Specifically, take the old code that looks like this:
class Foo {
enum { X = 1, Y = 2 };
int kind;
}
... foo.kind = Foo::X; ...
and convert it to this:
class Foo {
enum class Kind : uint32_t { X = 1, Y = 2 };
Kind kind;
}
... foo.kind = Foo::Kind::X;
(In some cases the enumeration would not be in the class namespace,
such as when it is generally useful.)
The benefits are as follows:
* The type of the field gives a clear indication of intent, both
to humans and tools (such as binding generators).
* The compiler is able to automatically warn when a switch is not
exhaustive; but this is currently suppressed by the
default: ssassert(false, ...)
idiom.
* Integers and plain enums are weakly type checked: they implicitly
convert into each other. This can hide bugs where type conversion
is performed but not intended. Enum classes are strongly type
checked.
* Plain enums pollute parent namespaces; enum classes do not.
Almost every defined enum we have already has a kind of ad-hoc
namespacing via `NAMESPACE_`, which is now explicit.
* Plain enums do not have a well-defined ABI size, which is
important for bindings. Enum classes can have it, if specified.
We specify the base type for all enums as uint32_t, which is
a safe choice and allows us to not change the numeric values
of any variants.
This commit introduces absolutely no functional change to the code,
just renaming and change of types. It handles almost all cases,
except GraphicsWindow::pending.operation, which needs minor
functional change.
This will allow us to use non-POD classes inside these objects
in future and is otherwise functionally equivalent, as well
as more concise.
Note that there are some subtleties with handling of
brace-initialization. Specifically:
On aggregates (e.g. simple C-style structures) using an empty
brace-initializer zero-initializes the aggregate, i.e. it makes
all members zero.
On non-aggregates an empty brace-initializer calls the default
constructor. And if the constructor doesn't explicitly initialize
the members (which the auto-generated constructor doesn't) then
the members will be constructed but otherwise uninitialized.
So, what is an aggregate class? To quote the C++ standard
(C++03 8.5.1 §1):
An aggregate is an array or a class (clause 9) with no
user-declared constructors (12.1), no private or protected
non-static data members (clause 11), no base classes (clause 10),
and no virtual functions (10.3).
In SolveSpace, we only have to handle the case of base classes;
Constraint and Entity have those. Thus, they had to gain a default
constructor that does nothing but initializes the members to zero.
The SolveSpace top-level directory was getting a bit cluttered, so
following the example of numerous other free-software projects, we move the
main application source into a subdirectory and adjust the build systems
accordingly.
Also, got rid of the obj/ directory in favor of creating it on the fly in
Makefile.msvc.
EvilSpirit
whitequark
Daniel Richard G