$Post¶

Status: Stable

documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

Description¶

$Post
    is a global variable whose value, if set, is applied to every
    output expression after evaluation.

Examples¶

No verified examples yet for this function.

Implementation notes¶

A REPL session hook, not a builtin. Registered (docstring only, no default OwnValue) in repl_hooks_init (src/repl_hooks.c). In each REPL cycle repl.c calls repl_apply_post(result) on the evaluator's output; when an OwnValue is set the helper builds $Post[expr] and runs it through evaluate() via hook_call_eval. This happens after evaluation and before Out[n] is stored, so $Post can transform the visible result. Unset = identity.

Attributes: none registered.

Implementation status¶

Stable — documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

References¶

Source: src/repl_hooks.c
Specification: docs/spec/builtins/control-flow.md

Notes & additional examples¶

Worked examples¶

In[1]:= $Post = Framed
Out[1]= Framed[Framed]

In[2]:= 2 + 2
Out[2]= Framed[4]

Notes¶

$Post, if set, is applied to every output expression after evaluation. Here $Post = Framed wraps each result in Framed[...] (note the assignment's own echo is also wrapped). Unset by default, in which case results are shown unmodified.