Tom Dalling - Latest Comments

Re: Model View Controller Explained

Chris — Tue, 10 Jan 2012 22:02:22 -0000

Woah, wacky #ifdef intendation alert!

Re: Implementing Your Own Cocoa Bindings

Bastian Bechtold — Thu, 01 Dec 2011 07:37:54 -0000

Hi Tom,

thanks a lot for that piece of code! I used your code to make bindings work in a custom subclass of NSTextField which reacts to scrolling.

Re: Model View Controller Explained

Snehal Masne — Sun, 13 Nov 2011 01:56:50 -0000

Thank you so much for providing such a good explanation for MVC.. clarified many doubts :)

Re: How To Set Up A Secure Git Server At Home (OSX)

Tom Dalling — Thu, 27 Oct 2011 07:18:11 -0000

I haven't done a whole lot of ssh config before, so I'm not sure how to do that I'm afraid.

Re: How To Set Up A Secure Git Server At Home (OSX)

Nebu — Thu, 27 Oct 2011 05:38:09 -0000

Is there a possibility to disable the password authentication only for the git user? According to "man ssh_config" this should be possible by editing ~/.ssh/config the same way as you suggested to edit /etc/sshd_config (sans the root-part of course), but I can't seem to get it running...

Re: Model View Controller Explained

Hsharif2 — Sun, 02 Oct 2011 14:05:17 -0000

Awesome - great explanation, thanks. Appreciate the benefits write up - helps understand the competitive edge of using MVC

Re: Coding Tip: Have A Single Exit Point

Rick — Wed, 28 Sep 2011 09:46:45 -0000

It's a dated concept that is as relevant today as it was when Djikstra first proposed it. If you are in a professional shop, multiple exits in your methods, unless handling unexpected exceptions, will normally fail your code during review.

The principles of structured programming are to be adhered to whenever possible... any developer breaking with them today, in my opinion, should be viewed as a novice.

Re: How To Set Up A Secure Git Server At Home (OSX)

Benjamin Kreeger — Mon, 19 Sep 2011 23:43:22 -0000

Actually AFAIK, git comes installed on Lion by default, which means you shouldn't have to change any user's path to find it. I think it's at /usr/bin/git now.

Re: How To Set Up A Secure Git Server At Home (OSX)

Matt — Fri, 16 Sep 2011 14:43:23 -0000

Hi Tom,

Just wanted to say thanks for this guide, really helped me get my remote git server setup on my home machine.

Good work.
Matt.

Re: Model View Controller Explained

Guest — Fri, 09 Sep 2011 06:57:07 -0000

One of the better high level explanations I've seen. Thanks.

Re: How To Set Up A Secure Git Server At Home (OSX)

Tom Dalling — Tue, 02 Aug 2011 00:38:36 -0000

I haven't installed Lion yet, but try adding this line to the bottom of /etc/profile (in addition to step 4):

[ -r "$HOME/.bashrc" ] && source "$HOME/.bashrc"

It looks like .bashrc isn't run by default anymore, but this should make it run according to: http://natelyman.com/index.php...

Re: How To Set Up A Secure Git Server At Home (OSX)

Maddicken — Mon, 01 Aug 2011 16:55:04 -0000

How should step 4 "echo 'export PATH="$PATH:/usr/local/git/bin/"' >> ~/.bashrc" be changed to work on OSX Lion?

Re: Model View Controller Explained

pianite — Sat, 23 Jul 2011 11:54:21 -0000

I have never gotten MVC before now, great article, thanks much for the help!

Re: For those who have never used Objective C

Priyavarshini13 — Mon, 11 Jul 2011 23:36:17 -0000

its gud. well, is TOM similar to objective C? what is TOM exactly?????? pls reply.

Re: For those who have never used Objective C

willc2 — Fri, 01 Jul 2011 03:36:24 -0000

Box a large number of parameters in an NSDictionary, wrap the method call in your own method that checks the dict and supplies reasonable defaults for missing keys. Easy peasy lemon squeezy.

Re: Model View Controller Explained

Mark Hughes — Mon, 27 Jun 2011 06:18:37 -0000

I still don't get it 100%, but this helped me slightly understand it more. Thankyou!

Re: Why performSelector: Is More Dangerous Than I Thought

Steven Parkes — Thu, 31 Mar 2011 16:44:14 -0000

Thanks. Not sure how long it would have taken me to ferret this out ...

Re: Implementing Your Own Cocoa Bindings

Tom Dalling — Wed, 30 Mar 2011 02:03:09 -0000

Sorry, I've been meaning to get around to this for ages. In the mean time, have a look at mmalc's examples if you haven't already:

http://homepage.mac.com/mmalc/...

