R: Examples for 'R.utils::sourceTo.default'

### ** Examples

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# Example 1
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cat("=== Example 1 ================================================\n")

=== Example 1 ================================================

foo <- function(file, ...) {
  cat("Local objects before calling sourceTo():\n")
  print(ls())

  res <- sourceTo(file, ...)

  cat("Local objects after calling sourceTo():\n")
  print(ls())
}

cat("Global objects before calling foo():\n")

Global objects before calling foo():

lsBefore <- NA
lsBefore <- ls()
foo(file=textConnection(c('a <- 1', 'b <- 2')))

Local objects before calling sourceTo():
[1] "file"
Local objects after calling sourceTo():
[1] "a"    "b"    "file" "res"

cat("Global objects after calling foo():\n")

Global objects after calling foo():

stopifnot(length(setdiff(ls(), lsBefore)) == 0)


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# Example 2 - with VComments preprocessor
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cat("=== Example 2 ================================================\n")

=== Example 2 ================================================

preprocessor <- function(lines, ...) {
  cat("-----------------------------------------\n")
  cat("Source code before preprocessing:\n")
  displayCode(code=lines, pager="console")
  cat("-----------------------------------------\n")
  cat("Source code after preprocessing:\n")
  lines <- VComments$compile(lines)
  displayCode(code=lines, pager="console")
  cat("-----------------------------------------\n")
  lines
}

oldHooks <- getHook("sourceTo/onPreprocess")
setHook("sourceTo/onPreprocess", preprocessor, action="replace")
code <- c(
 'x <- 2',
 '#V1# threshold=-1',
 '#Vc# A v-comment log message',
 'print("Hello world")'
)
fh <- textConnection(code)
sourceTo(fh)

-----------------------------------------
Source code before preprocessing:

Warning: error in running command

-----------------------------------------
Source code after preprocessing:

Warning: error in running command

-----------------------------------------
[1] "Hello world"

setHook("sourceTo/onPreprocess", oldHooks, action="replace")

Examples for 'R.utils::sourceTo.default'

Parses and evaluates code from a file or a connection