Name masking

In programming languages, name resolution refers to the resolution of the tokens within program expressions to the intended program components.

Expressions in computer programs reference variables, data types, functions, classes, objects, libraries, packages and other entities by name. In that context, name resolution refers to the association of those not-necessarily-unique names with the intended program entities. The algorithms that determine what those identifiers refer to in specific contexts are part of the language definition.

The complexity of these algorithms is influenced by the sophistication of the language. For example, name resolution in assembly language usually involves only a single simple table lookup, while name resolution in C++ is extremely complicated as it involves:

In programming languages, name resolution can be performed either at compile time or at runtime. The former is called static name resolution, the latter is called dynamic name resolution.

A somewhat common misconception is that dynamic typing implies dynamic name resolution. However, static typing does imply static name resolution. For example, Erlang is dynamically typed but has static name resolution.

Static name resolution catches, at compile time, use of variables that are not in scope; preventing programmer errors. Languages with dynamic scope resolution sacrifice this safety for more flexibility; they can typically set and get variables in the same scope at runtime.

For example, in Python:

However, relying on dynamic name resolution in code is discouraged by the Python community. The feature also may be removed in a later version of Python.

Examples of languages that use static name resolution include C, C++, E, Erlang, Haskell, Java, Pascal, Scheme, and Smalltalk. Examples of languages that use dynamic name resolution include some Lisp dialects, Perl, PHP, Python, REBOL, and Tcl.

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