Tom Dalling

Hilarious Massive Facebook Privacy Flaw

Tom — Thu, 25 Feb 2010 02:26:57 +0000

My girlfriend just acquired a strange bug with sending private messages in Facebook. Firstly, she tries to send a normal private message like so: And then, it sends it to some completely random person that she’s not even friends with. So much for "private" messages. I tested it in a different browser on a different computer, and it [...]

SOLID Class Design: The Interface Segregation Principle

Tom — Thu, 18 Feb 2010 13:17:15 +0000

This is that last part of a five part series about SOLID class design principles by Robert C. Martin. The SOLID principles focus on achieving code that is maintainable, robust, and reusable. In this post, I will discuss the Interface Segregation Principle. The Interface Segregation Principle (ISP): Clients should not be forced to depend upon interfaces [...]

SOLID Class Design: The Dependency Inversion Principle

Tom — Sat, 19 Dec 2009 07:40:54 +0000

This is part four of a five part series about SOLID class design principles by Robert C. Martin. The SOLID principles focus on achieving code that is maintainable, robust, and reusable. In this post, I will discuss the Dependency Inversion Principle. The Dependency Inversion Principle (DIP): High level modules should not depend upon low level modules. [...]

SOLID Class Design: The Liskov Substitution Principle

Tom — Sat, 21 Nov 2009 06:49:27 +0000

This is part three of a five part series about SOLID class design principles by Robert C. Martin. The SOLID principles focus on achieving code that is maintainable, robust, and reusable. In this post, I will discuss the Liskov Substitution Principle. The Liskov Substitution Principle (LSP): functions that use pointers to base classes must be able [...]

SOLID Class Design: The Open Closed Principle

Tom — Sat, 14 Nov 2009 09:22:03 +0000

This is part two of a five part series about SOLID class design principles by Robert C. Martin. The SOLID principles focus on achieving code that is maintainable, robust, and reusable. In this post, I will discuss the Open Closed Principle. The Open Closed Principle (OCP): You should be able to extend a classes behavior, without [...]

SOLID Class Design: The Single Responsibility Principle

Tom — Thu, 12 Nov 2009 07:37:12 +0000

This is part one of a five part series about SOLID class design principles by Robert C. Martin. The SOLID principles focus on achieving code that is maintainable, robust, and reusable. In this post, I will discuss the Single Responsibility Principle. The Single Responsibility Principle (SRP): A class should have one, and only one, reason to [...]

Why Inline Comments Are Generally a Bad Idea

Tom — Thu, 08 Oct 2009 06:20:03 +0000

Bellow is a single function commented in two different ways. Which one is better? NSString* MD5StringOfString(NSString* inputStr) { //UTF8 encoding is used so the hash can be compared with hashes of ASCII strings NSData* inputData = [inputStr dataUsingEncoding:NSUTF8StringEncoding]; unsigned char outputData[CC_MD5_DIGEST_LENGTH]; CC_MD5([inputData bytes], [inputData length], outputData); NSMutableString* hashStr = [NSMutableString string]; int i = 0; for (i = 0; i < CC_MD5_DIGEST_LENGTH; ++i) [hashStr appendFormat:@"%02x", [...]

Coding Tip: Replace Complicated Conditions With Boolean Variables

Tom — Sat, 03 Oct 2009 09:02:27 +0000

Consider the following if statement: if(dragOperation != NSDragOperationCopy && NSPointInRect(currentMouseLocation, self.bounds)){ //do something } Even though you may have worked out what the condition represents, it probably took you a little longer than it should. It’s complicated, making it time consuming to read, and prone to bugs upon modification. Thankfully, there is an easy remedy: BOOL [...]

MD5 Hashes in Cocoa

Tom — Thu, 24 Sep 2009 03:12:25 +0000

Let’s jump straight into the code: #import <CommonCrypto/CommonDigest.h> NSString* MD5StringOfString(NSString* inputStr) { NSData* inputData = [inputStr dataUsingEncoding:NSUTF8StringEncoding]; unsigned char outputData[CC_MD5_DIGEST_LENGTH]; CC_MD5([inputData bytes], [inputData length], outputData); NSMutableString* hashStr = [NSMutableString string]; int i = 0; for (i = 0; i < CC_MD5_DIGEST_LENGTH; ++i) [hashStr appendFormat:@"%02x", outputData[i]]; return hashStr; } Now for the explanation. First, the input string is encoded into UTF8 data so that the hash comes out the same [...]

Coding Tip: Use The Ternary Conditional Operator

Tom — Wed, 09 Sep 2009 06:01:24 +0000

The ternary conditional operator (?:) can be used as a short-hand version of an if statement. It is a feature of many languages. For example, this code: int height; if(isTall) height = 50; else height = 10; can be better written as: int height = isTall ? 50 : 10; The ?: operator is good for [...]