Tidy evaluation in a custom environment

We recommend using eval_tidy() in your DSLs as much as possible to ensure some consistency across packages (.data and .env pronouns, etc). However, some DSLs might need a different evaluation environment. In this case, you can call eval_tidy_() with the bottom and the top of your custom overscope (see as_overscope() for more information).

eval_tidy_(expr, bottom, top = NULL, env = caller_env())

An expression.


This is the environment (or the bottom of a set of environments) containing definitions for overscoped symbols. The bottom environment typically contains pronouns (like .data) while its direct parents contain the overscoping bindings. The last one of these parents is the top.


The top environment of the overscope. During tidy evaluation, this environment is chained and rechained to lexical enclosures of self-evaluating formulas (or quosures). This is the mechanism that ensures hygienic scoping: the bindings in the overscope have precedence, but the bindings in the dynamic environment where the tidy quotes were created in the first place are in scope as well.


The lexical environment in which to evaluate expr.


Note that eval_tidy_() always installs a .env pronoun in the bottom environment of your dynamic scope. This pronoun provides a shortcut to the original lexical enclosure (typically, the dynamic environment of a captured argument, see enquo()). It also cleans up the overscope after evaluation. See overscope_eval_next() for evaluating several quosures in the same overscope.

  • eval_tidy_
Documentation reproduced from package rlang, version 0.1.1, License: GPL-3

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