Suppress any emission of a particular warning message

Question

I have a source file (in knitr) containing plots which use a particular font family. I\'d like to suppress the warning messages

In grid.Call(L_textBo

Answer 1

Use

withCallingHandlers({
    <your code>
}, warning=function(w) {
    if (<your warning>)
        invokeRestart("muffleWarning")
})

For instance,

x = 1
withCallingHandlers({
    warning("oops")
    warning("my oops ", x)
    x
}, warning=function(w) {
    if (startsWith(conditionMessage(w), "my oops"))
        invokeRestart("muffleWarning")
})

produces output

[1] 1
Warning message:
In withCallingHandlers({ : oops
>

The limitation is that the conditionMessage may be translated to another language (especially if from a base function) so that the text will not be reliably identified.

See Selective suppressWarnings() that filters by regular expression.