R: Class to writing verbose messages to a connection or file

Verbose {R.utils} | R Documentation

## Class to writing verbose messages to a connection or file

### Description

Package: R.utils
Class Verbose

`Object`
`~~|`
`~~+--``Verbose`

Directly known subclasses:
MultiVerbose, NullVerbose

public static class Verbose
extends Object

Class to writing verbose messages to a connection or file.

### Usage

    Verbose(con=stderr(), on=TRUE, threshold=0, asGString=TRUE, timestamp=FALSE,
      removeFile=TRUE, core=TRUE, ...)

### Arguments

`con` | A `connection` or a `character` string filename.
`on` | A `logical` indicating if the writer is on or off.
`threshold` | A `numeric` threshold that the `level` argument of any write method has to be equal to or larger than in order to the message being written. Thus, the lower the threshold is the more and more details will be outputted.
`timestamp` | If `TRUE`, each output is preceded with a timestamp.
`removeFile` | If `TRUE` and `con` is a filename, the file is first deleted, if it exists.
`asGString` | If `TRUE`, all messages are interpreted as `GString` before being output, otherwise not.
`core` | Internal use only.
`...` | Not used.

### Fields and Methods

Methods:

| `as.character` | Returns a character string version of this object.
| `as.double` | Gets a numeric value of this object.
| `as.logical` | Gets a logical value of this object.
| `capture` | Captures output of a function.
| `cat` | Concatenates and prints objects if above threshold.
| `enter` | Writes a message and indents the following output.
| `enterf` | -
| `equals` | Checks if this object is equal to another.
| `evaluate` | Evaluates a function and prints its results if above threshold.
| `exit` | Writes a message and unindents the following output.
| `getThreshold` | Gets current verbose threshold.
| `getTimestampFormat` | Gets the default timestamp format.
| `header` | Writes a header.
| `isOn` | Checks if the output is on.
| `isVisible` | Checks if a certain verbose level will be shown or not.
| `less` | Creates a cloned instance with a higher threshold.
| `more` | Creates a cloned instance with a lower threshold.
| `newline` | Writes one or several empty lines.
| `off` | Turn off the output.
| `on` | Turn on the output.
| `popState` | -
| `print` | Prints objects if above threshold.
| `printf` | Formats and prints object if above threshold.
| `pushState` | Pushes the current indentation state of the Verbose object.
| `ruler` | Writes a ruler.
| `setDefaultLevel` | Sets the current default verbose level.
| `setThreshold` | Sets verbose threshold.
| `setTimestampFormat` | Sets the default timestamp format.
| `str` | Prints the structure of an object if above threshold.
| `summary` | Generates a summary of an object if above threshold.
| `timestamp` | Writes a timestamp.
| `timestampOff` | -
| `timestampOn` | Turns automatic timestamping on and off.
| `warnings` | Outputs any warnings recorded.
| `writeRaw` | Writes objects if above threshold.

Methods inherited from Object:
$, $<-, [[, [[<-, as.character, attach, attachLocally, clearCache, clearLookupCache, clone, detach, equals, extend, finalize, getEnvironment, getFieldModifier, getFieldModifiers, getFields, getInstantiationTime, getStaticInstance, hasField, hashCode, ll, load, names, objectSize, print, save

### Output levels

As a guideline, use the following levels when outputting verbose/debug message using the Verbose class. For a message to be shown, the output level must be greater than (not equal to) current threshold. Thus, the lower the threshold is set, the more messages will be seen.

- <= -100Only for debug messages, i.e. messages containing all necessary information for debugging purposes and to find bugs in the code. Normally these messages are so detailed so they will be a pain for the regular user, but very useful for bug reporting and bug tracking by the developer.

- -99 – -11Detailed verbose messages. These will typically be useful for the user to understand what is going on and do some simple debugging fixing problems typically due to themselves and not due to bugs in the code.

- -10 – -1Verbose messages. For example, these will typically report the name of the file to be read, the current step in a sequence of analysis steps and so on. These message are not very useful for debugging.

- 0Default level in all output methods and default threshold. Thus, by default, messages at level 0 are not shown.

- >= +1Message that are always outputted (if threshold is kept at 0). We recommend not to output message at this level, because methods should be quiet by default (at the default threshold 0).

### A compatibility trick and a speed-up trick

If you want to include calls to Verbose in a package of yours in order to debug code, but not use it otherwise, you might not want to load R.utils all the time, but only for debugging. To achieve this, the value of a reference variable to a Verbose class is always set to `TRUE`, cf. typically an Object reference has value `NA`. This makes it possible to use the reference variable as a first test before calling Verbose methods. Example:

        foo <- function(..., verbose=FALSE) {
          # enter() will never be called if verbose==FALSE, thus no error.
          verbose && enter(verbose, "Loading")
        }

Thus, R.utils is not required for `foo()`, but for `foo(verbose==Verbose(level=-1))` it is.

Moreover, if using the `NullVerbose` class for ignoring all verbose messages, the above trick will indeed speed up the code, because the value of a NullVerbose reference variable is always `FALSE`.

### Extending the Verbose class

If extending this class, make sure to output messages via `*writeRaw()` or one of the other output methods (which in turn all call the former). This guarantees that `*writeRaw()` has full control of the output, e.g. this makes it possible to split output to standard output and to file.

### Author(s)

Henrik Bengtsson

### See Also

`NullVerbose`.

### Examples

    verbose <- Verbose(threshold=-1)

    header(verbose, "A verbose writer example", padding=0)

    enter(verbose, "Analysis A")
    for (kk in 1:10) {
      printf(verbose, "step %d\n", kk)
      if (kk == 2) {
        cat(verbose, "Turning ON automatic timestamps")
        timestampOn(verbose);
      } else if (kk == 4) {
        timestampOff(verbose);
        cat(verbose, "Turned OFF automatic timestamps")
        cat(verbose, "Turning OFF verbose messages for steps ", kk, "-6")
        off(verbose)
      } else if (kk == 6) {
        on(verbose)
        cat(verbose, "Turned ON verbose messages just before step ", kk+1)
      }

      if (kk %in% c(5,8)) {
        enterf(verbose, "Sub analysis #%d", kk)
        for (jj in c("i", "ii", "iii")) {
          cat(verbose, "part ", jj)
        }
        exit(verbose)
      }
    }
    cat(verbose, "All steps completed!")
    exit(verbose)

    ruler(verbose)
    cat(verbose, "Demo of some other methods:")
    str(verbose, c(a=1, b=2, c=3))
    print(verbose, c(a=1, b=2, c=3))
    summary(verbose, c(a=1, b=2, c=3))
    evaluate(verbose, rnorm, n=3, mean=2, sd=3)

    ruler(verbose)
    newline(verbose)

[Package R.utils version 2.7.0 Index]