Naming Conventions: What to name a method that returns a boolean?

Question

I have an interface in C# that helps retrieving of data from a custom archive on server. The interface looks like this:

public interface IRetrieveData
{
    bool OkToRetrieve(SomeData data); // Method in question...
    bool RetrieveToLocal(SomeData data);
}

This interface is implemented by the clients that retrieve the data to the local database. There are different flavors of clients that have access to each others data. So, when the processing component calls IRetrieveData.OkToRetrieve right before actual retrieve, the call goes to the client code where the decision is made on whether the data should be retrieved or not.

At this point the client can return false and that piece of data is skipped or return true and the processing component calls RetrieveToLocal and send the data to the client which then processes it.

Where I am getting confused is whether to rename the method OkToRetrieve to just Retrieve or CanRetrieve or leave it as OkToRetrieve.

Does anyone have any suggestion?

`SafeToRetrieve`/`IsSafeToRetrieve`? – Candid Moon _Max_ Jun 27 '21 at 21:34 — Candid Moon _Max_, Jun 27 '21 at 21:34
Is a convention opinion-based? – Olivier Jacot-Descombes Jan 14 '23 at 15:10 — Olivier Jacot-Descombes, Jan 14 '23 at 15:10

score 102 · Accepted Answer · edited Jun 22 '17 at 13:49

102

IsRetrievable()

I think that a method that returns a boolean value should be named as a yes-no question.

edited Jun 22 '17 at 13:49

participant

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answered Sep 03 '09 at 00:24

Aziz

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I like the `is` part, but just because it is retrievable doesn't mean it's OK to retrieve it. I would call it `isOKToRetrieve` – Thomas Owens Sep 03 '09 at 00:26
1

Absolutely. The "Is" prefix is a coding standard on our team. – Rap Sep 03 '09 at 00:28
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ALl I would add TO Ariz' answer, (And this is a nitnoi) is to make a distinction as t oexactly what the function is checking... Is it whether the data IS retrievable, or whether the current code CAN retrieve it, or whether it SHOULD rectrieve it, etc. etc. e.g., if the function is examining the validity of the data and 'authorizing the retrieval when the data passes some set of conditions, then IsComplete() or IsValid, or IsTransactionallyConsistent, or something that describes the nature of the check that is being done to 'pass' might be somewhat more informative. – Charles Bretana Sep 03 '09 at 00:31
@bpayne Uhhh how would you use "Is" for something like shelf.HasProducts() or body.ContainsKnife()? – mxmissile Sep 03 '09 at 00:33
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mxmissile: I would call those methods `isEmpty()` (and, if the shelf has a limit, `isFull()`) and I would NEVER make a `containsKnife()` method, but rather a `contains()` method that accepts a parameter. And yes, `contains()` is an exception to the is rule. – Thomas Owens Sep 03 '09 at 00:37
I think what Aziz has suggested about having it as a Yes No question is right. So, as Thomas Owens has commented above I am going with IsOkToRetrieve(). – ashtee Sep 03 '09 at 01:55
@bpayne fair enough, i'm assuming isEmpty() and isFull() would contain parameters if shelf could contain more than "products"? – mxmissile Sep 03 '09 at 23:36
@Aziz This seems to be the popular convention on SO but for some reason, I am not sure why, there is something I don't like about it. – theblang Jan 30 '13 at 15:58
Name the function as a statement, not a yes/no-question. `IsRetrievable` might be interpreted as an abbreviated "is it retrievable?" which is an actual yes/no question, or "it is retrievable", which is a statement. I would use the latter, since then if statements would read better. Another example, which makes it more obvious: `if AreFiltersTheSame(x,y)` uses a yes/no question, and `if FiltersAreTheSame(x,y)` uses a statement. I prefer the latter, since it reads better (especially with long if statements with many conditionals). In your case `IsRetrievable` works fine as a statement though. – Magne Jun 04 '14 at 13:17
@Magne Long if statements with many conditionals should be refactored because it is unclear what the code does. What about when you have ternaries `myVar = FiltersAreTheSame(x,y) ? 1 : 0`, how does that read for you? – Frederik Krautwald Apr 25 '15 at 09:41
@FrederikKrautwald Yes, it probably should be refactored, but often isn't, so one probably has to deal with it whether one likes it or not (due to other developers not refactoring, or you not taking the time to refactor their code). Ternaries do not read as well. Good point. I see regular if statements used more often though, so I would lean towards optimising for that. – Magne Apr 25 '15 at 14:45

score 25 · Answer 2 · answered Sep 03 '09 at 00:27

25

Allways name boolean methods with names similar to questions that can be answered Yes or No.

