On 2014-06-24 02:30, ed wrote:
I'm attempting a 64 bit port of DWT and I'd like some feedback on API
changes.
My initial preference was no changes to existing API in order to ease
future updates from SWT proper. But of course that requires casts and I
suspect they will bubble to the surface and be exposed to end-users of DWT.
So now I'm leaning towards API changes of this sort:
/// Extension to String
public int indexOf( in char[] str,
char searched,
int fromIndex ){cast(int)...cast(int)...}
becomes
/// Extension to String
public ptrdiff_t indexOf( in char[] str,
char searched,
ptrdiff_t fromIndex) {...}
This maintains sign compatibility with the original API but may require
some changes to existing code. For example:
---
// Fails 64 bit, works 32 bit
int idx = indexOf("astring", 't', 1);
// Works 64 bit, Fails 32 bit
long idx = indexOf("astring", 't', 1);
// Works 64 bit and 32 bit
auto idx = indexOf("astring", 't', 1);
----
Does anyone have an alternative preferred approach to portable 32/64 bit
code?
I usually try to think like this, in some kind of priority list:
1. Follow system/native libraries - Example of this is when a system
library uses pointers then the SWT code will use an "int/long". In DWT I
would use the original pointer type
2. Follow the original SWT code - We want to make porting of future
versions of SWT as easy as possible
3. Do what's most appropriate in D
In this case I would use "size_t" because that is the native type D uses
for array indexes. This is what I've done in the Cocoa port, it's ported
to support both 32bit and 64bit form the start.
One possibility is separate code bases for 32 and 64 bit, as per SWT
proper. This is not my preference but I am happy to do it if people feel
it would be better this way.
I think it should be only one code base. SWT is actually only one code
base. They have a tool that converts between 32bit and 64bit. They make
separate releases but the it's only one repository. But D has language
support that will make this easier: "alias", "version" and so on.
--
/Jacob Carlborg
