Modify Function Pointer to Take Additional Parameters

[Yuxuan Shui via Digitalmars-d-learn]

On Friday, 19 February 2016 at 20:45:23 UTC, jmh530 wrote:
> On Friday, 19 February 2016 at 15:00:51 UTC, jmh530 wrote:
>>
>> This works.
>>
>> But when I re-write foo to take that into account as in below, 
>> I get an error that I can't implicitly convert int 
>> function(int x) to int function(int x, int y).
>
>
> I don't think I had looked at what you had done carefully 
> enough. Basically, you just define a new function and take a 
> function pointer of that. That might be a brute force solution.
>
> I tried to use a cast (below) to modify the function pointer, 
> but it is printing the second number instead of the first. I 
> find this behavior strange...
>
> int foo(int x)
> {
> 	return x;
> }
>
> void main()
> {
> 	import std.stdio : writeln;
>
> 	auto foo_ = cast(int function(int x, int y)) &foo;
> 	
> 	writeln(foo_(1, 200)); //prints 200
> }

I don't think it's safe to convert between function pointer with 
different number of arguments... It's possible to mess up the 
stack frame.

Also '(int x, int y)=>f(x)' is clearly a delegate because it 
refers to local variable 'f', you can't just cast it to 'int 
function(int, int)'.