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Postings from May 2005
> -----Original Message-----
> From: news [mailto:news@sea.gmane.org] On Behalf Of Ingo Blechschmidt
> Sent: Saturday, May 21, 2005 7:22 AM
> To: perl6-language@perl.org
> Subject: Declaration of my() variables using symbolic referentiation
>
> Hi,
>
> am I correct in the assumption that the following is an error?
> # Not in a BEGIN block
> my $::(calc_varname()) = 42;
>
> I think so, as my() is a compile-time operation, but in this
> example, the variable name is not known until runtime, so I
> think this should be forbidden. Correct?
>
> But:
> BEGIN {
> my $::(calc_varname()) = 42;
> }
> I think this one is ok, as the compiler can invoke
> &calc_varname at compile-time, and therefore know the variable
> name at compile-time. Correct?
>
> FWIW, I wouldn't mind BEGIN { my $::(...) } being disallowed, too
> (consistency).
>
Even if it's legal it's fairly useless because $::(calc_varname()) goes
out of scope at the end of the BEGIN block. You could probably write a
macro to accomplish what you want:
macro declare_var(String $varName) {"\$$varName"}
Then you wouldn't even need the BEGIN block.
my declare_var(calc_varname()) = 42;
The compiler wouldn't know the variable name until runtime, but I think this
just means that this just transforms compile-time errors to runtime errors.
Joe Gottman
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