statnet.common: persistEval – R documentation

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persistEval

Evaluate an expression, restarting on error

Description

A pair of functions paralleling eval() and evalq() that make multiple attempts at evaluating an expression, retrying on error up to a specified number of attempts, and optionally evaluating another expression before restarting.

Usage

persistEval(
  expr,
  retries = NVL(getOption("eval.retries"), 5),
  beforeRetry,
  envir = parent.frame(),
  enclos = if (is.list(envir) || is.pairlist(envir)) parent.frame() else baseenv(),
  verbose = FALSE
)

persistEvalQ(
  expr,
  retries = NVL(getOption("eval.retries"), 5),
  beforeRetry,
  envir = parent.frame(),
  enclos = if (is.list(envir) || is.pairlist(envir)) parent.frame() else baseenv(),
  verbose = FALSE
)

Arguments

`expr`	an expression to be retried; note the difference between `eval()` and `evalq()`.
`retries`	number of retries to make; defaults to `"eval.retries"` option, or 5.
`beforeRetry`	if given, an expression that will be evaluated before each retry if the initial attempt fails; it is evaluated in the same environment and with the same quoting semantics as `expr`, but its errors are not handled.
`envir, enclos`	see `eval()`.
`verbose`	Whether to output retries.

Value

Results of evaluating expr, including side-effects such as variable assignments, if successful in retries retries.

Note

If expr returns a "try-error" object (returned by try()), it will be treated as an error. This behavior may change in the future.

Examples

x <- 0
persistEvalQ({if((x<-x+1)<3) stop("x < 3") else x},
             beforeRetry = {cat("Will try incrementing...\n")})

x <- 0
e <- quote(if((x<-x+1)<3) stop("x < 3") else x)
persistEval(e,
            beforeRetry = quote(cat("Will try incrementing...\n")))

statnet.common

Common R Scripts and Utilities Used by the Statnet Project Software

v4.4.1

GPL-3 + file LICENSE

Authors

Pavel N. Krivitsky [aut, cre] (<https://orcid.org/0000-0002-9101-3362>), Skye Bender-deMoll [ctb]

Initial release

2020-10-03