ino does not support default values properly.

[jantje]

This may be accepted as a limitation of the system but following code does not compile in the arduino ide 1.5.5 (and I assume all others)

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:
 beep(1);
}

void beep(int numberOfBeeps, boolean shortbeep = false){
//no code here as it is irrelevant
}

[matthijskooijman]

I presume that either the IDE doesn't recognize the beep definition and cannot provide a forward declaration, or it includes the default arguments in the generated forward declaration which causes the compiler to barf. An error message would be helpful :-)

[jantje]

actually the IDE doesn't make a link between the 2 beeps and as such it is a simple "error: ‘beep’ was not declared in this scope"
Even with beep(1,true); there is no link and as such no declaration function generated.
So the same error is generated.
It looks like the ino format simply does not support default values for parameters.
As I don't see a good way to handle these parameter I'd be happy to get confirmed that "when parsing ino files; ignore functions that have default values" is a design decision the arduino core team took.

So basically I think I agree with "I presume that the IDE doesn't recognize the beep definition and cannot provide a forward declaration"

[matthijskooijman]

Ok, the error you're seeing is simply how C++ works: you can only reference functions defined earlier in the file (unless you add a forward declaration). The IDE normally inserts forward declarations automatically as a service to the user, but I suspect that it doesn't recognize the function definition because of the default arguments. I doubt this is a design decision - it's probably just that the regex used isn't extensive enough (and this is, IMHO, exactly why doing this automatic forward declaration and similar stuff in the IDE is a bad idea - you need a proper parser to really be able to cover all cases...)

[jantje]

identification is a problem but I think finding a solution is even harder.
If you forward declare

void beep(int numberOfBeeps, boolean shortbeep = false);

you get an error
if you forward declare

void beep(int numberOfBeeps, boolean shortbeep );

you also get an error
So the only solution I see is
foward declare

void beep(int numberOfBeeps, boolean shortbeep = false);

and modify

void beep(int numberOfBeeps, boolean shortbeep = false){
//no code here as it is irrelevant
}

to

void beep(int numberOfBeeps, boolean shortbeep ){
//no code here as it is irrelevant
}

Not something I would look forward doing.

[matthijskooijman]

Good point - when a forward declaration is present, default arguments should be present only on the forward declaration, not on the definition. I guess this would be wontfix, though this is up to @cmaglie and friends :-)

[jantje]

I assume the arduino core team hit this problem (like I hit it in my plugin today) and decided not to support functions with default parameter values.
I just would like to be sure.

[xaljox]

It is not something the arduino IDE team can do something about. It is in the GCC compiler, the same as eclipse is using. It is more or less a C++ thing. If you allow defualt parameters on the forward declarion AND on the actual implementation you could set them to different values and then it can get tricky as to use wich value. Thus only in the (forward) declaration the default parameters are allowed in C++.
It is to my knowledge not a compiler specific thing, since Visual studio does the same and Xcode as far as I know also. In the past Xcode also used GCC, but they use now another newer compiler.

On 02 Jul 2014, at 22:58, jantje notifications@github.com wrote:

I assume the arduino core team hot this problem (like I hit it in my plugin today) and decided not to support functions with default parameter values.
I just would like to be sure.

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Reply to this email directly or view it on GitHub.

[jantje]

closing as unfixable