Evalexec

Evalexec is a term used in programming to describe a workflow or interface that separates the evaluation of code from its execution. In this pattern, an input—such as a string, template, or intermediate representation—is first evaluated to produce a value or data structure, and that result is then passed to an execution phase that performs side effects or runs further code. The distinction between evaluating and executing can help structure interpreters, templating engines, or domain-specific languages.

In practice, the evaluation phase resolves expressions, identifiers, and literals to a data form, while the execution phase applies that form to produce outcomes, modify state, or run additional code. This separation is common in dynamic languages, sandboxed evaluators, and build or automation systems. It can support safer evaluation by sandboxing or allow optimizations such as caching, pre-analysis, or staged compilation.

Security and safety are central considerations. Evaluating real-time or untrusted input can enable arbitrary operations, so many environments implement mitigations such as restricted or sandboxed evaluators, limited global scopes, input whitelisting, or the use of restricted domain-specific languages instead of general-purpose evaluators. Performance concerns include repeated parsing and evaluation, which can be alleviated by compiling to an intermediate representation, caching results, or separating the evaluation step from heavy execution.

Related concepts include the familiar eval and exec pairs in languages like Python, JavaScript, or Lisp, where read/evaluate/apply or parse/evaluate/execute cycles are used. The exact meaning and implementations of evalexec vary by ecosystem and are not universally standardized.