Re: [Discuss-gnuradio] IIR Filter taps

[Tom Rondeau]

On Mon, Nov 19, 2012 at 2:40 PM, Tom Rondeau <address@hidden> wrote:
> On Mon, Nov 19, 2012 at 1:57 PM, Johnathan Corgan
> <address@hidden> wrote:
>> On Mon, Nov 19, 2012 at 9:22 AM, Ed Criscuolo <address@hidden>
>> wrote:
>>
>>>
>>> I agree that changing the way gr_iir_filter takes in the taps could
>>> be disruptive, unless backward compatibility is maintained. Some of
>>> the group are using GnuRadio for operational systems.
>>
>>
>> Yes.
>>
>>>
>>> Here's two more suggestions for solutions:
>>>
>>> 1.  Add an optional flag parameter to the constructor, with values
>>>     of "Old_API" and "New_API",  with the default set to "Old_API".
>>>     This flag would control how gr_iif_filter interprets the taps.
>>>     It could be maintained this way for some time, with the Old_API
>>>     being deprecated, and eventually change the default to
>>>     New_API, or even make the default a cmake option.
>>>
>>> 2. Create two subclasses of filter taps that are identical in
>>>    format, and use C++ overloading to determine which constructor
>>>    or set method to use.
>>
>>
>> I think the first is most straightfoward and consistent with how we've make
>> API changes in the past.
>>
>> Johnathan
>
> Agreed. That's a pretty sane way of helping make the transition. An
> argument to the constructor should make people perk up and pay
> attention to the fact that there is a change.
>
> Tom

I just pushed a branch to my github repo called iir_filter that
implements the optional argument to the IIR filter as we discussed.
The default is oldstyle=True and doesn't change any behavior. If you
set this to False, you can directly copy taps from programs like
gr_filter_design (the new version not yet integrated into GNU Radio).

Comments, questions, etc.? If no one sees a problem with this, I'll
merge it into next.

Tom