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mulle-objc: present and absent language features

Continued from mulle_objc: inheriting methods from protocols of the mulle_objc series.


Updated: 7. November 2016

Objective-C is now a hybrid of many languages. The timeline being approximately this:

ObjC 1.0:      C  plus Smalltalk
   <- appeasement of the Java Noobs
ObjC++
ObjC 2.0
   <- usurpation by the C++ Flagellants

mulle_objc is supposed to put the basis of Objective-C back to ObjC 1.0 and cherrypick improvements from the later versions.

Here is a list of what's going on and what will be going on and what will not happen. Taking most of the terminology from:

  1. Wikipedia: Objective-C
  2. Apple: Objective-C Feature Availability Index
  3. NSHipster: @

The separation between Compiler, Runtime and Language is of course a bit arbitrary.

Language

Topic State
BOOL supported: but it is an int. If you really need to use bool use _Bool.
@"string" supported
@1, @(), ... planned: what is known as "Literals"
NSArray *foo; foo[ 1] not planned: [^1] what is known as "Subscripting"
@defs() supported
@encode() supported: 90% the same as the Apple runtime
@package never: will produce an error
@property supported
@autoreleasepool supported
@synchronized() not planned
@compatibility_alias unknown
@try @catch supported
for ( i in x) supported: what is known as "Fast Enumeration"
nonatomic supported
atomic nonatomic not planned
atomic as default never
instancetype supported
generics never
nullable not planned: will produce an error [^2]
nonnullable supported
property dot syntax not planned: [^1]
Protocol never: you have to use PROTOCOL instead of Protocol *
weak, strong never
__bridge will be a nop #define (also __bridge_retained, __bridge_transfer)
__unsafe_unretained could be a nop #define (_autoreleasing)

Compiler

Topic State
Default synthesis supported
ARC never, but look below for AAM
Exceptions supported
static NSStrings supported
variadic arguments (:...) supported, but not compatible to <stdarg.h>

Runtime

Topic State
Non-fragile ivars never
^blocks not planned: [^3]
Fast enumeration supported
ObjectiveC++ never: But the mulle-objc instance memory layout should be this->__vtab compatible to have dual facing objects.
Class extensions never: at least when you want to add instance variables
Modules not planned

Other "planned" features

For some of the "supported" features like protocol inheritance, please read the complete series.

Topic State
AAM supported: a much simpler successor to ARC called "Always Autoreleased Mode"
Generated parameter compliancy asserts planned: with a special compiler option each object parameter of a method will be checked with NSParameterAssert for class compliancy. Here nonnullable will be useful.
Method chaining technically supported: you can search the runtime to supply you with the overridden methods. But it's slow.

[^1] : This is basically operator overloading, which is un-C like.

[^2] : Superflous keyword, ObjC is by design nullable. It only makes sense to adorn non-nullable parameters.

[^3] : GCD is a Apple technology, that really needs kernel support to work well. lambdas are not a part of C11. Generally I find blocks unconvincing. It might be an idea to make NSInvocations out of block syntax ?


Glossary

Wording Meaning
supported should work already
will be supported must work with the first release
not supported might just accidentally work
planned may not be in the first release
unknown neither "planned" not "not planned"
not planned never say never, but this probably won't happen
never sometimes you have to say never :)

Continue to mulle-objc: the trouble with property


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