[Rewrite]Link: Bidirectional Aliasing in Python

This article discusses “Link,” a proposed language feature allowing multiple variable names to reference the same underlying object within a namespace. The author shares experiences from Python-Ideas discussions with core developers.

Notation

The proposed syntax uses a >< b or link a, b to establish connections. Related operations include unlinks a, unlink a, links(), del_and_unlinks a, @link(a,b) decorators, and aka(a) for inspection.

Core Behaviors

Basic linking: When variables link, assignments propagate across all names. Deleting one unlinks all simultaneously.

a >< b
a = 1
print(b)  # 1

Constraints: Only one pre-existing assignment allowed before linking, or a TooManyAssignError raises.

x = 5
x >< y  # OK

a = 1
b = 'foo'
a >< b  # Error

Rationale

Language transitions: Developers moving from JavaScript could bridge naming differences. Example: str.trim >< str.strip

Code clarity: Assigning contextual names reduces cognitive load. The author demonstrates tracking a DataFrame through multiple processing stages with meaningful aliases.

Simplified aliasing: Replaces verbose @property decorators and manual assignment chains in classes.

Compatibility: Library users can rename unfamiliar methods while maintaining functionality.

Multilingual support: Enable class/method names in multiple languages simultaneously.

Implementation Challenges

The author acknowledges significant technical hurdles, citing namespace complexity and performance concerns without presenting solved implementation details.

Similar Concepts

• C++ references (auto & a = b)
• C preprocessor macros
• Python’s assignment chaining