0
Files
src/base/bind_helpers.h
kylechar 650caf0ede base: Cleanup callback types (part 6).
Remove some usage of deprecated callback types in base/*. Where possible
convert to the corresponding once type, otherwise replace with the
repeating type.

Bug: 714018
Change-Id: I769373b6bb9c4ae3331faf71e8a666bff6f0611f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1690929
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: kylechar <kylechar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#678111}
2019-07-17 03:25:41 +00:00

70 lines
1.8 KiB
C++

// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_BIND_HELPERS_H_
#define BASE_BIND_HELPERS_H_
#include <stddef.h>
#include <type_traits>
#include <utility>
#include "base/bind.h"
#include "base/callback.h"
#include "base/memory/weak_ptr.h"
#include "build/build_config.h"
// This defines a set of simple functions and utilities that people want when
// using {Once,Repeating}Callback<> and Bind{Once,Repeating}().
namespace base {
// Creates a null callback.
class BASE_EXPORT NullCallback {
public:
template <typename R, typename... Args>
operator RepeatingCallback<R(Args...)>() const {
return RepeatingCallback<R(Args...)>();
}
template <typename R, typename... Args>
operator OnceCallback<R(Args...)>() const {
return OnceCallback<R(Args...)>();
}
};
// Creates a callback that does nothing when called.
class BASE_EXPORT DoNothing {
public:
template <typename... Args>
operator RepeatingCallback<void(Args...)>() const {
return Repeatedly<Args...>();
}
template <typename... Args>
operator OnceCallback<void(Args...)>() const {
return Once<Args...>();
}
// Explicit way of specifying a specific callback type when the compiler can't
// deduce it.
template <typename... Args>
static RepeatingCallback<void(Args...)> Repeatedly() {
return BindRepeating([](Args... args) {});
}
template <typename... Args>
static OnceCallback<void(Args...)> Once() {
return BindOnce([](Args... args) {});
}
};
// Useful for creating a Closure that will delete a pointer when invoked. Only
// use this when necessary. In most cases MessageLoop::DeleteSoon() is a better
// fit.
template <typename T>
void DeletePointer(T* obj) {
delete obj;
}
} // namespace base
#endif // BASE_BIND_HELPERS_H_