How to build a library as client of Arduino-IRremote?

[jblinka]

I'm helping someone with an Arduino project that incorporates several devices. One of the input devices is an IR remote. I'm attempting to build a library for that project. Part of the library makes use of an IRrecv. I have run into what seems like an unending series of linker problems of the multiple definition or undefined reference variety, depending on the code experiments I've run.

I have read "Using the new *.hpp files" section of https://github.com/Arduino-IRremote/Arduino-IRremote#does-not-workcompile-with-another-library and have spent considerable time studying the source code. My understanding is that USE_IRREMOTE_HPP_AS_PLAIN_INCLUDE separates the declaration from the definition of class IRrecv and the instantiation of IrReceiver. If you define USE_IRREMOTE_HPP_AS_PLAIN_INCLUDE, you get only the declaration. If undefined, you get declaration, definition and instantiation of IrReceiver. Define USE_IRREMOTE_HPP_AS_PLAIN_INCLUDE when you're writing library code that only needs the declaration. Don't define it in a .ino when you need both the declaration and the definition in order to compile and link.

At least that's my impression. Could well be wrong!

But I can't seem to build a .ino successfully due to linking problems.

Here's the closest I've gotten:

/examples/link/link.ino:

#define INCLUDE_FROM_INO
#include "vscope.h"

simple S;

void setup() {
}

void loop() {
S.read(); // links if this is commented out
}

/src/vscope.h:
#include "simple.h"

/src/simple.h:
#ifndef INCLUDE_FROM_INO
#define USE_IRREMOTE_HPP_AS_PLAIN_INCLUDE
#endif
#include <IRremote.hpp>

class simple {
public:
simple();
void read();
private:
IRrecv _rcvr;
};

/src/simple.cpp:
#include "simple.h"

simple::simple() {}

void simple::read() {
_rcvr.decode((void*)0); // won't work!, 0 just keeps compiler happy for this compile/link test
}

Short Explanation:
My library "vscope" supports a device that uses an IRrecv as a client through class "simple". "simple" has a read operation, which uses its internal IRrecv to read IR remote input. The presence/absence of the token INCLUDE_FROM_INO turns USE_IRREMOTE_HPP_AS_PLAIN_INCLUDE off/on in sketch/ino code vs library code. I think that's what "Using the new *.hpp files" tells me to do.

This compiles, but linking fails with message "undefined reference to `_ZN6IRrecv6decodeEP14decode_results'", and a reference to the _rcvr.decode() statement in simple::read().

I'm using Arduino IDE-1.8.19 on a Gentoo linux system, programming for an Arduino nano. My development environment otherwise produces working code for the nano, and the IRremote example SimpleReceiver works fine.

So... what am I misunderstanding/doing wrong? Is it possible for a library to use an IRrecv as a client?

Thanks for your help!

John Blinka

[ArminJo]

At least that's my impression. Could well be wrong!

No, you are right! 😀

But please, do not use deprecated functions, use _rcvr.decode();
I extended the IRremoteExtensionClass example. to cover your problem and I get no errors.

[jblinka]

Sent from Proton Mail for iOS On Tue, Aug 15, 2023 at 4:25 AM, Armin ***@***.***(mailto:On Tue, Aug 15, 2023 at 4:25 AM, Armin <<a href=)> wrote

But please, do not use deprecated functions, use _rcvr.decode(); I extended the [IRremoteExtensionClass](https://github.com/Arduino-IRremote/Arduino-IRremote/blob/master/examples/IRremoteExtensionTest/IRremoteExtensionClass.cpp) example. to cover your problem and I get no errors. —

With your guidance, my library works perfectly now. I don’t know how I came to use the interface I posted, but it was older code that had worked previously. I’ve looked at examples/SimpleReceiver in more detail just now and see how to do it properly. Thank you! John