Straw Poll: Return True or False?
-
OK, under what circumstances is that possible ? I have a linked list of any type, under what circumstances would you expect I'd be unable to remove an item ?
Christian Graus - Microsoft MVP - C++ Metal Musings - Rex and my new metal blog "I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
Christian Graus wrote:
OK, under what circumstances is that possible ? I have a linked list of any type, under what circumstances would you expect I'd be unable to remove an item ?
It would depend on the items in the list, if these items referenced a resource or database entry for example, and in this case the resource was unreachable or database was locked etc. Then you could fail to delete. Another example would be if the entry had a reference count that was higher than two meaning it was still in use. On reflection, throwing an exception would be a preferable to give a reason why the item could not be deleted. I think this has been mentioned in other replies in the thread.
Never argue with an imbecile; they bring you down to their level, and beat you with experience.
-
Christian Graus wrote:
OK, under what circumstances is that possible ? I have a linked list of any type, under what circumstances would you expect I'd be unable to remove an item ?
It would depend on the items in the list, if these items referenced a resource or database entry for example, and in this case the resource was unreachable or database was locked etc. Then you could fail to delete. Another example would be if the entry had a reference count that was higher than two meaning it was still in use. On reflection, throwing an exception would be a preferable to give a reason why the item could not be deleted. I think this has been mentioned in other replies in the thread.
Never argue with an imbecile; they bring you down to their level, and beat you with experience.
An exception can be expensive, it all depends on how often it may occur. But yes, I said from the start that it depends on the complexity of hte method. Interesting discussion that Chris started.
Christian Graus - Microsoft MVP - C++ Metal Musings - Rex and my new metal blog "I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
-
Here's a philosophical question: If you have a function that is meant to delete an item from a collection and the item you wish to delete doesn't exist, do you: 1. Return TRUE since the final outcome (not having that item) has been fulfilled, or 5. Return FALSE because since the function couldn't find the item, it couldn't actually delete it. Vote now.
cheers, Chris Maunder
CodeProject.com : C++ MVP
The 9 things Microsoft should be announcing at MIX07 (but won't)
I will return S_FALSE :)
"Some people believe football is a matter of life and death. I'm very disappointed with that attitude. I can assure you it is much, much more important than that. -- Bill Shankly"
-
An exception can be expensive, it all depends on how often it may occur. But yes, I said from the start that it depends on the complexity of hte method. Interesting discussion that Chris started.
Christian Graus - Microsoft MVP - C++ Metal Musings - Rex and my new metal blog "I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
Christian Graus wrote:
An exception can be expensive, it all depends on how often it may occur. But yes, I said from the start that it depends on the complexity of hte method.
From my COM/DCOM days, you could return a HRESULT, S_OK for found and deleted, S_FALSE for not found assumed deleted, and failed codes for each of the reasons for failure ;)
Christian Graus wrote:
Interesting discussion that Chris started.
Indeed! :-D
Never argue with an imbecile; they bring you down to their level, and beat you with experience.
-
Here's a philosophical question: If you have a function that is meant to delete an item from a collection and the item you wish to delete doesn't exist, do you: 1. Return TRUE since the final outcome (not having that item) has been fulfilled, or 5. Return FALSE because since the function couldn't find the item, it couldn't actually delete it. Vote now.
cheers, Chris Maunder
CodeProject.com : C++ MVP
The 9 things Microsoft should be announcing at MIX07 (but won't)
Depends on what do you mean by return value. Does it indicate if everything was ok (true) or something went wrong (false)? In that case, return TRUE if item to delete wasn't found. Or, does return value indicate if it deleted item or not? In that case, return FALSE if item to delete wasn't found.
"Throughout human history, we have been dependent on machines to survive. Fate, it seems, is not without a sense of irony. " - Morpheus "Real men use mspaint for writing code and notepad for designing graphics." - Anna-Jayne Metcalfe
-
Here's a philosophical question: If you have a function that is meant to delete an item from a collection and the item you wish to delete doesn't exist, do you: 1. Return TRUE since the final outcome (not having that item) has been fulfilled, or 5. Return FALSE because since the function couldn't find the item, it couldn't actually delete it. Vote now.
