persistEval: Evaluate an expression, restarting on error

In statnet.common: Common R Scripts and Utilities Used by the Statnet Project Software

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 documentation built on Oct. 6, 2024, 5:06 p.m.