pybind11

1561 Commits

30 Branches

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70 MiB

Branch: array-sequence-fix

Commit Graph

Author	SHA1	Message	Date
Dean Moldovan	39fd6a9463	Reduce binary size overhead of new-style constructors The lookup of the `self` type and value pointer are moved out of template code and into `dispatcher`. This brings down the binary size of constructors back to the level of the old placement-new approach. (It also avoids a second lookup for `init_instance`.) With this implementation, mixing old- and new-style constructors in the same overload set may result in some runtime overhead for temporary allocations/deallocations, but this should be fine as old style constructors are phased out.	8 years ago
Jason Rhinelander	c4e180081d	Reimplement py::init<...> to use common factory code This reimplements the py::init<...> implementations using the various functions added to support `py::init(...)`, and moves the implementing structs into `detail/init.h` from `pybind11.h`. It doesn't simply use a factory directly, as this is a very common case and implementation without an extra lambda call is a small but useful optimization. This, combined with the previous lazy initialization, also avoids needing placement new for `py::init<...>()` construction: such construction now occurs via an ordinary `new Type(...)`. A consequence of this is that it also fixes a potential bug when using multiple inheritance from Python: it was very easy to write classes that double-initialize an existing instance which had the potential to leak for non-pod classes. With the new implementation, an attempt to call `__init__` on an already-initialized object is now ignored. (This was already done in the previous commit for factory constructors). This change exposed a few warnings (fixed here) from deleting a pointer to a base class with virtual functions but without a virtual destructor. These look like legitimate warnings that we shouldn't suppress; this adds virtual destructors to the appropriate classes.	8 years ago
Jason Rhinelander	464d98962d	Allow binding factory functions as constructors This allows you to use: cls.def(py::init(&factory_function)); where `factory_function` returns a pointer, holder, or value of the class type (or a derived type). Various compile-time checks (static_asserts) are performed to ensure the function is valid, and various run-time type checks where necessary. Some other details of this feature: - The `py::init` name doesn't conflict with the templated no-argument `py::init<...>()`, but keeps the naming consistent: the existing templated, no-argument one wraps constructors, the no-template, function-argument one wraps factory functions. - If returning a CppClass (whether by value or pointer) when an CppAlias is required (i.e. python-side inheritance and a declared alias), a dynamic_cast to the alias is attempted (for the pointer version); if it fails, or if returned by value, an Alias(Class &&) constructor is invoked. If this constructor doesn't exist, a runtime error occurs. - for holder returns when an alias is required, we try a dynamic_cast of the wrapped pointer to the alias to see if it is already an alias instance; if it isn't, we raise an error. - `py::init(class_factory, alias_factory)` is also available that takes two factories: the first is called when an alias is not needed, the second when it is. - Reimplement factory instance clearing. The previous implementation failed under python-side multiple inheritance: each inherited type's factory init would clear the instance instead of only setting its own type value. The new implementation here clears just the relevant value pointer. - dealloc is updated to explicitly set the leftover value pointer to nullptr and the `holder_constructed` flag to false so that it can be used to clear preallocated value without needing to rebuild the instance internals data. - Added various tests to test out new allocation/deallocation code. - With preallocation now done lazily, init factory holders can completely avoid the extra overhead of needing an extra allocation/deallocation. - Updated documentation to make factory constructors the default advanced constructor style. - If an `__init__` is called a second time, we have two choices: we can throw away the first instance, replacing it with the second; or we can ignore the second call. The latter is slightly easier, so do that.	8 years ago

Author

SHA1

Message

Date

Dean Moldovan

39fd6a9463

Reduce binary size overhead of new-style constructors

The lookup of the `self` type and value pointer are moved out of
template code and into `dispatcher`. This brings down the binary
size of constructors back to the level of the old placement-new
approach. (It also avoids a second lookup for `init_instance`.)

With this implementation, mixing old- and new-style constructors
in the same overload set may result in some runtime overhead for
temporary allocations/deallocations, but this should be fine as
old style constructors are phased out.

8 years ago

Jason Rhinelander

c4e180081d

Reimplement py::init<...> to use common factory code

This reimplements the py::init<...> implementations using the various
functions added to support `py::init(...)`, and moves the implementing
structs into `detail/init.h` from `pybind11.h`.  It doesn't simply use a
factory directly, as this is a very common case and implementation
without an extra lambda call is a small but useful optimization.

This, combined with the previous lazy initialization, also avoids
needing placement new for `py::init<...>()` construction: such
construction now occurs via an ordinary `new Type(...)`.

A consequence of this is that it also fixes a potential bug when using
multiple inheritance from Python: it was very easy to write classes
that double-initialize an existing instance which had the potential to
leak for non-pod classes.  With the new implementation, an attempt to
call `__init__` on an already-initialized object is now ignored.  (This
was already done in the previous commit for factory constructors).

This change exposed a few warnings (fixed here) from deleting a pointer
to a base class with virtual functions but without a virtual destructor.
These look like legitimate warnings that we shouldn't suppress; this
adds virtual destructors to the appropriate classes.

8 years ago

Jason Rhinelander

464d98962d

Allow binding factory functions as constructors

This allows you to use:

    cls.def(py::init(&factory_function));

where `factory_function` returns a pointer, holder, or value of the
class type (or a derived type).  Various compile-time checks
(static_asserts) are performed to ensure the function is valid, and
various run-time type checks where necessary.

Some other details of this feature:
- The `py::init` name doesn't conflict with the templated no-argument
  `py::init<...>()`, but keeps the naming consistent: the existing
  templated, no-argument one wraps constructors, the no-template,
  function-argument one wraps factory functions.
- If returning a CppClass (whether by value or pointer) when an CppAlias
  is required (i.e. python-side inheritance and a declared alias), a
  dynamic_cast to the alias is attempted (for the pointer version); if
  it fails, or if returned by value, an Alias(Class &&) constructor
  is invoked.  If this constructor doesn't exist, a runtime error occurs.
- for holder returns when an alias is required, we try a dynamic_cast of
  the wrapped pointer to the alias to see if it is already an alias
  instance; if it isn't, we raise an error.
- `py::init(class_factory, alias_factory)` is also available that takes
  two factories: the first is called when an alias is not needed, the
  second when it is.
- Reimplement factory instance clearing.  The previous implementation
  failed under python-side multiple inheritance: *each* inherited
  type's factory init would clear the instance instead of only setting
  its own type value.  The new implementation here clears just the
  relevant value pointer.
- dealloc is updated to explicitly set the leftover value pointer to
  nullptr and the `holder_constructed` flag to false so that it can be
  used to clear preallocated value without needing to rebuild the
  instance internals data.
- Added various tests to test out new allocation/deallocation code.
- With preallocation now done lazily, init factory holders can
  completely avoid the extra overhead of needing an extra
  allocation/deallocation.
- Updated documentation to make factory constructors the default
  advanced constructor style.
- If an `__init__` is called a second time, we have two choices: we can
  throw away the first instance, replacing it with the second; or we can
  ignore the second call.  The latter is slightly easier, so do that.

8 years ago

3 Commits (array-sequence-fix)