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Re: Strange crash in __objc_resolve_class_links

From: Dr. H. Nikolaus Schaller
Subject: Re: Strange crash in __objc_resolve_class_links
Date: Wed, 16 Feb 2011 16:56:00 +0100

> Yes, if the dot notation had been properly considered then it would have 
> enforced these additional requirements:
> - Accessor methods supplied for properties must not have side effects
> - Accessor methods supplied for properties must always return the value 
> provided for the last set operation.
> - Only methods declared with @property may be called with the dot notation
> If they had made these requirements, then the dot notation would have added 
> something of value to the language.  At present, it is semantically 
> equivalent to a message send and may be used interchangeably with a message 
> send.  Since it is semantically equivalent, it does not provide any more 
> information to the reader or to the compiler, it just does something that 
> looks like a field access (which is one of the fastest operations in C) and 
> actually makes it into a message send or two (which are an order of magnitude 
> slower), making it hard to reason about the behaviour of the code.  

As far as I remember the dot notation was introduced to make Obj-C more 
to Java and C++ programmers (especially for the iPhone).

So this is not a "missing" feature that was finally implemented by Obj-C 2.0.
Obj-C 1.0 was already complete and well designed enough to solve all
computing problems since 15 years.

Therefore, most long-time Obj-C programmers don't like the new features of 
Obj-C 2.0
(because many of them don't add value) and the newcomers love them because they
look familiar (but are not on a closer look).

Sometimes it is argued that the dot notation makes writing code faster and makes
it easier to read.

I recently back-ported some sample code which was a horrible mixture of
dot notation and message sending.

Nevertheless it took me just 20 minutes to replace them all and even replace
the @property and @synthesize by old-fashioned getter/setter code.

So the saving of programmer's time is probably not that much. Obj-C 1.0
did assume a write once read many time (and even years later) policy.
So spending time when writing doesn't count too much.

The most interesting and powerful addition of Obj-C 2.0 are IMHO blocks.
Although there is also something to criticise that the ^ syntax also appears
to be suboptimal.

But we won't change this - unless we work on Obj-C 3.0 and can deprecate all
this in 4.0.

Just my 2ct to this topic,

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