#Smalltalk

I'm not sure if this qualifies:

Smalltalk := Nil.

This deletes the entire run-time environment, hanging the object engine. The only way to fix this is to forcibly terminate the process and restart from backup.

For those that don't know, the way [Visual Works] Smalltalk works is slightly weird. It's like a mini-OS. When you start Smalltalk, you load a "memory image" into RAM, and it continues executing from where it left off. The entire Smalltalk IDE is written in Smalltalk and is dynamically modifiable.

In particular, Smalltalk is a dictionary containing all global variables. Most particularly, every time you declare a new class, a global variable with that name is created, pointing to the Class object for your new class. So setting Smalltalk to Nil (basically null) deletes all classes in the entire system. Even the GUI event handlers go poof.

I have no idea why this variable is even writable. Probably because it's a global variable, and therefore exists as an entry inside itself. (Does your head hurt yet? Did I mention that every object has a class, and classes are objects, so every class has a class? The class of a class is called a metaclass, but a metaclass is also an object, which therefore has a class...)

You could probably achieve a similar effect by clearing the dictionary rather than replacing it with null. Indeed, there's any number of things you could code to delete all the classes in the system, leaving you unable to do anything. But since the actual Smalltalk compiler is also a class... anything that breaks the language also kinda breaks the entire IDE, so...

Smalltalk

I'm not sure if this qualifies:

Smalltalk := Nil.

This deletes the entire run-time environment, hanging the object engine. The only way to fix this is to forcibly terminate the process and restart from backup.

For those that don't know, the way [Visual Works] Smalltalk works is slightly weird. It's like a mini-OS. When you start Smalltalk, you load a "memory image" into RAM, and it continues executing from where it left off. The entire Smalltalk IDE is written in Smalltalk and is dynamically modifiable.

In particular, Smalltalk is a dictionary containing all global variables. Most particularly, every time you declare a new class, a global variable with that name is created, pointing to the Class object for your new class. So setting Smalltalk to Nil (basically null) deletes all classes in the entire system. Even the GUI event handlers go poof.

I have no idea why this variable is even writable. Probably because it's a global variable, and therefore exists as an entry inside itself. (Does your head hurt yet? Did I mention that every object has a class, and classes are objects, so every class has a class? The class of a class is called a metaclass, but a metaclass is also an object, which therefore has a class...)

You could probably achieve a similar effect by clearing the dictionary rather than replacing it with null. Indeed, there's any number of things you could code to delete all the classes in the system, leaving you unable to do anything. But since the actual Smalltalk compiler is also a class... anything that breaks the language also kinda breaks the entire IDE, so...