Re: SOLID Class Design: The Liskov Substitution Principle

Tom Dalling — Wed, 30 Mar 2011 01:58:10 -0000

Yes, in that respect this Bird/FlightfulBird example isn't great. If this were real software, I wouldn't use subclassing for every different type of bird. I'd just have a single Bird class, with a "setCanFly" method on it. That would make the whole problem go away.

When you say that your code snippet looks similar to the "Solution 1" code and therefor violates the OCP, I'd say it's actually more similar to the "Solution 2" code which doesn't violate the OCP. This is because when you make a new flightless bird class, you don't have to modify the ArrangeBirdInPattern function. In "Solution 1", you have to modify the function every time a new flightless bird class is created.

Like most software development advice, the LSP is just a rule of thumb. You can think of an LSP violation as a kind of code smell. It indicates that there may be a better way to structure the code.

As for the Java exceptions, I had a quick google (doesn't that sound dirty) and found this:

class: java.nio.ByteBuffer
method: public ByteBuffer put(ByteBuffer src)
throws: ReadOnlyBufferException (extends UnsupportedOperationException) - If this buffer is read-only

If you have a subclass of ByteBuffer that is read-only, I would say that it does violate the LSP. If you can never call "put", then it shouldn't have a "put" method at all. You could get around this by having two interfaces like ReadableByteBuffer and WritableByteBuffer. Then you can choose not to implement WritableByteBuffer if the class is read-only.

Re: SOLID Class Design: The Liskov Substitution Principle

Noemail — Sat, 26 Mar 2011 19:53:49 -0000

Hi Tom,

from a software architecture point of view I can fully agree to you. Subclassing the Bird for the FlightfulBird does make sense to group the flying ones alltogether. It is a reasonable choice both from a software design point of view and the semantically perspective.

But in practice the downsides stay exactly the same. To implement an apropriate ArrangeBirdInPattern-method you need to approximately do the following:

void ArrangeBirdInPattern(Bird* aBird)
{
FlightfulBird * aFlyingOne= dynamic_cast<flightfulbird *="">(aBird);
if(aFlyingOne)
ArrangeBirdInSky(aFlyingOne);
else
ArrangeBirdOnGround(aBird);

}

That looks pretty similar to the "blatant violation of the Open Closed Principle" earlier in this article. The difference is the use of an (abstract) superclass or interface instead of a single concrete subclass of Bird.

Did I get something wrong or is the LSP rather an academic subtleness and a design faux pas that a practical problem?

Besides in the Java Collection Framework the use of UnsupportedOperationException is pretty common (Collections.unmodifiableList()). The interface List itself even declares that such an Exception may be throws. Is this a violation of LSP?

Best regards
Andy</flightfulbird>

Re: Implementing Your Own Cocoa Bindings

nonamelive — Tue, 25 Jan 2011 21:09:54 -0000

Hi Tom,

Could you please give me an working example project of your code? I couldn't make it work since I'm not so sure where to put these codes, especially where to write [self propagateValue:newColor forBinding:@"color"];. Thanks in advance. My email is nonamelive#gmail.com

Re: SOLID Class Design: The Dependency Inversion Principle

Rooor Gh — Tue, 12 Oct 2010 14:30:12 -0000

can a mouse burn my mother board ?? and how plz?

Re: Crack an MD5 hash in less than a second

Adiga Hacker — Sun, 26 Sep 2010 17:06:06 -0000

Not cracked in less than a second precomputed passwords are actully a password and its md5 hash stored in a database then a matching will be checked for the hash you entered.

this could prove helpful if the password you choose is 7 chars or less in length, but to generate a database with 8 chars or more with alpha(small and capital)+numbers+special chars will take huge amount of space and also long generating time ...

for an 8 chars pass of alpha either small or capital with numbers and up to 10 allowable special chars, the pass space is 72^8+72^7+72^6 .... + 72^1 ... assuming a minimal size of 40 bytes as space for the pass + the hash ... my computer wont give an answer for that ... but it will take multi TBs with weeks if not months of generating ....

wither your pass is salted or not ... choose it to be 9 chars or more, with at least 1 number, 1 special char, 1 alpha capital and the rest as alpha small and your safe from getting your pass cracked as the chances of you being tricked into a false login or having your session stolen will be 1000s of time greater of your pass being cracked ....

Re: Why Inline Comments Are Generally a Bad Idea

Tom Dalling — Fri, 27 Aug 2010 20:49:37 -0000

Sage advice.

Re: Why Inline Comments Are Generally a Bad Idea

Greg Jorgensen — Fri, 27 Aug 2010 17:55:59 -0000

"Don't just echo the code with comments -- make every comment count."

"Make sure comments and code agree."

"Don't comment bad code -- rewrite it."

from "The Elements of Programming Style" by Kernighan and Plauger, 1974.