const char *keyName, const T &defaultValue, ProxyFunc &&proxyFunc)
80  : m_setting {keyName}
81  , m_cache {proxyFunc(m_setting.get(defaultValue))}
82  {
83  }
84 
85  T get() const
86  {
87  return m_cache;
88  }
89 
90  operator T() const
91  {
92  return get();
93  }
94 
96  {
97  if (m_cache == value)
98  return *this;
99 
100  m_setting = value;
101  m_cache = value;
102  return *this;
103  }
104 
105 private:
108 };
CachedSettingValue(const char *keyName, const T &defaultValue, ProxyFunc &&proxyFunc)
Definition: settingvalue.h:79
CachedSettingValue< T > & operator=(const T &value)
Definition: settingvalue.h:95
SettingValue< T > m_setting
Definition: settingvalue.h:106
CachedSettingValue(const char *keyName, const T &defaultValue={})
Definition: settingvalue.h:70
T get(const T &defaultValue={}) const
Definition: settingvalue.h:46
SettingValue< T > & operator=(const T &value)
Definition: settingvalue.h:56
const QString m_keyName
Definition: settingvalue.h:63
SettingValue(const char *keyName)
Definition: settingvalue.h:41
void storeValue(const QString &key, const T &value)
T loadValue(const QString &key, const T &defaultValue={}) const
static SettingsStorage * instance()
T value(const QString &key, const T &defaultValue={})
Definition: preferences.cpp:64