Inspired by MonomorphicArray I came up with another idea:
Create a subclass on NSMutableArray, that takes two blocks:
- AddBlock — a block that test, if one or more requirements are full filed and adds the object only, if its passes the test
- FailBlock — a block, that defines what happens, if the test was not successful.
The AddBlock could test for a certain class membership like
^BOOL(id element) {
return [element isKindOfClass:[NSString class]];
}
and the FailBlock can raise an exception, fail silently or add the element, that failed the test, to another Array. If no failBlock is provided, a default block will raise an error.
The blocks will define, if an array acts like an generic array, or as a filter.
I will give an complete example for the second case.
VSBlockTestedObjectArray.h
#import <Foundation/Foundation.h>
typedef BOOL(^AddBlock)(id element);
typedef void(^FailBlock)(id element);
@interface VSBlockTestedObjectArray : NSMutableArray
@property (nonatomic, copy, readonly) AddBlock testBlock;
@property (nonatomic, copy, readonly) FailBlock failBlock;
-(id)initWithTestBlock:(AddBlock)testBlock FailBlock:(FailBlock)failBlock Capacity:(NSUInteger)capacity;
-(id)initWithTestBlock:(AddBlock)testBlock FailBlock:(FailBlock)failBlock;
-(id)initWithTestBlock:(AddBlock)testBlock;
@end
VSBlockTestedObjectArray.m
#import "VSBlockTestedObjectArray.h"
@interface VSBlockTestedObjectArray ()
@property (nonatomic, retain) NSMutableArray *realArray;
-(void)errorWhileInitializing:(SEL)selector;
@end
@implementation VSBlockTestedObjectArray
@synthesize testBlock = _testBlock;
@synthesize failBlock = _failBlock;
@synthesize realArray = _realArray;
-(id)initWithCapacity:(NSUInteger)capacity
{
if (self = [super init]) {
_realArray = [[NSMutableArray alloc] initWithCapacity:capacity];
}
return self;
}
-(id)initWithTestBlock:(AddBlock)testBlock
FailBlock:(FailBlock)failBlock
Capacity:(NSUInteger)capacity
{
self = [self initWithCapacity:capacity];
if (self) {
_testBlock = [testBlock copy];
_failBlock = [failBlock copy];
}
return self;
}
-(id)initWithTestBlock:(AddBlock)testBlock FailBlock:(FailBlock)failBlock
{
return [self initWithTestBlock:testBlock FailBlock:failBlock Capacity:0];
}
-(id)initWithTestBlock:(AddBlock)testBlock
{
return [self initWithTestBlock:testBlock FailBlock:^(id element) {
[NSException raise:@"NotSupportedElement" format:@"%@ faild the test and can't be add to this VSBlockTestedObjectArray", element];
} Capacity:0];
}
- (void)dealloc {
[_failBlock release];
[_testBlock release];
self.realArray = nil;
[super dealloc];
}
- (void) insertObject:(id)anObject atIndex:(NSUInteger)index
{
if(self.testBlock(anObject))
[self.realArray insertObject:anObject atIndex:index];
else
self.failBlock(anObject);
}
- (void) removeObjectAtIndex:(NSUInteger)index
{
[self.realArray removeObjectAtIndex:index];
}
-(NSUInteger)count
{
return [self.realArray count];
}
- (id) objectAtIndex:(NSUInteger)index
{
return [self.realArray objectAtIndex:index];
}
-(void)errorWhileInitializing:(SEL)selector
{
[NSException raise:@"NotSupportedInstantiation" format:@"not supported %@", NSStringFromSelector(selector)];
}
- (id)initWithArray:(NSArray *)anArray { [self errorWhileInitializing:_cmd]; return nil;}
- (id)initWithArray:(NSArray *)array copyItems:(BOOL)flag { [self errorWhileInitializing:_cmd]; return nil;}
- (id)initWithContentsOfFile:(NSString *)aPath{ [self errorWhileInitializing:_cmd]; return nil;}
- (id)initWithContentsOfURL:(NSURL *)aURL{ [self errorWhileInitializing:_cmd]; return nil;}
- (id)initWithObjects:(id)firstObj, ... { [self errorWhileInitializing:_cmd]; return nil;}
- (id)initWithObjects:(const id *)objects count:(NSUInteger)count { [self errorWhileInitializing:_cmd]; return nil;}
@end
Use it like:
VSBlockTestedObjectArray *stringArray = [[VSBlockTestedObjectArray alloc] initWithTestBlock:^BOOL(id element) {
return [element isKindOfClass:[NSString class]];
} FailBlock:^(id element) {
NSLog(@"%@ can't be added, didn't pass the test. It is not an object of class NSString", element);
}];
VSBlockTestedObjectArray *numberArray = [[VSBlockTestedObjectArray alloc] initWithTestBlock:^BOOL(id element) {
return [element isKindOfClass:[NSNumber class]];
} FailBlock:^(id element) {
NSLog(@"%@ can't be added, didn't pass the test. It is not an object of class NSNumber", element);
}];
[stringArray addObject:@"test"];
[stringArray addObject:@"test1"];
[stringArray addObject:[NSNumber numberWithInt:9]];
[stringArray addObject:@"test2"];
[stringArray addObject:@"test3"];
[numberArray addObject:@"test"];
[numberArray addObject:@"test1"];
[numberArray addObject:[NSNumber numberWithInt:9]];
[numberArray addObject:@"test2"];
[numberArray addObject:@"test3"];
NSLog(@"%@", stringArray);
NSLog(@"%@", numberArray);
Note: This code is not fully tested. Probably some of the unimplemented method should be implemented for usage in real world programs.