cheers, Chris Maunder
CodeProject.com : C++ MVP
The 9 things Microsoft should be announcing at MIX07 (but won't)
The function should return FALSE. Choosing to return a boolean value from such a function implies the fact that I use exceptions to handle errors. Otherwise, it would be a bad design decision to return a simple boolean value. The function outcome is expected to be this: The value is certainly removed after a call has been made. The return value tells me a nuance of how the operation has been executed - TRUE if the value was actually removed, FALSE if there wasn't anything to remove - and I may or may not use this extra information in my code. However, the return value is not there for error handling. If anything doesn't go according to the expected operating mode - For example the value to be removed has a state that doesn't allow removal - I will throw an exception. If I can't use exceptions then the return value should be an integer with return types documented. For example, I can use 0 for success and anything else for various error codes. This is the model widely used in Win32 APIs. HTH, Bogdan P.S: I'm glad to see this kind of questions are being asked.
-
Here's a philosophical question: If you have a function that is meant to delete an item from a collection and the item you wish to delete doesn't exist, do you: 1. Return TRUE since the final outcome (not having that item) has been fulfilled, or 5. Return FALSE because since the function couldn't find the item, it couldn't actually delete it. Vote now.
cheers, Chris Maunder
CodeProject.com : C++ MVP
The 9 things Microsoft should be announcing at MIX07 (but won't)
I wish I had a sense of Humor, I could join in the fun then. But I would tend to agree that Logically:- the function returns a value True or False therefore if there is no data to be deleted, you must return False, the data does not exist therefore cannot be deleted so the operation has not been completed. Clearly you NEED to know the operation has been completed, otherwise you would have written the function with a null return value, therefore if there is no data to delete there is a logical error which needs to be flagged and acted on as appropriate. as mentioned by another responder it may be a case of a missing database or some one not doing thier job properly and in need of being fired. Philosophically:- there is inssufficient information to answer the question, IE does it matter what the return value is? The question can of course be compared with that of "what is the sound of one hand clapping" Clearly there is insufficient information to correctly answer the question, no indication is given as to what the one hand is clapping against and the form (shape) of the hand at impact. for example if the hand was clapping against a smooth concrete surface and the hand was flat the result would be a slapping sound with an instant decay. If the hand was cupped then the sound would be more of a muffled thud. if however the hand was clapping against a large Bell, ( as the bell clapper would do) the resultant sound would be accompanied by a ringing note with a more prolonged decay. bet you are glad you asked now! Woz_a
-
Here's a philosophical question: If you have a function that is meant to delete an item from a collection and the item you wish to delete doesn't exist, do you: 1. Return TRUE since the final outcome (not having that item) has been fulfilled, or 5. Return FALSE because since the function couldn't find the item, it couldn't actually delete it. Vote now.
cheers, Chris Maunder
CodeProject.com : C++ MVP
The 9 things Microsoft should be announcing at MIX07 (but won't)
-
Here's a philosophical question: If you have a function that is meant to delete an item from a collection and the item you wish to delete doesn't exist, do you: 1. Return TRUE since the final outcome (not having that item) has been fulfilled, or 5. Return FALSE because since the function couldn't find the item, it couldn't actually delete it. Vote now.
cheers, Chris Maunder
CodeProject.com : C++ MVP
The 9 things Microsoft should be announcing at MIX07 (but won't)
I would vote the little known third option,
TRALSE, since this was neither TRUE nor FALSE and it might be nice to know the true outcome here...:-D
CleaKO
"I think you'll be okay here, they have a thin candy shell. 'Surprised you didn't know that.'" - Tommy (Tommy Boy)
"Fill it up again! Fill it up again! Once it hits your lips, it's so good!" - Frank the Tank (Old School) -
That's a bit of a large hammer to weild. What if you vaguely expect an item to be there but another process has removed it just before you do. Is an exception a good idea, considering that in the end it's not so much an error, but more of a "oh well" thing.
throw new NotThereShrugException();cheers, Chris Maunder
CodeProject.com : C++ MVP
The 9 things Microsoft should be announcing at MIX07 (but won't)
Chris Maunder wrote:
That's a bit of a large hammer to weild.
Not really. It encourages people to (properly) use the .Contains() method before calling the .Delete() method. Or in the case of file I/O, you would use the File.Exists() static method before firing off a .Delete().
Grim
(aka Toby)
MCDBA, MCSD, MCP+SB
SELECT * FROM users WHERE clue IS NOT NULL GO
(0 row(s) affected)
-
Chris Maunder wrote:
That's a bit of a large hammer to weild.
