Comments for Andy Palmer

Comment on Returning ‘null’ Considered Dishonest by Andy Palmer

Andy Palmer — Fri, 16 Mar 2012 19:19:00 +0000

I disagree (strongly) with the idea of exceptions being exceptional. They’re actually a half-arsed implementation of Lisp conditions (see Greenspun’s tenth rule)

I use exceptions when there is no point in the current logic path continuing. In the VendingMachine example, my friend Liz was able to write a Swing GUI that caught the exception and displayed it as an error message on the LCD display. Quite a result!To do that with return flags, I’d have to check the return flag, and then probably return a return flag to my caller, who’d have to return a return flag to his caller… and so on and so on.

Also, out parameters, by their very nature require mutable state… Not for me, thanks.

Comment on Returning ‘null’ Considered Dishonest by dragonlips

dragonlips — Fri, 16 Mar 2012 18:19:00 +0000

programming by exception for “normal business logic” is a bad idea.

This is a prime example of where a result flag + out params is appropriate.

bool GiveMeaDrink(out Drink)

So now you know if it’s safe or not off one call. If you need to know why give some way to get that info. But really you’re looking into the state of the vending machine at that point and it doesn’t really need to tell you since you already know you were supposed to provide the adequate amount of money first.

You could argue that it’s better to check state first then call. However that’s only partially successful since it would fail in a threaded environment.

however the point is Exceptions are “exceptional” (hense the name) not “normal” you didn’t give me enough money so you can’t have a drink is not exceptional in anyway. You just need to learn how to count your change better.

Comment on Pomodoro, AppleScript and Adium by LS

LS — Sun, 11 Mar 2012 11:45:00 +0000

I tried the above but didn’t work. I tried what Josh and Bobes suggested and it worked!

tell application “Adium” to go away with message “Pomodoro in Progress”

tell application “Adium” to go available

Thanks!

Comment on Finally, a use for checked exceptions by Andy Palmer

Andy Palmer — Fri, 18 Nov 2011 07:13:00 +0000

Good point. I have used Call Hierarchy, although when I read your comment, the idea that popped into my mind was ”debugging”.
I use “Find references in workspace (g)” a lot while refactoring (particularly while deleting code), but not Call Hierarchy. I’m not sure why; I’ll investigate that feeling next time I’m doing something like this.

Also, yes, the point of this is to leverage the compiler to help make sure we’ve removed all traces of the original null. I hate null checks within code I control, as that is indicative of a bad citizen (see Good Citizen)

Comment on Finally, a use for checked exceptions by Demian Alonso

Demian Alonso — Fri, 18 Nov 2011 01:29:00 +0000

Just a little contribution: Many ideas do have a way to search for references hierarchically. I now for sure that in Eclipse is called “call hierarchy”, but I am quite sure that on Idea is possible too, but I do not know the shortcuts

Still, the “it won’t compile” technic does prevent you from missing any case.

Comment on Finally, a use for checked exceptions by Andy Palmer

Andy Palmer — Thu, 17 Nov 2011 17:15:00 +0000

Good point. Although I would hope (for my sanity) that if there are catch everything blocks in the code, that they’re doing something sensible and I don’t need to go and change them at this point.
(I’ll probably go and rip them out at the soonest opportunity though )

Comment on Finally, a use for checked exceptions by Andy Palmer

Andy Palmer — Thu, 17 Nov 2011 17:14:00 +0000

Yes, although the advantage of this method is that it propagates _beyond the direct usages_.

Comment on Finally, a use for checked exceptions by Andy Palmer

Andy Palmer — Thu, 17 Nov 2011 17:12:00 +0000

The advantage is that it highlights the direct and indirect usages of someMethod. Direct usages is obviously trivial, it’s the indirect usages where the bugs usually lie.

Comment on Finally, a use for checked exceptions by Dileep Mandapam

Dileep Mandapam — Thu, 17 Nov 2011 16:28:00 +0000

I don’t see any other advantage of this refactoring technique , other than finding usages of “someMethod”

Comment on Finally, a use for checked exceptions by Ricky Clarkson

Ricky Clarkson — Thu, 17 Nov 2011 16:03:00 +0000

You’ll need to remove all the catch (Exception e) and catch (Throwable t) instances that inevitably end up in large code bases precisely because of checked exceptions.