Difference between revisions of "Foobar2000:Development:Auto Pointers"
(Created page with "Category:Foobar2000 Development When performing most kinds of service operations, <code>service_ptr_t<T></code> template should be used instead of working with service po...") |
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service_ptr_t<> provides additional convenience operators: | service_ptr_t<> provides additional convenience operators: | ||
* <code>operator&=</code> | * <code>operator&=</code> | ||
| − | Attempts to obtain a pointer to another interface, if the passed object supports it. Returns true on success, false on failure. | + | Attempts to obtain a pointer to another interface, if the passed object supports it. Returns true on success, false on failure - interface not implemented or null pointer. |
<pre> | <pre> | ||
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A = create_service1(); | A = create_service1(); | ||
if ( B &= A ) { | if ( B &= A ) { | ||
| − | // | + | // B is valid. |
| + | // Do stuff with B. | ||
} else { | } else { | ||
| − | // A does not implement service2, or is null | + | // A does not implement service2, or is null. |
} | } | ||
</pre> | </pre> | ||
Latest revision as of 20:12, 21 June 2022
When performing most kinds of service operations, service_ptr_t<T> template should be used instead of working with service pointers directly; it automatically manages reference counting, ensuring that the service object is deleted when it is no longer referenced.
For convenience, all service classes have myclass::ptr typedef'd to service_ptr_t<myclass>.
When working with pointers to core fb2k services, just use C++11 auto keyword and someclass::get(), e.g. auto myAPI = playlist_manager::get();
service_ptr_t<> provides additional convenience operators:
-
operator&=
Attempts to obtain a pointer to another interface, if the passed object supports it. Returns true on success, false on failure - interface not implemented or null pointer.
service_ptr_t<service1> A;
service_ptr_t<service2> B;
A = create_service1();
if ( B &= A ) {
// B is valid.
// Do stuff with B.
} else {
// A does not implement service2, or is null.
}
-
operator^=
Forced cast. Use to obtain a valid pointer to another interface in a scenario where you know that the object supports it.
There's no error return, the process crashes if the interface you ask for is not implemented by this object.
service_ptr_t<service1> A; service_ptr_t<service2> B; A = create_service1(); B ^= A; // if you get here, B is valid (or null if A was null)
Use the above operators to safely cast from parent service class to derived service class. Do not use C++ dynamic_cast<> / static_cast<> / reinterpret_cast<> on foobar2000 service classes.
