Forget HandlesVia for now and consider this:

my @toppings = ( FishTaco::Topping->new );
my $ft = FishTaco->new( _toppings => \@toppings );
push @toppings, "OHAI";

[download]

You can push stuff onto the array without Moo checking that the stuff you're pushing makes any sense. This is because it only checks the array is valid in the constructor and in non-read-only attribute accessors. The exact same happens with Moose.

Moose native traits give you the handles stuff for arrays, and Moose is smart enough to add type checking to push when you do this. MooX::HandlesVia is not quite so smart. (This is partly due to limitations in how Moo works.)

Now try this:

my @toppings = ( FishTaco::Topping->new );
tie @toppings, InstanceOf['FishTaco::Topping'];
my $ft = FishTaco->new( _toppings => \@toppings );
push @toppings, "OHAI";  # this should die

[download]

Yay?

Now play around with trigger.

toby döt ink

In reply to Re: Trouble with, or misunderstanding of, Types::Standard ArrayRef[elements] enforcement in Moo by tobyink
in thread Trouble with, or misunderstanding of, Types::Standard ArrayRef[elements] enforcement in Moo by Your Mother

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