On Fri, Apr 30, 2021 at 4:23 AM Asher Gordon <asd...@posteo.net> wrote:
> Hello,
>
> I'm writing a new module that exports a similar interface to Type::Tie,
> but performs a type check on the entire variable each time it is
> changed. Obviously, this is much more expensive, but it can be useful
> for types like Types::Standard::Dict in cases where speed is not very
> important.
>
> In case you're not familiar with Type::Tie, here's a brief summary:
> Type::Tie exports a single function, ttie(), which ties variables to
> types. For example, after
>
> use Type::Tie;
> use Types::Standard qw(Num);
>
> ttie my $num, Num;
>
> setting $num to anything but a number will die. And
>
> ttie my @num_list, Num;
>
> only allows numbers in @num_list. So
>
> push @num_list, "foo";
>
> will die.
>
> Type::Tie::Full (the working name for my module) is similar, except that
> the entire variable (as a reference) is passed to the type checker. The
> sole exception to this is tying scalars--in this case, the referenced
> scalar will be passed to the type checker rather than the reference
> itself.
>
> For example, this works correctly:
>
> use Type::Tie::Full;
> use Types::Standard qw(Dict Optional Str Num);
>
> ttie my %dict, Dict[string => Str, number => Optional[Num]],
> string => 'foo';
>
> $dict{string} = 'bar'; # ok
> $dict{number} = 42; # ok
> $dict{nonexistent} = 'foo'; # dies
> $dict{number} = 'foo'; # dies
>
> delete $dict{string}; # dies ('string' is not optional)
> delete $dict{number}; # ok ('number' is optional)
>
> Currently, only one layer of tying is performed, which means things like
> the following don't work how I would like them to:
>
> use Type::Tie::Full;
> use Types::Standard qw(HashRef Num);
>
> ttie my $hashref, HashRef[Num], {};
>
> $hashref = { foo => 'bar' }; # dies ('bar' is not a number)
> $hashref->{foo} = 'bar'; # doesn't die, but probably should
>
> I intend to implement this using deep tying, but it doesn't work for
> now.
>
> My question is, does the name make sense for this module? I figure since
> it performs a full check on the variable every time it is changed (as
> opposed to a check on just the added elements), then it makes sense to
> call it that. Would you agree?
>
Any namespace under Type::Tie you like seems appropriate to me. One
suggestion I have is Type::Tie::Aggregate, since it performs a type check
on the aggregate variables rather than the elements.
-Dan
