Re: static class member as interrupt handler works, but not if class is templated

Trampas Stern,

I'm sorry, but I've got to chime in here grasshopper.  David Kelly put 
it well: just "don't use C++"!

I somehow knew that this would start a flame war. :-)

[FLAME ON] We've been there, done that, bought the T-shirt, here in 
forums like this before, going back many decades!  I've heard all your 
silly platitudes repeatedly here and in other places---always coming 
from "wise fools" like yourself.

IMNSHO putting your specious arguments "on the Internet" for all 
posterity to see is not the best move professionally.  When I see 
statements like yours:

/"Note that I have worked on projects in the past where we squeezed 
every clock and every byte out of a processor. However I have not had to 
optimize for size or speed in 10 years.  That is processors are so cheap 
and powerful if you have to optimize code for size or speed then you 
most likely picked the wrong microprocessor."
/

...you are definitely NOT ever going to be working with me.

Why is plain old C still one of the most popular programming 
languages---number 1 by some measures (i.e., 
https://tiobe.com/tiobe-index/)?  It's because commercial embedded 
systems ALWAYS directly benefit from small and fast. If you are a 
hobbyist you can make statements like you did. However us professional C 
programmers that get paid the "big bucks" are in demand precisely 
because they can deliver products that run with minimal compute 
resources on the least expensive microcontrollers possible!

And, yes one can reuse C code---I've been doing it for decades. As for 
interrupt handlers and device drivers, between C macros and 
programmatically generated C code (e.g., Perl scripts) you can have it 
all without the "crutch" of C++ templates and class nonsense. [FLAME OFF!]

BTW: I suggest that you quit while you're ahead---but David and I 
somehow know that you won't! :-)

Best regards,

Bruce D. Lightner
Lightner Engineering
La Jolla, California
[email protected]
https://www.linkedin.com/in/brucedlightner/

------------------------------------------------------------------------
On 4/10/2021 3:36 PM, Trampas Stern wrote:
> Actually C++ is not slower or more bloat than C, depending on the 
> features used.
>
> For example I do not use RTTI or exceptions, so that makes it about 
> the same as C for size. Yes you have to turn these features off in 
> your compiler (-fno-rtti, -fno-exceptions). Sure you have 
> trampolines or jump tables for function overloading but you have to do 
> the same in C. If you do not use inheritance or function 
> overloading you do not have the penalty.
>
> I find that in most of my embedded projects the cost of development 
> time is more than the cost of the processor for 5 years of production, 
> that is the products are not super high volume products.  As such, 
> reducing development time is very important.   To this end I do things 
> like write libraries and test them, and then reuse them.  For example 
> I write an abstract interface class for a CharDevice, and BlockDevice. 
> Then a UART can be a CharDevice and EEPROM a BlockDevice, SDCard is a 
> BlockDevice, etc.  This allows faster development.  Sure I can do this 
> in C, but C++ basically does the same thing I would do in C and is 
> easier to understand.
>
> Also things like templates are valuable, for example I wrote a FIFO 
> template.  I debug that template once and never have to write fifo 
> code again.  This is something very hard to do in C with any 
> efficiency.  Now I can create a FIFO for uint8_t, uint32_t, or a 
> structure with one line.  This can not be done easy in C. The same is 
> true for circular buffers and such...
>
> So yea C++ on embedded is very valid and real.   I have been doing 
> professional embedded C for over 30 years and just switched to C++ and 
> do not want to go back to C.  The misconceptions about bloat are no 
> longer valid.  Sure you can write bad C++ code using standard 
> templates and such but you can also write bad C code, so don't do 
> either. I think the misconception about C++ is because people try to 
> do stupid stuff like use cout, new, RTTI, exceptions, etc.  Where most 
> of the time the simple compile time features of C++ offer huge 
> advantages over C.
>
> At the end of the day all the compile time features of C++ are 
> free, like classes. There is zero reason not to use them because they 
> are free. The run time features are not free but you can choose what 
> you use, and turn off what you don't need.
>
> So yes I can write bad C++ code that is slow and bloated. I can write 
> bad C code that is slow and bloated. My job is to write functional 
> code that works and works correctly with no side effects and I can do 
> that faster and more efficiently in C++ using OO and minimal features 
> of C++.  Maybe others can not, but that is not my problem.
>
> Note that I have worked on projects in the past where we squeezed 
> every clock and every byte out of a processor. However I have not had 
> to optimize for size or speed in 10 years.  That is processors are so 
> cheap and powerful if you have to optimize code for size or speed then 
> you most likely picked the wrong microprocessor.
>
> The problem with interrupt handlers which I asked about still exists 
> if you use C to write the code.  That is you still have to map the 
> interrupt handler to the correct instance of the object unless you are 
> insane and write a driver for each UART instance, which talking about 
> bloat and slow....
>
> Trampas
>
>
>
> On Sat, Apr 10, 2021 at 5:12 PM David Kelly <[email protected] 
> <mailto:[email protected]>> wrote:
>
>     On Apr 10, 2021, at 2:37 PM, Trampas Stern <[email protected]
>     <mailto:[email protected]>> wrote:
>
>>     If you guys have a better way I would love to know.
>
>     Don’t use C++?
>
>     What does object-oriented coding do for embedded projects? It’s
>     akin to using printf(). Slow and lots of bloat.
>
>     Time once was I put uint32 in a union so as to code ++ inline
>     rather than let avr-gcc call a library routine. Even more so if in
>     an interrupt. Not all library routines used to be re-entrant.
>
>     --
>     David Kelly N4HHE, [email protected] <mailto:[email protected]>
>     ============================================================
>     Whom computers would destroy, they must first drive mad.
>


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