[Halld-offline] [Fwd: CLEO coding standard]

[Matthew Shepherd]

Hi Richard,

I think every class should *declare* a default constructor.  As you  
point out, for some classes it is not appropriate to have a default  
constructor.  In this case the default constructor should be declared  
private (as the rule states).  If you don't declare a default  
constructor then the compiler can auto-generate one, which can lead to  
problems for certain classes.

The issue here may be correctly interpreting the word "declare" which  
means "explicitly written in the header file" (to prevent auto- 
generation).  It does not imply the constructor is defined or public.

-Matt


On Sep 17, 2009, at 3:06 PM, Richard Jones wrote:

> Response to proposed coding standard:
> 	• All classes should declare a copy constructor, an assignment  
> operator from its own type, a default constructor and a destructor.  
> Any that are not used should be declared private and not defined.
> Comment: I suggest a change from "a default constructor and a  
> destructor" to "at least one constructor and destructor".  It is not  
> always appropriate to have a default constructor, and default  
> constructors are only automatically generated if there are no non- 
> trivial constructors defined.  This rule does not state whether they  
> must be public or not.  There are cases such as friend factory  
> classes where having no public constructors actually makes the most  
> sense.  But regardless, there should not be a rule that says every  
> class must have a default constructor.  Even though it is possible,  
> it suggest semantics to the user of the class that may actually not  
> make any sense.
> 	• All classes which might possibly be used as base classes must  
> define a virtual destructor.
> I think modern compilers flag this as an error.  If so, we don't  
> need a rule about it.
>
> -Richard Jones
>
>
>
>
> Mark M. Ito wrote:
>>
>> Folks,
>>
>> Matt Shepherd sent this to me last week. I think it serves as an  
>> example
>> of what we might want to adopt for a coding standard and can serve  
>> as a
>> starting point for a discussion. Read it over and send out your  
>> comments
>> to the list or to me if so moved. We will discuss the idea of  
>> standards
>> at a future Offline meeting, of course.
>>
>>   -- Mark
>>
>>
>>
>
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