Variable argument count?

[Loriel]

How do I pass all or some of my however many arguments to another function taking a variable amount of arguments?

As in lua's function foo(x, y, ...) something_with(x, y) bar(...) end, I guess.

[Crow]

Uhhh...could probably use the params[] array.

[Loriel]

Originally Posted by Crow

Uhhh...could probably use the params[] array.

How do I use the params array?

[Crow]

Originally Posted by Loriel

How do I use the params array?

Well, it's an array that stores the arguments. Example:

PHP Code:

function myFunc(arg1, arg2, arg3) {
  echo(params[0]);
  echo(params[1]);
  echo(params[2]);
} 


Would echo arg1, arg2 and arg3 in that order. So you could probably check the size of that array, do some magic, and then pass the arguments to another function.

[Loriel]

Originally Posted by Crow

Would echo arg1, arg2 and arg3 in that order. So you could probably check the size of that array, do some magic, and then pass the arguments to another function.

Could you elaborate on the magic?

Edit: Uh, how do I even call that function to make params[0] actually hold a value?

[Crow]

Originally Posted by Loriel

Could you elaborate on the magic?

No idea what one could do in this case. Though, since this is still Graal, using that array is probably the only way to go. I don't have an idea how exactly you could do this though.

[Programmer]

Originally Posted by Loriel

Could you elaborate on the magic?

Edit: Uh, how do I even call that function to make params[0] actually hold a value?

params[] is set to the total sum of the variables passed into a function. Consider the following:

PHP Code:

function Foo(bar, baz)
{ ... }

Foo(1, 2, true, 999); 


bar would equal 1, and baz would equal 2. However, the params array looks like this:

PHP Code:

{1, 2, true, 999} 


And thus, the above function can literally be transcribed into:

PHP Code:

function Foo()
{
    bar = params[0];
    baz = params[1];
} 


This is not dissimilar to C#'s implementation of parameters, if you're into that:

PHP Code:

// C#
private void Foo(params object[] parameters)
{
     var bar = parameters[0];
     var baz = parameters[1];
} 


[Loriel]

Originally Posted by Programmer

params[] is set to the total sum of the variables passed into a function. Consider the following:

PHP Code:

function Foo(bar, baz)
{ ... }

Foo(1, 2, true, 999); 


I cannot quite get this to work. I inserted echoo({bar, baz}); into the function body for testing. Indeed it outputs 1,2 as I expected.

And thus, the above function can literally be transcribed into:

PHP Code:

function Foo()
{
    bar = params[0];
    baz = params[1];
} 


Now when I do this, the output is "",0. If I say echo(params), I do not get any output at all. Am I missing something here?

This is not dissimilar to C#'s implementation of parameters, if you're into that:

PHP Code:

// C#
private void Foo(params object[] parameters)
{
     var bar = parameters[0];
     var baz = parameters[1];
} 


I think it is indeed dissimilar, because I could call that function with a single array instead of a list of parameters.

[Programmer]

Originally Posted by Loriel

I cannot quite get this to work. I inserted echoo({bar, baz}); into the function body for testing. Indeed it outputs 1,2 as I expected.

Try:

PHP Code:

function Foo(bar, baz)
{
    echo({ bar, baz });
    echo(params);
}

Foo(1, 2, true, 999); 


Will echo:

1, 2
-- Comment: 'true' is represented as 1.
1, 2, 1, 999

Originally Posted by Loriel

Now when I do this, the output is "",0. If I say echo(params), I do not get any output at all. Am I missing something here?

0 in Graal is literally translated as 'null', and will print absolutely nothing to the RC. An empty string literal will obviously print nothing as well.

Originally Posted by Loriel

I think it is indeed dissimilar, because I could call that function with a single array instead of a list of parameters.

In C#, it's similar in this manner:

PHP Code:

// C#
private void Foo(params object[] parameters)
{
     var bar = parameters[0];
     var baz = parameters[1];
     
     Console.WriteLine("Result: " + bar + ", " + baz);
}

Foo(1, 2);

// OUTPUT:
// Result: 1, 2 


[cbk1994]

I've had some problems where the params[] array is erased/non-existent if you assign variables to the parameters in the function.

[Admins]

The params[] array is only created when the script is called (doesn't even need to be a function, GS1 style). That is either on an event, or when you call a function of another object. To get a variable number of parameters either use func(arg1, arg2, arg3, arg4 etc) and ignore the arguments that you don't want, or pass the parameters as array.

Currently accessing the parameters for each function as array is not possible because it would mean a big speed slowdown, although if it's really important to have it then we could add something like temp.functionparams[] which dynamically converts the function parameters to variables.

[Loriel]

Originally Posted by Stefan

The params[] array is only created when the script is called (doesn't even need to be a function, GS1 style). That is either on an event, or when you call a function of another object. To get a variable number of parameters either use func(arg1, arg2, arg3, arg4 etc) and ignore the arguments that you don't want, or pass the parameters as array.

Thanks, that clears it up. Some experimentation suggested the FAQ thread was inaccurate about this and some dude on IRC said it only worked for triggers, so that makes sense.

Currently accessing the parameters for each function as array is not possible because it would mean a big speed slowdown, although if it's really important to have it then we could add something like temp.functionparams[] which dynamically converts the function parameters to variables.

Not important, I really just wanted to build an error reporting function that would forward all its arguments to format() and print the resulting string with more error stuff, instead of having the user call format, and consequently got confused about how variadic functions even work.