evalOrEcho {tis} | R Documentation |
This function parses, evaluates and returns the string given as its
first argument. If it can't, the argument itself is returned. Use of
evalOrEcho
to process arguments inside a function can make for
more flexible code.
evalOrEcho(x, resultMode = NULL, n = 0)
x |
a string or other object to attempt to parse and evaluate. |
resultMode |
a string or NULL. If non-NULL, the evaluation of |
n |
parent generations to go back. The evaluation is attempted in the
enviroment specified by |
Using this function inside another function to process some of its
arguments can be very useful. For example, seriesPlot
has a
number or arguments that specify text labels for headers, subheaders,
footnotes, axis labels, and so on. One of those arguments is
sub
, which specifies the subheader. By doing this:
sub <- evalOrEcho(sub, resultMode = "character")
seriesPlot
can handle the sub
argument given in any of
these forms:
sub = "This is a simple subtitle"
.
sub = c("this is a two", "line subtitle")
.
sub = 'c("this is another", "two line subtitle")'
.
If x
is successfully parsed and evaluated, and its mode matches
resultMode
(if supplied), the resulting object is returned.
Otherwise, x
itself is returned.