In your case, CanRetrieve would be a good name (just to use your own suggestion).

answered Sep 03 '09 at 00:27

eKek0

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`can` != `should`. the customer code does not prevent you from retrieving it just recommend, therefore I think `ShouldRetrieve`is a better name, as @dannie.f proposed. – problemofficer - n.f. Monica Aug 03 '17 at 19:01

score 23 · Answer 3 · answered Jun 01 '11 at 16:54

23

How about using the prefix 'should'?

ShouldRetrieve(SomeData data);

answered Jun 01 '11 at 16:54

dannie.f

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This is the best answer imho, because the name describes exactly what information the method returns. It is a recommendation and not an ability. – problemofficer - n.f. Monica Aug 03 '17 at 19:03

score 15 · Answer 4 · answered Sep 03 '09 at 00:31

15

Methods mean action. Therefore, I prefer method names to start with a verb. How about?

CheckIsRetrievable(SomeData data)

answered Sep 03 '09 at 00:31

Mehmet Aras

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"Is" is a verb... – Marcel Lamothe Dec 01 '09 at 14:38
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It depends upon what the meaning of the word 'is' is. – Night Owl Feb 19 '14 at 02:54
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@MarcelLamothe "Is" does not implicit an action like "check" or "collect" but a state. – KnorxThieus Jan 30 '17 at 12:58
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`if(IsRetrievable(data))` imho reads much better than `if(CheckIsRetrievable(data))`. And I think if-clauses are where boolean returning functions are mostly used. – problemofficer - n.f. Monica Aug 03 '17 at 18:57
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I really don't like `check` at prefix of a method. It sound a little bit redundant – You're awesome Aug 29 '18 at 00:47
@problemofficer-n.f.Monica If you are inspecting an obect and it has an isRetrievable item, it does not convey whether it is an attribute or a method. – run_the_race Feb 13 '22 at 18:49
for me in this case the bool return value implies that the check has taken place or not. but not whether isRetrievable is true or false. – Welcor Apr 15 '23 at 19:57
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I like this as it means you can write the variable name without shadowing the function name: `const isRetrievable = checkIsRetrievable(SomeData data)` – Will Stone May 10 '23 at 12:02

score 15 · Answer 5 · answered Jan 17 '19 at 23:20

15

Generally, methods/functions indicate actions so they should prefixed with verbs. e.g. check, get, make, etc.

The common naming convention for boolean variables is to prefix them with helping verbs e.g. is, does, will, can

I would think that the combination of the two conventions would lead to a pretty good, discerning pattern. So getIsRetreivable() or checkIsRetrievable() would look pretty good to me.

answered Jan 17 '19 at 23:20

Cary Meskell

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I like this one as well. Most answers suggest just the is, but to me just prefixing with is would indicate a boolean var, not a function that returns a boolean. – Thiago Pereira Maia Nov 01 '21 at 15:12

score 10 · Answer 6 · answered Feb 25 '14 at 11:42

10

Depends on your use case. I like to prefix them with words such as 'is', 'does' or 'Can': IsSomePropertySoAndSo, DoesNounSupportFeature and as your example CanVerb

answered Feb 25 '14 at 11:42

arviman

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score 8 · Answer 7 · answered Sep 03 '09 at 00:32

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In this specific case, I'd probably name it:

public bool IsReady (SomeData)

Because it more clearly demonstrates what will happen once this returns true.

answered Sep 03 '09 at 00:32

Noon Silk

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score 3 · Answer 8 · answered Jul 08 '16 at 07:38

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In Naming conventions, it is written that method name should be verb

answered Jul 08 '16 at 07:38

user2679146

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score 2 · Answer 9 · answered Sep 03 '09 at 00:29

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if you are doing more checks and isRetrievable() isn't appropriate you could use:

IsValid()

answered Sep 03 '09 at 00:29

davidsleeps

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score 1 · Answer 10 · answered Sep 03 '09 at 00:29

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CanRetrieve sounds fine to me. I've seen the Can stem used in Microsoft APIs. The only other real option IMO is IsRetrievable (from Aziz) which somehow seems too linguistically twisted!

answered Sep 03 '09 at 00:29

spender

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score 1 · Answer 11 · answered Sep 03 '09 at 00:29

1

I would prefer isOKToRetrieve or isRetrieveOK over variants without "is" under the convention that functions and methods should be verbs.

answered Sep 03 '09 at 00:29

Tyler McHenry

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score 0 · Answer 12 · answered Feb 25 '16 at 22:45

0

MayRetrieve() could be a better name if the result is determined by the user's permission/access.

IsRetrievable() is more ambiguous, which may be more appropriate if there are other considerations in addition to, or other than, permission.

answered Feb 25 '16 at 22:45

Billy

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Naming Conventions: What to name a method that returns a boolean?

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