Not really. It encourages people to (properly) use the .Contains() method before calling the .Delete() method. Or in the case of file I/O, you would use the File.Exists() static method before firing off a .Delete().
Grim
(aka Toby)
MCDBA, MCSD, MCP+SB
SELECT * FROM users WHERE clue IS NOT NULL GO
(0 row(s) affected)
But what if your collection is actually a database? (I wasn't referring, literally, to a .NET collection)
cheers, Chris Maunder
CodeProject.com : C++ MVP
The 9 things Microsoft should be announcing at MIX07 (but won't)
-
If it failed it should throw an exception. Maybe you want a
TryDelete? -
Here's a philosophical question: If you have a function that is meant to delete an item from a collection and the item you wish to delete doesn't exist, do you: 1. Return TRUE since the final outcome (not having that item) has been fulfilled, or 5. Return FALSE because since the function couldn't find the item, it couldn't actually delete it. Vote now.
cheers, Chris Maunder
CodeProject.com : C++ MVP
The 9 things Microsoft should be announcing at MIX07 (but won't)
Test for existance first, then attempt delete.
-
That's right, the question didn't indicate that the method did anything more complex. And, if it did, it's possible an enum would be required if a return value was needed to indicate what occured.
Christian Graus - Microsoft MVP - C++ Metal Musings - Rex and my new metal blog "I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
:-D If I have to choose from them,I would choose FALSE. But I would like to design that function to return how many it would have deleted items. And if exception error would happen,that function would return negative number. Because to have more infomation makes that function more useful. But to make that function more useful makes programer more distressful.
-
Test for existance first, then attempt delete.
That's inefficient, the delete will do the check for existence (a second time).
-
I would vote the little known third option,
TRALSE, since this was neither TRUE nor FALSE and it might be nice to know the true outcome here...:-D
CleaKO
"I think you'll be okay here, they have a thin candy shell. 'Surprised you didn't know that.'" - Tommy (Tommy Boy)
"Fill it up again! Fill it up again! Once it hits your lips, it's so good!" - Frank the Tank (Old School)At times I use an enum;
{ Good , Bad , Ugly } -
But what if your collection is actually a database? (I wasn't referring, literally, to a .NET collection)
cheers, Chris Maunder
CodeProject.com : C++ MVP
The 9 things Microsoft should be announcing at MIX07 (but won't)
Chris Maunder wrote:
But what if your collection is actually a database?
Follow the already well-established database model and return an integer representing the number of rows affected. Because with a database, it's just as important to know that you deleted 150 rows as it would be to know that you didn't delete any. (More important, IMHO.)
Grim
(aka Toby)
MCDBA, MCSD, MCP+SB
SELECT * FROM users WHERE clue IS NOT NULL GO
(0 row(s) affected)
-
Here's a philosophical question: If you have a function that is meant to delete an item from a collection and the item you wish to delete doesn't exist, do you: 1. Return TRUE since the final outcome (not having that item) has been fulfilled, or 5. Return FALSE because since the function couldn't find the item, it couldn't actually delete it. Vote now.
cheers, Chris Maunder
CodeProject.com : C++ MVP
The 9 things Microsoft should be announcing at MIX07 (but won't)
I'm thinking enums: eLookHereMateYourAskingMeToDeleteSomethingThatJustDoNotExistYouTwit eYouCallThatAnIndexIveSeenBetterIndicesOnAFisherPriceCalculatorYouTwit eItsLockedAskMeLaterYouTwit eRaviAteItYouTwit eDeleteThisYouTwit eOKYouTwit Pretty much covers the most likely scenarios, and makes the error log a little more interetsing. A more difficult case can occur if the ham sandwich is deleted after Ravi has eaten half of it, especially if garbage collection is running in promiscuous mode. Then you should use a real programming laguage.
-
This is a trick questions. None of the answers are fully acceptable. The question doesn't leave room for a third option of returning a status code which can take at least 3 values. Then, the answer would be to just return a separate, third value if the element to be deleted wasn't found! In my philosophy classes I was thought there are actually three states of truth: true, false, and undecided.;) The reason we're stuck with just true and false in programming seems to have something to do with the 0 and 1 values of independent bits.
-
That's inefficient, the delete will do the check for existence (a second time).
How so? Psuedo Code if (list.contains(item)) { bool bOK = list.delete(item); //Do something here we bOK if you want } This would skip delete calls to items that no longer exist. The delete just deletes, it doesn't do a check on existance.