sigc::signal_base Struct Reference
Signals

Base class for the sigc::signal# templates. More...

`#include <sigc++/signal_base.h>`

Inheritance diagram for sigc::signal_base:
[legend]

## Public Types

typedef std::size_t | size_type
Public Types inherited from sigc::trackable
typedef internal::func_destroy_notify | func_destroy_notify

## Public Member Functions

| signal_base () noexcept
| signal_base (const signal_base& src) noexcept
| signal_base (signal_base&& src)
| ~signal_base ()
void | block (bool should_block=true) noexcept
| Sets the blocking state of all slots in the list. More...
bool | blocked () const noexcept
| Returns whether all slots in the list are blocked. More...
void | clear ()
| Empties the list of slots. More...
bool | empty () const noexcept
| Returns whether the list of slots is empty. More...
signal_base& | operator= (const signal_base& src)
signal_base& | operator= (signal_base&& src)
size_type | size () const noexcept
| Returns the number of slots in the list. More...
void | unblock () noexcept
| Unsets the blocking state of all slots in the list. More...
Public Member Functions inherited from sigc::trackable
| trackable () noexcept
| trackable (const trackable& src) noexcept
| trackable (trackable&& src)
| ~trackable ()
void | add_destroy_notify_callback (void* data, func_destroy_notify func) const
| Add a callback that is executed (notified) when the trackable object is detroyed. More...
void | notify_callbacks ()
| Execute and remove all previously installed callbacks. More...
trackable& | operator= (const trackable& src)
trackable& | operator= (trackable&& src)
void | remove_destroy_notify_callback (void* data) const
| Remove a callback previously installed with add_destroy_notify_callback(). More...

## Protected Types

typedef internal::signal_impl::iterator_type | iterator_type

## Protected Member Functions

iterator_type | connect (const slot_base& slot_)
| Adds a slot at the end of the list of slots. More...
iterator_type | connect (slot_base&& slot_)
| Adds a slot at the end of the list of slots. More...
iterator_type | erase (iterator_type i)
| Removes the slot at the given position from the list of slots. More...
internal::signal_impl* | impl () const
| Returns the signal_impl object encapsulating the list of slots. More...
iterator_type | insert (iterator_type i, const slot_base& slot_)
| Adds a slot at the given position into the list of slots. More...
iterator_type | insert (iterator_type i, slot_base&& slot_)
| Adds a slot at the given position into the list of slots. More...

## Protected Attributes

internal::signal_impl* | impl_
| The signal_impl object encapsulating the slot list. More...

## Detailed Description

Base class for the sigc::signal# templates.

signal_base integrates most of the interface of the derived sigc::signal# templates. The implementation, however, resides in sigc::internal::signal_impl. A sigc::internal::signal_impl object is dynamically allocated from signal_base when first connecting a slot to the signal. This ensures that empty signals don't waste memory.

sigc::internal::signal_impl is reference-counted. When a sigc::signal# object is copied, the reference count of its sigc::internal::signal_impl object is incremented. Both sigc::signal# objects then refer to the same sigc::internal::signal_impl object.

Deleting the signal during emission, e.g. from one of its slots, may result in memory leaks. This drawback is fixed in version 3 of libsigc++. A workaround is to make a copy of the signal during the emission:

sigc::signal<...> sig2(*p_sig);
p_sig->emit();

This is not very costly. A sigc::signal<> is not much more than a pointer to a sigc::internal::signal_impl instance, which is not copied.

## Member Typedef Documentation

typedef internal::signal_impl::iterator_type sigc::signal_base::iterator_type

protected

typedef std::size_t sigc::signal_base::size_type

## Constructor & Destructor Documentation

sigc::signal_base::signal_base | ( |  | ) |

noexcept

sigc::signal_base::signal_base | ( | const signal_base& | src | ) |

noexcept

sigc::signal_base::signal_base | ( | signal_base&& | src | ) |

sigc::signal_base::~signal_base | ( |  | ) |

## Member Function Documentation

void sigc::signal_base::block | ( | bool | should_block = `true` | ) |

noexcept

Sets the blocking state of all slots in the list.

If should_block is `true` then the blocking state is set. Subsequent emissions of the signal don't invoke the functors contained in the slots until unblock() or block() with should_block = `false` is called. sigc::slot_base::block() and sigc::slot_base::unblock() can change the blocking state of individual slots.

Parameters

  should_block | Indicates whether the blocking state should be set or unset.

Since libsigc++ 2.4:

bool sigc::signal_base::blocked | ( |  | ) | const

noexcept

Returns whether all slots in the list are blocked.

Returns
  `true` if all slots are blocked or the list is empty.

Since libsigc++ 2.4:

void sigc::signal_base::clear | ( |  | ) |

Empties the list of slots.

iterator_type sigc::signal_base::connect | ( | const slot_base& | slot_ | ) |

protected

Adds a slot at the end of the list of slots.

With connect(), slots can also be added during signal emission. In this case, they won't be executed until the next emission occurs.

Parameters

  slot_ | The slot to add to the list of slots.

Returns
  An iterator pointing to the new slot in the list.

iterator_type sigc::signal_base::connect | ( | slot_base&& | slot_ | ) |

protected

Adds a slot at the end of the list of slots.

With connect(), slots can also be added during signal emission. In this case, they won't be executed until the next emission occurs.

Parameters

  slot_ | The slot to add to the list of slots.

Returns
  An iterator pointing to the new slot in the list.

Since libsigc++ 2.8:

bool sigc::signal_base::empty | ( |  | ) | const

inline noexcept

Returns whether the list of slots is empty.

Returns
  `true` if the list of slots is empty.

iterator_type sigc::signal_base::erase | ( | iterator_type | i | ) |

protected

Removes the slot at the given position from the list of slots.

Note that this function does not work during signal emission!

Parameters

  i | An iterator pointing to the slot to be removed.

Returns
  An iterator pointing to the slot in the list after the one removed.

internal::signal_impl* sigc::signal_base::impl | ( |  | ) | const

protected

Returns the signal_impl object encapsulating the list of slots.

Returns
  The signal_impl object encapsulating the list of slots.

iterator_type sigc::signal_base::insert | ( | iterator_type | i,
|  | const slot_base& | slot_
| ) |  |

protected

Adds a slot at the given position into the list of slots.

Note that this function does not work during signal emission!

Parameters

  i | An iterator indicating the position where slot_ should be inserted.
  slot_ | The slot to add to the list of slots.

Returns
  An iterator pointing to the new slot in the list.

iterator_type sigc::signal_base::insert | ( | iterator_type | i,
|  | slot_base&& | slot_
| ) |  |

protected

Adds a slot at the given position into the list of slots.

Note that this function does not work during signal emission!

Parameters

  i | An iterator indicating the position where slot_ should be inserted.
  slot_ | The slot to add to the list of slots.

Returns
  An iterator pointing to the new slot in the list.

Since libsigc++ 2.8:

signal_base& sigc::signal_base::operator= | ( | const signal_base& | src | ) |

signal_base& sigc::signal_base::operator= | ( | signal_base&& | src | ) |

size_type sigc::signal_base::size | ( |  | ) | const

noexcept

Returns the number of slots in the list.

Returns
  The number of slots in the list.

void sigc::signal_base::unblock | ( |  | ) |

noexcept

Unsets the blocking state of all slots in the list.

Since libsigc++ 2.4:

## Member Data Documentation

internal::signal_impl* sigc::signal_base::impl_

mutable protected

The signal_impl object encapsulating the slot list.