Rule of Zero PIMPL
A single-header C++ library for PIMPLs without having to implement any special member functions as described in oliora's blog.
Code Samples
Header File:
#include "spimpl.h"
class Copyable {
public:
Copyable(int x);
int x();
// All five special members are compiler-generated.
private:
class Impl;
// Movable and copyable Smart PIMPL
spimpl::impl_ptr<Impl> impl_;
};Implementation File:
Copyable::Copyable(int x)
: impl_(spimpl::make_impl<Impl>(x)) {}
struct Copyable::Impl {
Impl(int x): x(x) {}
int x;
};
int Copyable::x() {
return impl_->x;
}GDB Support
For easier debugging with GDB you might want to add the following to your
.gdbinit file. This makes *impl_ and impl-> behave more naturally in
GDB.
python
import gdb
import gdb.xmethod
import libstdcxx.v6.xmethods
from libstdcxx.v6 import register_libstdcxx_printers
register_libstdcxx_printers (None)
class SpimplGetWorker(gdb.xmethod.XMethodWorker):
def __init__(self, elem_type): self.elem_type = elem_type
def get_arg_types(self): return None
def get_result_type(self, obj): return self.elem_type.pointer()
def __call__(self, obj):
ptr = obj['ptr_']
eval_string = '(*(%s*)(%s)).get()'%(ptr.type, ptr.address)
return gdb.parse_and_eval(eval_string)
class SpimplDerefWorker(SpimplGetWorker):
def __init__(self, elem_type): SpimplGetWorker.__init__(self, elem_type)
def get_arg_types(self): return None
def get_result_type(self, obj): return self.elem_type
def __call__(self, obj):
return SpimplGetWorker.__call__(self, obj).dereference()
class SpimplMethodsMatcher(gdb.xmethod.XMethodMatcher):
def __init__(self):
gdb.xmethod.XMethodMatcher.__init__(self, 'spimpl')
self._method_dict = {
'operator->': libstdcxx.v6.xmethods.LibStdCxxXMethod('operator->', SpimplGetWorker),
'operator*': libstdcxx.v6.xmethods.LibStdCxxXMethod('operator*', SpimplDerefWorker),
}
self.methods = [self._method_dict[m] for m in self._method_dict]
def match(self, class_type, method_name):
if not re.match('^spimpl::impl_ptr<.*>$', class_type.tag):
return None
method = self._method_dict.get(method_name)
if method is None or not method.enabled:
return None
return method.worker_class(class_type.template_argument(0))
gdb.xmethod.register_xmethod_matcher(None, SpimplMethodsMatcher())
end
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