How to detect if an array if dynamic or static

[sigod via Digitalmars-d-learn]

On Thursday, 25 February 2016 at 12:18:07 UTC, mahdi wrote:
> On Thursday, 25 February 2016 at 11:50:02 UTC, sigod wrote:
>> On Thursday, 25 February 2016 at 10:03:08 UTC, mahdi wrote:
>>> Thanks.
>>>
>>> So when we define the function, we MUST specify the array 
>>> size to be able to accept a static array?
>>> Can't we just define a function which can accept any static 
>>> array with any size? (e.g. a function to calculate average of 
>>> a static int array of any size)?
>>
>> Static array can be accepted in place of dynamic:
>>
>> 	void foo()
>> 	{
>> 		int[3] arr = [1, 2, 3];
>> 		
>> 		bar(arr);
>> 	}
>> 	
>> 	void bar(scope int[] arr)
>> 	{
>> 		import std.stdio : writeln;
>> 		writeln(arr); // [1, 2, 3]
>> 	}
>>
>> But be careful not to escape such variables. Demonstration: 
>> http://dpaste.dzfl.pl/613e04d4fe3f
>
> My question: If in your `bar` function, the code tries to add a 
> new element to the dynamic array, it will be completely ok 
> because array is dynamic. BUT if we pass a static array to this 
> function, can this error be detected at compile time (and 
> prevent a runtime error)? If so, how?

I'm not sure if this is an error at all. Append sees that array 
doesn't have any available space and allocates new array.

	writeln(arr.ptr); // 7FBFC45AA0
	arr ~= 1;
	writeln(arr.ptr); // 4002E000

I would say that you have poor code design if your function must 
be able to accept static arrays and append elements to it.

You might find this useful: 
http://dlang.org/phobos/std_array.html#.Appender