Ah, sorry, some actual context might be helpful. In Perl, variable declaration was originally even worse than it is in PHP: any variable, anywhere, required no

Ah, sorry, some actual context might be helpful. In Perl, variable declaration was originally even worse than it is in PHP: any variable, anywhere, required no declaration and was assumed to be a global. (This was inherited from... some combination of awk and shell, I guess.) Obvious problems aside, a practical implication was that recursion was pretty awkward, since the callee and the caller were sharing the same namespace for the same code. Perl 5.000 introduced the `my` function, which would declare a variable as lexically scoped. This solved the practical issues, but it left the problem of error-checking: a typo in a variable name would still create an implicit global with no warning. The solution was the opt-in `use strict;` declaration, which disabled the implicit-global behavior and made unrecognized variable names a compile-time error. Code could be fixed and then opt into the stricter semantics on a per-file (or even per-block!) basis, and nowadays most Perl devs will jump on you like a pack of hyenas if your code doesn't start with `use strict;` or some equivalent. Over time other features with too-sharp edges have been culled, still supported by the interpreter (Perl is more or less compatible going back decades) but made illegal in strict mode. JavaScript's weird "use strict" opt-in is a spiritual port of Perl's approach, stuffed into a string literal to fit into the existing syntax. One of its effects is even the same: assigning to an unrecognized name is now illegal, rather than creating an implicit global. I'm not aware of anything so fundamental being changed in such a heavy-handed way in PHP. From the outside looking in, I'm not even sure the PHP community has a strong consensus on what PHP-specific features to avoid. I'd be happy to learn that I'm wrong on either count.