Io language 'apply arguments'

问题

In the Io programming language, is there an equivalent to lisp's apply function.

So for example I have a method to wrap writeln :

mymeth := method(
              //do some extra stuff

             writeln(call message arguments))
)

At the moment this just prints the list, and doesn't evaluate it's contents as if they were it's own args.

回答1:

Thanks to that person who suggested evalArgs (not sure where your comment went).

Anyway that has resolved for my situation, although unfortunately not in general I guess.

You can achieve what I describe by doing :

writeln(call evalArgs join)

This evaluates all arguments, and then joins the results into a single string.

回答2:

is there an equivalent to lisp's apply function?

Have a look at perform & performWithArgList methods.

To step back a bit you can replicate Lisp's FUNCALL in a few different ways in Io:

1 - Passing a function ie. block():

plotf := method (fn, min, max, step,
    for (i, min, max, step,
        fn call(i) roundDown repeat(write("*"))
        writeln
    )
)

plotf( block(n, n exp), 0, 4, 1/2 )

2 - Passing a message:

plotm := method (msg, min, max, step,
    for (i, min, max, step,
        i doMessage(msg) roundDown repeat(write("*"))
        writeln
    )
)

plotm( message(exp), 0, 4, 1/2 )

3 - passing the function name as a string:

plots := method (str, min, max, step,
    for (i, min, max, step,
        i perform(str) roundDown repeat(write("*"))
        writeln
    )
)

plots( "exp", 0, 4, 1/2 )

So from all this you could create a Lisp APPLY like so:

apply := method (
    args := call message argsEvaluatedIn(call sender)
    fn   := args removeFirst
    performWithArgList( fn, args )
)

apply( "plotf", block(n, n exp), 0, 4, 1/2 )

apply( "plotm", message(exp), 0, 4, 1/2 )

apply( "plots", "exp", 0, 4, 1/2 )

来源：https://stackoverflow.com/questions/4419779/io-language-apply-arguments

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