pinMode() in class constructor? seem not to work

[Coding_Badly]

Arduino Sketches | Arduino Documentation

The setup() is called once, when the sketch starts. It's a good place to do setup tasks like setting pin modes or initializing libraries.

There are copious places where that is affirmed. Enough to justify my claim that it's a contract.

@jasonacox

Most libraries I use were built the way the tutorial outlines.

Bear in mind that tutorial is older than this thread and has not been subjected to peer review (until now). It needs to be updated.

@jasonacox

I'm wondering, instead of changing all of the libraries to accommodate, could we instead address how Arduino supports global declarations that initialize hardware?

There is. It has a high price.

@jasonacox

Calls made in a constructor that invoke Arduino functions or make hardware calls like pinMode() that need the main init() could trigger init() themselves.

That would be a breaking change. The overhead of checking for initialization would interfere with existing code that requires low(-ish) latency.

@jasonacox

...the spirit of the Arduino project...

Serial.begin
Wire.begin
SPI.begin
Notecard.begin
LiquidCrystal_I2C .begin
WiFi.begin
The MIDI Device has a begin.
et cetera

The spirit of Arduino is to include a begin meant to be called in setup.