Some MACRO tidbits

@zander

More of a niggle than a criticism, but I think you'd be better off using something like

#define BETWEEN(NUM,LOW,HIGH)    ((NUM>=LOW) && (NUM<=HIGH))

Reasons ...

1) all three values specified

2) no need to create an pointless struct

3) independent of struct component names

4) equivalent form is BETWEEN(37,Q1.Start,Q1.End)

@will Excellent point Master Will. I was addressing a specific use case, and should have mentioned the BETWEEN macro was not generic. More like a set operator really. I will steal thay (with your permission of course) and back fit it into my use case, that way it's a win win. Thanks buddy.

@zander

Posted by: @zander

I was working an issue earlier today and saw the need for a macro or two. I also have not seen many or maybe any macros being used on the forum so maybe some of the newer members are unfamiliar with them, I am sure all the old boys like me are very familiar. I also have a feeling my C++ friends will show me how they can do it better. The first macro is a simple "is this number between two other numbers" while the second is just a test/debug print statement I didn't feel like copy/paste/editing so I made a macro instead. Let me know if you have questions, corrections, improvements (especially the comparison, I think it can be better)

[snipped example code]

Your macros look ok to me, but... their use is frowned upon these days, and there are better or cleaner ways to achieve the same result.

A few good reasons not to use them may include:
  Ugly and hard to read as they get bigger
  They do not have a namespace, and as such they do not have any scope, and can break code easily
  Very difficult to debug as they are a simple text replacement by the preprocessor

I don't see anything wrong with using a struct or class as you have, but if you're just going to use it the way you've shown, then there is a better way to implement your desired functionality using one

I'll cobble up as an alternative for you shortly...

Cheers

@frogandtoad I actually agree with you re all the reasons macros are not a good idea, and I see that Arduino recommends against them also. Since I was still seeing a vast majority of folks and examples using #define vs const I assumed anarchy still ruled the IT world. It sounds like there may be hope.

My path to the macros was very random and I was trying to work out a way to simplify a specific coding problem but then tried to turn it into a generic solution. My BAD.

As to your solution, as you may remember I do not understand C++ so the syntax looks very weird to me. I am going to make a guess that the statement below is doing dual duty, one as a constructor and one as a member thingy??? Don't get me wrong, I like terse language in many cases especially now that my old brain has such a small cache size. The second question is that 0 is NOT between 1 and 101 so where is the message or error or something, is there yet another C++ feature I am not knowing about?

isBetween(1, 101).number(0);

Posted by: @zander

@frogandtoad I actually agree with you re all the reasons macros are not a good idea, and I see that Arduino recommends against them also. Since I was still seeing a vast majority of folks and examples using #define vs const I assumed anarchy still ruled the IT world. It sounds like there may be hope.

My path to the macros was very random and I was trying to work out a way to simplify a specific coding problem but then tried to turn it into a generic solution. My BAD.

As to your solution, as you may remember I do not understand C++ so the syntax looks very weird to me. I am going to make a guess that the statement below is doing dual duty, one as a constructor and one as a member thingy??? Don't get me wrong, I like terse language in many cases especially now that my old brain has such a small cache size. The second question is that 0 is NOT between 1 and 101 so where is the message or error or something, is there yet another C++ feature I am not knowing about?

isBetween(1, 101).number(0);

I'll try to explain the best I can.

Firstly, "isBetween" as a struct (and is also considered a class in C++), and "number(num)" is a member function of that class.

I created a custom constructor "isBetween(min, max)" to accept the two values for flexibility of use.

Calling "isBetween(1, 101)" creates a "temporary" object, so rather than creating a persistent object:

    isBetween rangeObject(1, 101);

... and then calling the member function upon it:

    rangeObject.number(0);

... it's easier to just use the temporary object and call the member function directly upon it:

    isBetween(min, max).number(num_to_check);

Does that make sense?

In essence, I'm using a class as a better function.

As for your second question, the number function has a default parameter, thats why I demonstrated both versions... if you add "true" for the third parameter, you should see the message 😉

Cheers

@frogandtoad I could use a lesson. I see nMin and nMax used 3 or 4 times and I suspect they are not really the same thing. Could you re-do that code snippet with each variable in a different namespace using a different name so I get a better sense of what is happening.

Also why does the entire thing start with struct, I see no pieces as in my example.

Posted by: @frogandtoad

Posted by: @zander

@frogandtoad I actually agree with you re all the reasons macros are not a good idea, and I see that Arduino recommends against them also. Since I was still seeing a vast majority of folks and examples using #define vs const I assumed anarchy still ruled the IT world. It sounds like there may be hope.

My path to the macros was very random and I was trying to work out a way to simplify a specific coding problem but then tried to turn it into a generic solution. My BAD.

As to your solution, as you may remember I do not understand C++ so the syntax looks very weird to me. I am going to make a guess that the statement below is doing dual duty, one as a constructor and one as a member thingy??? Don't get me wrong, I like terse language in many cases especially now that my old brain has such a small cache size. The second question is that 0 is NOT between 1 and 101 so where is the message or error or something, is there yet another C++ feature I am not knowing about?

isBetween(1, 101).number(0);

I'll try to explain the best I can.

Firstly, "isBetween" as a struct (and is also considered a class in C++), and "number(num)" is a member function of that class.

I created a custom constructor "isBetween(min, max)" to accept the two values for flexibility of use.

Calling "isBetween(1, 101)" creates a "temporary" object, so rather than creating a persistent object:

    isBetween rangeObject(1, 101);

... and then calling the member function upon it:

    rangeObject.number(0);

... it's easier to just use the temporary object and call the member function directly upon it:

    isBetween(min, max).number(num_to_check);

Does that make sense?

In essence, I'm using a class as a better function.

As for your second question, the number function has a default parameter, thats why I demonstrated both versions... if you add "true" for the third parameter, you should see the message 😉

Cheers

GOT IT, thanks. However not enough to start writing it, just need to understand enough to read it. 

@frogandtoad Thanks, that helps. I will study that. In case I have not mentioned it, muy brain was injured at birth so now I often don't remember proper names of things like struct pieces? as in name, address etc. Maybe struct fields?

@zander

Posted by: @zander

@frogandtoad Thanks, that helps. I will study that. In case I have not mentioned it, muy brain was injured at birth so now I often don't remember proper names of things like struct pieces? as in name, address etc. Maybe struct fields?

No worries.

In C++ terminology, class variables are referred to as "data members" or "member data" when generalising. Likewise, functions are called "member functions".

Cheers

@frogandtoad Ok, got it, for now LOL.

@zander 

Forgot to mention yesterday, with respect to how macros don't respect namespaces and have no scope.  This was actually a classic example of why to avoid macros if you can!

Initially, I wanted to name my class variables 'min ' and 'max' for my example, but look what happened:

Because Arduino.h is implicitly included in every sketch, it also implicitly includes the macros 'min' and 'max' via other header files. Even if I wrap my own code with a namespace, the macros will still not respect them... so I was forced to use 'nMin' and 'nMax' to my disliking - This is how code is easily broken by using macros, as they are now always in scope when you don't want them to be, polluting the global namespace.

Cheers

@frogandtoad EXCELLENT example. 

My profuse apologies for my (hopefully) brief wanderings in the land of frankenstein code. At least I hope my transgressions were educational. Now if everyone would stop using them (including #define) then life would be easier for those of us who spend a lot of time trying to fix others code.