Re: [Discuss-gnuradio] Q's on gr-filter (was: Developers' Call for June, 2012)

[Martin Braun (CEL)]

Hi Johnathan,

and thanks for the answers!

On Fri, Jun 22, 2012 at 09:15:53AM -0700, Johnathan Corgan wrote:
>     - Can you please comment on making *all* blocks virtual and totally
>      separating the DSP from the block definition? Is this simply taking the
>      separation to a new 'extreme', or are there other reasons? Is it still
>      possible to make the block non-virtual and put everything inside?
> 
> I don't quite follow your question.  Could you elaborate?

Sure: in the old system, the actual blocks are directly derived from
gr_block (or gr_sync_block etc.). Now, only virtual blocks are derived
from gr_block (and exported). Then, in 'lib', the virtual blocks are
further derived into the impl-blocks, where the DSP is done.

This comes with a slight cost in overhead: (e.g., extra .h-files, and
any methods which are exported need to be declared first virtual, then
derived and defined).
My questions are
1) Where are the benefits of this approach? (The simple three-line swig
   files seemed to work without the additional abstract blocks)
2) If I don't like this method, does anything stop me from making the
   block derived directly from gr_block non-virtual and putting the DSP
   inside that block (I assume at the very least I have to use the old
   SWIG_MAGIC function?)

>     - By which logic is mmse_fir_interpolator_cc.cc not a '_impl.cc' file?
> 
> It's not actually a block, and the header isn't exported.  It is code used
> internally by the fractional_interporlator_cc and _ff blocks, which *are*
> impled.

Obviously I misunderstood the usage of the _impls: I assumed anything
that wouldn't necessarily have to be put inside a block would be an
impl.

Cheers
MB


-- 
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)

Dipl.-Ing. Martin Braun
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