Re: Question on file GSString.m

[Fred Kiefer]

On 14.08.2011 22:57, Richard Frith-Macdonald wrote:
> On 14 Aug 2011, at 21:20, Fred Kiefer wrote:
>
> > I just noticed that we have lots of reimplementation of NSString
> > methods in the sub classes in GSString.m. Some of these are
> > actually needed like implementing
> > -initWithBytesNoCopy:length:encoding:freeWhenDone:, many others
> > look plain wrong. Why would we duplicate code here, in some cases
> > even in a worse form? After the current code freeze on base, could
> > somebody please go through this file and clean out the duplicated
> > methods?
>
> Subclasses are *supposed* to reimplement the methods of a class
> cluster ... 1. the primitive methods have to be implemented for the
> classes to function at all 2. many/most other methods need to be
> implemented in terms of the concrete ivars actually used ... so we
> get decent performance.
>
> There shouldn't be any real duplication of code, but there should be
> a *lot* of methods re-implemented ...  to access the 8 or 16 bit
> character data within the strings directly.  These should *not* be
> 'cleaned out' since they are essential for decent performance.

There seems to be a disagreement here, so lets look at one example.
GSPlaceholderString has this method:

- (id) initWithCharacters: (const unichar*)chars
                   length: (NSUInteger)length
{
  return [self initWithBytes: (const void*)chars
                      length: length * sizeof(unichar)
                    encoding: NSUnicodeStringEncoding];
}

NSString has the following corresponding method:

- (id) initWithCharacters: (const unichar*)chars
                   length: (NSUInteger)length
{
  return [self initWithBytes: chars
                      length: length * sizeof(unichar)
                    encoding: NSUnicodeStringEncoding];
}

I don't quite see how the only difference (the type cast) is "essential 
for decent performance".

I do understand that what you wrote is the basic idea of what should go 
into this file. I just have the impression that at the moment this isn't 
what is in the file and I would like to see that corrected. I also know 
that this has to be done very carefully as just using the implementation 
in NSString might result in circular call sequences or very bad performance.