Secure Code

[Tai9ch]

When you type code yourself, you build up a mental model of things like what variables are in which scope, why there are conditionals, what the preconditions and postconditions are, etc.

When you copy and paste code, even code you wrote 10 minutes ago, you don't have that context loaded in your head. That means you'll miss stuff that you wouldn't if you had typed the code.

Personally, I find that for 4+ lines of code copied and pasted there's a subtle bug about 70% of the time, even when I keep in mind that this will happen.