null vs String.Empty

[Chris Maunder]

LOL. Yeah, I could definitely do public bool GetAString(out string aString) but, well... X|

cheers, Chris Maunder

CodeProject.com : C++ MVP

[Chris Maunder]

I love it how a discussion on programming techniques invariable leads to a general slamming of VB. Poor VB...

cheers, Chris Maunder

CodeProject.com : C++ MVP

[Shog9 0]

If by "fails" you mean "encounters a situation where it is completely unable to fulfill the requirements for which it was designed", then i go with Nemanja's technique: throw an exception. Otherwise, it depends on the situation. If the routine is designed such that the caller will need to take specific action in the event of failure, i'll return null. However, if i intend the return value to be used in the same manner regardless of whether the routine is able to actually produce anything interesting (retrieve a column value, format a date, etc.), then i'll return an empty string. In nearly all cases, this is a decision i would make prior to actually implementing the routine. In C++, it would effect my decision to use a return value of [CString|std::string|_bstr_t] vs. [LPCTSTR|char*|BSTR|etc.]. In a .NET language, it would merely change how i documented and called the routine.

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[Shog9 0]

Chris Maunder wrote:

but, well...

But, well, that would be entirely appropriate if you were returning a primitive type such as int, where (depending on the purpose of the routine) it might not have any potential values that could be considered "invalid". While it usually makes more sense to treat strings as reference types, if your interface returns only primitives and strings it might be worthwhile to treat them in a similar fashion, just for consistency.

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[Shog9 0]

Chris Maunder wrote:

Poor VB...

I have a meeting next week to discuss the redesign of a library, currently implemented in VB.NET and Excel. This is gonna cast a shadow over my entire weekend. No sympathy.

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[Shog9 0]

Zac Howland wrote:

Returning a string("") or CString("") would be almost equivalent to String.Empty.

Unless your return value is defined as LPCTSTR... at that point, it becomes a logic error. ;P

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[Andy Brummer]

Yeah, I really don't like that either, but it does signify that it is a performance hack optimization when you see it in code. Then again I only really care if it is a public method that is going to get reused all over the place. I much prefer string GetString() because it is so much more readable, and I normally don't worry about it too much because I've never run into a situation where throwing exceptions has been a performance problem. 95% of the performance problems I've run into have been lame database code that gets too friendly with the databse server.

---

I can imagine the sinking feeling one would have after ordering my book, only to find a laughably ridiculous theory with demented logic once the book arrives - Mark McCutcheon

[Andy Brummer]

Great, now I have to amend my statement. Yeah, if returning an empty string makes the general case for the client easier then yeah that is the way to go. I'd only do that in user interface code, because functions in other parts of an app should pretend they don't know how they are going to get used.

---

I can imagine the sinking feeling one would have after ordering my book, only to find a laughably ridiculous theory with demented logic once the book arrives - Mark McCutcheon

[Shog9 0]

Andy Brummer wrote:

I'd only do that in user interface code, because functions in other parts of an app should pretend they don't know how they are going to get used.

Right. :) I write a lot of UI code, so that tends to be the first scenario that occurs to me.

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[Judah Gabriel Himango]

Jeremy Falcon wrote:

even if it gets bad params

I'm a believer that once you start tolerating bad input, your whole system gets messed up. In my experience, it's best to stop when you get bad input, otherwise all sorts of things start going wrong. Of course, since you're writing C, exceptions are out of the question for you. The best you can do is return soon as you get bad input, and hope the caller checks your error code.

Tech, life, family, faith: Give me a visit. I'm currently blogging about: Dumbest. Movie. Title. Evaaar. The apostle Paul, modernly speaking: Epistles of Paul Judah Himango

[Zac Howland]

Chris Maunder wrote:

looks around at all the C# code lying about the place

:sigh: I've used C# so much that I completely forgot it also had a String.Empty ... :doh:

If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac

[Member 96]

Either depending on how critical it is.

My responsibility ends where your ability to think for yourself begins.

[Jeremy Falcon]

Judah Himango wrote:

I'm a believer that once you start tolerating bad input, your whole system gets messed up.

Um, nobody said to tolerate it. I said to let the caller know something was bogus. And, letting the caller know a value is messing up a system, I'd wager there were really other aspects in that system(s) that lead to the issues.

Judah Himango wrote:

Of course, since you're writing C, exceptions are out of the question for you. The best you can do is return soon as you get bad input, and hope the caller checks your error code.

Most people tend to use exceptions in a poor way. It's about program flow really.

Jeremy Falcon A multithreaded, OpenGL-enabled application.[^]

[Christian Graus]

String.Empty, of course. Just like I'd always use Environment.NewLine, even though I know what it is always going to be. Any sort of constant defined by the framework is there to be used, it documents your code and it means that you're conforming to the framework, assuming that one day it may exist on anothe platform where any of those values may concievably change. Just like I'd always use SW_HIDE and not 0, I know it won't change, but it doesn't hurt to do things properly.

Christian Graus - Microsoft MVP - C++ Metal Musings - Rex and my new metal blog

[Shog9 0]

Christian Graus wrote:

Just like I'd always use SW_HIDE and not 0

Uh, i think the choice was between String.Empty (== "") and null (== null)...

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[Christian Graus]

Oh - that's what I get for responding first thing in the morning. I *always* use string.IsNullOrEmpty to check strings, so the end result for me is the same.

Christian Graus - Microsoft MVP - C++ Metal Musings - Rex and my new metal blog

[Paul Watson]

Null in the Maunderverse but normally an exception in mine. I guess if it was in the context of nullable columns in a database then you could return null for a string return type. But I think a failure should be indicated by an exception, not a null that subsequent code will trip over without additional checking. Then again you could just start using Ruby and stop worrying... ;)

regards, Paul Watson Ireland FeedHenry needs you

Shog9 wrote:

eh, stop bugging me about it, give it a couple of days, see what happens.

[Jeremy Falcon]

It was just too tempting. I don't know. It's like, bashing VB is just there for the taking. :laugh:

Jeremy Falcon A multithreaded, OpenGL-enabled application.[^]

[Jeremy Falcon]

led mike wrote:

That's just foolish.

Unlike your foolish crap in the SB, mine was also a joke. I suspect in your attempt to "get back at me", reality escaped you. Now, so you don't seem crazy, this is where you reply saying yours was also a joke. But, we both know the reason you said it. And to that I say, next time try understanding what I'm saying when I say you're acting a fool rather than get all butt hurt and learn nothing.

Jeremy Falcon A multithreaded, OpenGL-enabled application.[^]

[led mike]

:laugh: Not at all. I never figured out what yours meant so the next time I saw you post I replied "That's just foolish", it doesn't mean anything. :-D

led mike