Re^2: Eval not trapping fatal error

[Ea]

Of course, you're right.

So, while other constant modules may die and be trapped with eval BLOCK, the constant pragma makes assignment a syntax error and needs to be trapped with eval EXPRESSION. Now I understand the line in the book

the code in the BLOCK has to be valid Perl code to make it past the compilation phase

Thanks

[Corion]

I don't think that you can trap other constant modules with a block eval either. The issue lies with Perl, which doesn't allow a function/subroutine on the left-hand side of an assignment, unless that function is already known as assignable through the :lvalue attribute:

> perl -wle "sub foo {}; eval { foo()='baz' }"
Can't modify non-lvalue subroutine call in scalar assignment at -e lin
+e 1, near "'baz' }"
Execution of -e aborted due to compilation errors.

Marking the subroutine with :lvalue lets Perl know that we intend to let the function appear on the left-hand side of an assignment:

> perl -wle "sub foo:lvalue {}; eval { foo()='baz' }"

All "constant" modules are syntactic sugar for defining functions that take no parameters, because that's how sigil-less constants work in Perl.