R | data.frame to "plain text"

I need to "convert" a data.frame object into plain text (like the print output to the console.

So far I created the following function (using the stringr package) but I wonder if an already implemented function or a more efficient approach exists:

toString.data.frame = function(object, ...) {
    maxLen = max(
                stringr::str_length(apply(object, c(1,2), as.character)), 
                stringr::str_length(names(object))
                );

    # data-frame to character matrix
    txt = apply(object, c(1,2), stringr::str_pad, width=maxLen+5, side="left");
    # concatenate the columns
    txt = apply(txt, 1, paste, collapse="");
    # concatenate the rows
    txt = paste(txt, collapse="\n");
    # add column names
    txt = paste( # concatenate header and body 
            paste( # concatenate all the headers 
                stringr::str_pad( # add 5 spaces on the left of each header
                    stringr::str_pad(names(object), width=maxLen, side="right") # fill each header
                    , width=maxLen+5, side="left")
                , collapse="")
            , txt
            , sep="\n");

    return(txt);
}

I add some runnable code as well as an output example (each output row is delimited by "|")

df = data.frame(hello=rnorm(1:15), world=rnorm(1:15));
cat(toString(object), "\n");


|         a                       b              |    
|       0.217785930312173        1.35892062758937|
|     -0.0529272009376736        -1.3537444650507|
|     -0.0914533595349014      -0.283164123247757|
|       0.209099248751634      -0.994596208802379|
|        1.41207193727609       0.754568758899429|
|      0.0271570788346636       0.722728545001598|
|        1.09160395973882      -0.466194711071017|
|      -0.676012596015548       0.247534965195453|
|        0.36022565974381      -0.318822054653857|
|       0.330251755314496      -0.379818935427323|
|        1.29858423625996       0.393100959746072|
|        1.79061048596737       0.124484229714237|
|      -0.636849202004066       -1.48651181772674|
|        1.08795175312078       0.231693241998673|
|      -0.810214549466222      -0.753200696904484|