Closures in Tcl

a year ago

The article discusses the concept of closures in programming languages, comparing implementations in C++, Python, and Tcl.
In C++, closures can capture variables by value or reference, but capturing by reference can lead to dangling references outside the scope.
Python demonstrates true closures where variables are captured and remain valid outside their original scope.
Tcl lacks built-in closures but offers workarounds using `apply` and namespaces, with TclOO providing a method to simulate closures.
A custom `closure` implementation in Tcl is presented, which copies the environment but allows access to stored variables via a `lexenv` method.
The necessity of manually destroying closures in Tcl is noted as a limitation until TIP 550 is implemented.

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