ororelse

Ororelse is a term that sometimes appears in discussions of programming language abstract syntax trees, but the standard term is orelse. In Python’s AST (abstract syntax tree), orelse refers to the else-branch of certain control-flow constructs and is a field used by the interpreter and analysis tools to represent the portion of code executed when the primary branch does not run, or when a loop completes without a break.

In CPython’s ast representation, the orelse attribute holds a list of statements. It applies to several node types, most notably If, For, and While. For an If node, the statements in orelse are executed when the test evaluates to false. For For and While nodes, the statements in orelse are executed if the loop finishes normally (i.e., no break interrupts the loop).

An example in textual form: an if x: a() else: b() is represented in the AST by an If node with body containing a(), and orelse containing b(). For loops, a loop’s else-block would appear in the orelse list of the corresponding For or While node.

Tools and workflows that analyze or transform Python code—such as linters, formatters, and code-mutating utilities—rely on the orelse field to accurately preserve or modify the else-clause semantics during processing. It is important to note that orelse is not a separate Python keyword; it is a field name used in the AST to model the else-part of control-flow constructs. In other languages or AST frameworks, similar concepts may be represented with different field names. See also Python AST, ast module, CPython.