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author | fischman@chromium.org <fischman@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98> | 2012-03-24 20:37:27 +0000 |
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committer | fischman@chromium.org <fischman@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98> | 2012-03-24 20:37:27 +0000 |
commit | 1192339cc77909d203a40ce01919f55fec39413f (patch) | |
tree | d89480c7fea632c896a70e41542785511830407b /base/callback_helpers.h | |
parent | 6e04d17161b8d53770979fb5a451da8174e255c6 (diff) | |
download | chromium_src-1192339cc77909d203a40ce01919f55fec39413f.zip chromium_src-1192339cc77909d203a40ce01919f55fec39413f.tar.gz chromium_src-1192339cc77909d203a40ce01919f55fec39413f.tar.bz2 |
Make Callback::Reset() return a copy to support use-cases where Run() ends up modifying |*this|. Callers can use
cb.Reset().Run(args...);
to avoid reentrancy-like bugs.
Replace the special-purpose versions of ResetAndRunCB in the media/ codebase
with this more-general facility.
Review URL: http://codereview.chromium.org/9717021
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@128772 0039d316-1c4b-4281-b951-d872f2087c98
Diffstat (limited to 'base/callback_helpers.h')
-rw-r--r-- | base/callback_helpers.h | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/base/callback_helpers.h b/base/callback_helpers.h new file mode 100644 index 0000000..52cb71b --- /dev/null +++ b/base/callback_helpers.h @@ -0,0 +1,30 @@ +// Copyright (c) 2012 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. + +// This defines helpful methods for dealing with Callbacks. Because Callbacks +// are implemented using templates, with a class per callback signature, adding +// methods to Callback<> itself is unattractive (lots of extra code gets +// generated). Instead, consider adding methods here. +// +// ResetAndReturn(&cb) is like cb.Reset() but allows executing a callback (via a +// copy) after the original callback is Reset(). This can be handy if Run() +// reads/writes the variable holding the Callback. + +#ifndef BASE_CALLBACK_HELPERS_H_ +#define BASE_CALLBACK_HELPERS_H_ + +#include "base/callback.h" + +namespace base { + +template <typename Sig> +base::Callback<Sig> ResetAndReturn(base::Callback<Sig>* cb) { + base::Callback<Sig> ret(*cb); + cb->Reset(); + return ret; +} + +} // namespace base + +#endif // BASE_CALLBACK_HELPERS_H_ |