RE: [sv-ec] disable class method

>From: "danielm" <danielm@aldec.com.pl>

>>I would also assume that you could reference without an object, 
>>with something like "disable C::t", even for a task that is not a static
>method. 
>
>LRM clearly defines that you can refernce by "::" operator only to static
>properties and static methods. It should be explicitly defined in LRM if
>there are any exeptions

You have a valid point.  I was not considering the actual wording of the
restriction in the LRM.  I was considering the reason for the restriction,
which does not apply here, and therefore assuming that the restriction did
not apply.

But if we are going strictly by what the LRM says, then I don't think you
can disable a non-static method at all.  The disable statement takes a
hierarchical path.  I don't believe that a class-select qualifies as a
hierarchical path.  If that is true, then you cannot use a class-select
as the target of a disable.

I guess you could still disable a non-static method from inside any
non-static method of the class.  From there it is legal to reference a
non-static method, and the reference is not explicitly a class-select.
Normally a reference is allowed because it is implicitly using the same
object as the current method, i.e. it is an implicit class reference.
In the case of a disable, no object is needed.  So the fact that a
disable can only be performed from there is an artificial restriction.

For a static method, it could be debated whether C::t is considered to
be a hierarchical name of a task.  If so, then static methods can be
disabled that way.  Otherwise they could only be disabled from inside
the class.  I don't see any reason why C::t would not be considered a
hierarchical name of a task for this purpose.


>> The actual type of the object might determine which implementation of the
>task would get disabled (i.e. the task declared in which base class).  
>> This is so strange that I would support making it illegal.
>
>If so then this also should be explicitly defined by LRM

If you accept my argument that class-selects cannot be the target of a
disable, then there is no way to specify an object to select a virtual
method implementation.  You could only specify a particular static method
in a particular class.

This would be a little strange for a disable of a virtual method from
inside a class method.  If this were a call to the virtual method, then
the 'this' object would determine which implementation is called.  But
a disable of the method is not a reference through a class object.  It
is a static hierarchical path.  As such, it would always refer to the
implementation in the same class definition where the disable appears.
This is somewhat irregular.

Steven Sharp
sharp@cadence.com


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