Avoid conflicts with similar declaration of MAX_SOCK_NUM

[PaulStoffregen]

Why is this needed? What other code is conflicting?

Ethernet has exposed this define since the earliest days of Arduino, since at least 2008 (long before Arduino was using github).

[agdl]

@PaulStoffregen using for example MKRWiFi1010 + MKR ETH Shield. I already Changed the WiFi NINA here https://github.com/arduino-libraries/WiFiNINA/commit/00c9caacb2f6e4df94c26a8c393ad60824b5a4f1 so this isn't really necessary, but will be nice to align the defines names. That's it!

[Rotzbua]

A perfect example why namespaces were introduced into programming :wink:

[PaulStoffregen]

If this is changed, I believe the proper approach would be the bring it inside EthernetClass, rather than keeping it as a preprocessor macro. I had considered doing this for version 2.0.0, but I intentionally left things the way they were...

The main question I have is whether we should keep MAX_SOCK_NUM defined for backwards compatibility? That is the reason I left it in 2.0.0. Removing MAX_SOCK_NUM from newer libs is much easier. Ethernet has exposed this define to Arduino sketches and libraries for at least 10 years. Many people have used it.

[PaulStoffregen]

For example, here are several Arduino sketches where users have relied on MAX_SOCK_NUM.

https://github.com/seth1993/Spectro/blob/f744c7b05c09474544b4081920633bbafd870c80/ArduinoTempSensor/libraries/bitlash/examples/ethernetcommander/ethernetcommander.ino#L144

https://github.com/kmpelectronics/Arduino/blob/ea8d03cec359f7b185883314fb34827543bf366e/KMPDinoEthernet/src/KMPDinoEthernet/examples/projects/ProDinoIntRelay/ProDinoIntRelay.ino#L136

https://github.com/neophob/SkyInvaders/blob/master/Arduino/SkyInvaders/WOL.ino#L42

https://github.com/mistergreen/WAAC/blob/9efd403f7a2be7a58f8450c78f2915c47cda58b8/Arduino_Due/WAAC_ethernet_1.8.1/WAAC_ethernet_1.8.1.ino#L913

https://github.com/seth1993/Spectro/blob/f744c7b05c09474544b4081920633bbafd870c80/ArduinoTempSensor/libraries/bitlash/examples/BitlashWebServer/BitlashWebServer.ino#L283

https://github.com/omidomidi/Smart-Home/blob/64f4d619bf23eb6b37e4a8c95e3d1af8d8d7e0f7/Humidity_Temperature_Sensor/examples/CC3200_WeatherWebServer/CC3200_WeatherWebServer.ino#L321

Several of these, specially Bill Roy's code, have been very widely copied into many people's projects. If we remove or rename MAX_SOCK_NUM, we will almost certainly break all of these programs!

[Rotzbua]

I think with version 2.0.0 MAX_SOCK_NUM is not fully backwards compatible. Because MAX_SOCK_NUM is defined at compile time. If it enough ram is available, it is set to 8. But if a w5100 is found at runtime, it is wrong because a w5100 only support 4 sockets.

https://github.com/arduino-libraries/Ethernet/blob/6e9dffa64f6b0eb89607dbb5293dc33be82cc39e/src/Ethernet.h#L36-L40

BTW The pr is incomplete. The definition of MAX_SOCK_NUM is not renamed.

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