RE: [sv-ec] "this" as default argument

I believe the answer to your question has to be yes, but the LRM does
not support that answer. 'this' is not defined in the scope containing
the declaration of the method. That rule was created to keep you from
doing things like:

function void foo(int A=x, int B=A);
   int x = bar();
endfunction

The rules for determining the order of evaluation would be too complex
at the very least. However, if you have:

class A;

int x;
function void foo(int x=x);
...
endfunction

It's semantically clear that the x on the RHS refers to this.x,
regardless of what identifier is on the LHS because the RHS is evaluated
in the context of the scope containing the declaration of foo, not
inside of foo.

There is an erratum somewhere here.


Dave


> -----Original Message-----
> From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of
> Michael Burns
> Sent: Thursday, March 30, 2006 3:53 PM
> To: sv-ec@eda.org
> Subject: [sv-ec] "this" as default argument
> 
> 
> Hi folks,
> 
> Is it the intent of the committee that "this" should be a valid
default
> argument value for class methods? For example,
> 
> class Foo;
> ...
> 
>   task mytask(Foo f = this);
>      ...
>   endtask
> endclass
> 
> The 1800 standard seems to suggest this (12.4.3, "The default_value is
> an expression. The expression is evaluated in the scope containing the
> subroutine declaration each time a call using the default is made"),
but
> section 7.10 makes it a little less clear ("The this keyword shall
only
> be used within nonstatic class methods") - does use as a default value
> in the method's arg list count as being "within" the method?
> 
> --Mike Burns
> Freescale Semiconductor