Mangler

A mangler is a term used in programming and computing that typically refers to name mangling. This is the process of modifying variable, function, or class names when they are compiled to ensure that they are unique or adhere to a particular naming convention.

Key Uses of a Mangler:

1. C++ and Name Mangling: In languages like C++, name mangling is used to handle function overloading, which allows functions with the same name but different parameter types. Since the linker (the part of the compiler that links compiled code) does not support function overloading, the compiler "mangles" function names by encoding additional information, like parameter types, into the function name. This allows the linker to differentiate between overloaded functions.

   For instance, a function void foo(int) and void foo(double) might be mangled into something like _Z3fooi and _Z3food, respectively.

2. Linker Compatibility: Name mangling is often necessary for compatibility between languages that have different naming conventions. For instance, if C++ code calls C code or vice versa, the C++ compiler may mangle C++ function names to be compatible with the C naming convention. This is why in C++, you often see extern "C" declarations to prevent name mangling and ensure that the linker recognizes the names as plain C function names.
3. Security and Obfuscation: In some cases, name mangling can be used as a basic form of obfuscation, making it harder for someone to reverse-engineer the compiled code by hiding original function or variable names.

Example of Mangling in Action

Suppose you have the following C++ code:

class MyClass {
   void myFunction(int);
   void myFunction(double);
};

After name mangling, the function names in the compiled code might look something like this:

• MyClass::myFunction(int) → _ZN7MyClass10myFunctionEi
• MyClass::myFunction(double) → _ZN7MyClass10myFunctionEd

Why It Matters

If you're working in languages that support overloading, multiple inheritance, or are compiled to binaries that need interoperability across languages, understanding name mangling can be useful. It allows you to decipher the generated symbol names, debug link errors, or even manually link functions across different parts of a project.

In summary, a mangler (or name mangler) is a mechanism that modifies names in compiled code, especially to make overloaded or namespaced functions unique, help link across languages, or obfuscate names for added security.