Re: [TCLCORE] TIP 282 status

[Peter S <pet...@gm...>]

On 14/02/2017, avl <av...@lo...> wrote:
>
> Apart from current state of tip-282 (with quoting var- and array-
> names, or using results of sub-expressions as names), it's the only
> other way to also support array-element-assignments.
>

Is quoting that bad?

	expr {
		"arr(sin)" = sin($x);
		"arr(cos)" = cos($x);
		"arr(tan)" = tan($x)
	}

	expr {
		{arr(sin)} = sin($x);
		{arr(cos)} = cos($x);
		{arr(tan)} = tan($x)
	}
	
Probably still better than:

	set arr(sin) [expr {sin($x)}]
	set arr(cos) [expr {cos($x)}]
	set arr(tan) [expr {tan($x)}]

Also possible:

	expr {
		s = sin($x);
		c = cos($x);
		t = tan($x)
	}
	lassign [list $s $c $t] arr(sin) arr(cos) arr(tan)

	lassign [expr {
		list (sin($x), cos($x), tan($x))
	}] arr(sin) arr(cos) arr(tan)

Technically, it's possible to create helper functions that return a
name of an array variable, but that's not any better than quoting the
array name...

	proc array {name index} {
		return "$name\($index)"
	}
	interp alias {} tcl::mathfunc::array {} ::array
	expr {
		[array arr sin] = sin($x);
		[array arr cos] = cos($x);
		[array arr tan] = tan($x)
	}

I'd rather choose simply quoting the variable.

During experimenting with this, I get a weird error that I don't understand:

    % proc array {name index} {return "$name\($index)"}
    % set [array foo bar] 1
    1
    % parray foo
    can't use non-numeric string as operand of "!"
    % set ::errorInfo
    can't use non-numeric string as operand of "!"
        while executing
    "if {![array size UnknownPending]} {
                unset UnknownPending
            }"
        (procedure "::unknown" line 37)
        invoked from within
    "parray foo"
    % set [array foo baz] 2
    2
    % parray foo
    can't use non-numeric string as operand of "!"
    % set ::errorInfo
    can't use non-numeric string as operand of "!"
        while executing
    "if {![array exists array]} {
            return -code error "\"$a\" isn't an array"
        }"
        (procedure "parray" line 3)
        invoked from within
    "parray foo"
    % puts $foo(bar)
    1
    % puts $foo(baz)
    2

I totally don't understand this error.