lsignal: C++ signal/slot system.
lsignal (or lightweight signal) is a very little and fast C++ thread-safe implementation of signal and slot system which is based on modern C++11 code.
Requirements
C++ compiler with support C++11.
How to use
Include lsignal.h in your project.
Essential classes
signal
This is a template class which holds callbacks and can emit signals with certain arguments. See examples of declarations:
| Declaration | Description |
|---|---|
lsignal::signal<void()> s; |
Signal without parameters, return type - void |
lsignal::signal<int(int,int)> t; |
Signal with two parameters, return type - int |
lsignal::signal<std::string()> u; |
Signal without parameters, return type - std::string |
You can connect to signal any callback which looks like callable object but be aware than signature of callback must be equal signature of corresponding signal:
| Callback | Description |
|---|---|
s.connect(foo); |
foo is a common function |
s.connect(bar); |
bar is a lambda function |
s.connect(baz); |
baz is a class with operator() |
s.connect(&qx, &qux::func); |
qx is a instance of class qux |
Result of this function is a instance of class connection.
When signal is emitted return value will be the result of executing last connected callback. If you want to receive all results of callbacks you should pass aggregate function as last parameter:
lsignal::signal<int(int,int)> s;
...
auto agg = [](const std::vector<int>& v) -> int { ... };
s(2, 3, agg);connection
connection contains link between signal and callback. Available next operations:
| Method | Description |
|---|---|
is_locked |
Check if connection is locked |
set_lock |
If connection is locked then callback won't be called |
disconnect |
Remove callback from signal |
Also you can pass connection directly to signal::disconnect for disconnecting this connection.
slot
This class similar to connection but is used for owhership policy. Look example:
class foo : public lsignal::slot
{
...
};
...
foo f;
// disconnect when f was destroyed
s.connect([](){ ... }, &f);Performance
Synthetic test (one or more empty callbacks) showed that calling lsignal from two
to five times faster than calling boost::signal2 which was created with dummy (empty) mutex.