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Get Message

get_message.Rd

Evaluate an instruction written between "" and return the first of the error message, or the last of the warning or standard (non error non warning) messages if ever exist.

Using argument print_no = FALSE, return NULL if nothing reported, which is convenient in some cases.

Usage

get_message(
  data,
  kind = "error",
  header = TRUE,
  print_no = FALSE,
  text = NULL,
  env = NULL,
  safer_check = TRUE,
  lib_path = NULL,
  error_text = ""
)

Arguments

data

Single character string of an instruction to evaluate

kind

Single character string. Either "error" to get a potential error message, or "warning" to get a potential warning message, or "message" to get a potential standard (non error and non warning) message.

header

Single logical value. Add a header in the returned message?

print_no

Single logical value. Print a message saying that nothing (NULL output) has to be reported?

text

Single character string added to the header of the output message, even if nothing reported (print_no is TRUE). Ignored if the header argument is FALSE. Write NULL if not required.

env

An object corresponding to an existing environment. Then the data argument value is evaluated only in the indicated environment. Write NULL if not required (R scope is used). Example env = .GlobalEnv. Example env = asNamespace("stats").

safer_check

Single logical value. Perform some "safer" checks? If TRUE, checkings are performed before main code running (see the safer-r project): 1) correct lib_path argument value 2) required functions and related packages effectively present in local R libraries and 3) R classical operators (like "<-") not overwritten by another package because of the R scope. Must be set to FALSE if this function is used inside another "safer" function to avoid pointless multiple checkings.

lib_path

Vector of characters specifying the absolute pathways of the directories containing the required packages for the function, if not in the default directories. Useful when R packages are not installed in the default directories because of lack of admin rights. More precisely, lib_path is passed through the new argument of .libPaths() so that the new library paths are unique(c(new, .Library.site, .Library)). Warning: .libPaths() is restored to the initial paths, after function execution. Ignored if NULL (default) or if the safer_check argument is FALSE: only the pathways specified by the current .libPaths() are used for package calling.

error_text

Single character string used to add information in error messages returned by the function, notably if the function is inside other functions, which is practical for debugging. Example: error_text = " INSIDE <PACKAGE_1>::<FUNCTION_1> INSIDE <PACKAGE_2>::<FUNCTION_2>.". If NULL, converted into "".

Value

The function returns the error, warning, or standard message, as a single character string, depending on what has been selected using the kind argument and if such message exists.

NULL if no selected message returned and the print_no argument is FALSE.

The following message if no selected message returned and the print_no argument is TRUE: "NO (ERROR|WARNING|STANDARD) MESSAGE REPORTED".

The following message if 1) the kind argument is "warning" or "message" while an error message is returned and 2) the print_no argument is TRUE: "NO POTENTIAL (WARNING|STANDARD) MESSAGE BECAUSE OF ERROR MESSAGE REPORTED".

Details

Warnings:

  • Only the first error or last warning/standard message is returned.

  • Always use the env argument when get_message() is used inside functions.

  • The function does not prevent printing, for instance if print() or show() is used inside the instruction tested. To prevent that, use tempo <- utils::capture.output(error <- get_message(data = "arg_check(data = 'a', class = mean, neg_values = FALSE, print = TRUE)")). The return of get_message() is assigned into error and the printed messages are captured by utils::capture.output() and assigned into tempo. See the examples.

See also

try.

Author

Gael Millot

Yushi Han

Haiding Wang

Examples

# Warning: these examples may not work well when using the "Run examples" link 
# because of a particular environment. Please, copy-paste in a local environment.
# See also https://safer-r.github.io/saferDev/articles/get_message.html

# Report error message by default. Here no error to report:
saferDev::get_message(data = "wilcox.test(c(1,1,3), c(1, 2, 4), paired = TRUE)")
#> NULL

# Warning message to report:
saferDev::get_message(data = "wilcox.test(c(1,1,3), c(1, 2, 4), paired = TRUE)", kind = "warning")
#> [1] "WARNING MESSAGE REPORTED:\nIn wilcox.test.default(c(1, 1, 3), c(1, 2, 4), paired = TRUE): cannot compute exact p-value with zeroes\n"

# No standard message to report:
saferDev::get_message(data = "wilcox.test(c(1,1,3), c(1, 2, 4), paired = TRUE)", kind = "message", 
print_no = TRUE, text = "IN A")
#> [1] "NO STANDARD MESSAGE REPORTED IN A"

# Standard message cannot be caught because wilcox.test() returns an error message:
saferDev::get_message(data = "wilcox.test()", kind = "message", print_no = TRUE, text = "IN A")
#> [1] "NO POTENTIAL STANDARD MESSAGE BECAUSE OF ERROR MESSAGE REPORTED IN A"

# Text added in warning message to report:
saferDev::get_message(data = "wilcox.test()", kind = "error", print_no = TRUE, text = "IN A")
#> [1] "ERROR MESSAGE REPORTED IN A:\nIn wilcox.test.default() : argument \"x\" is missing, with no default\n"

# No error message to report with text added:
saferDev::get_message(data = "sum(1)", kind = "error", print_no = TRUE, text = "IN A")
#> [1] "NO ERROR MESSAGE REPORTED IN A"

# No error message to report with text added:
saferDev::get_message(data = "message('ahah')", kind = "error", print_no = TRUE, text = "IN A")
#> [1] "NO ERROR MESSAGE REPORTED IN A"

# Standard message reported with text added:
saferDev::get_message(data = "message('ahah')", kind = "message", print_no = TRUE, text = "IN A")
#> ahah
#> [1] "NO STANDARD MESSAGE REPORTED IN A"

# Messages from ggplot2 functions caugth:
saferDev::get_message(data = "ggplot2::ggplot(data = data.frame(X = 1:10, stringsAsFactors = TRUE), 
mapping = ggplot2::aes(x = X)) + ggplot2::geom_histogram()", kind = "message", 
print_no = TRUE, text = "IN INSTRUCTION 1")
#> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.
#> [1] "NO STANDARD MESSAGE REPORTED IN INSTRUCTION 1"