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Unevaluated Expressions
Syntax
expression(...)
is.expression(expr)
as.expression(expr)
Value
An object with class ``expression'' containing its
unevaluated arguments. Expression objects are
lists of ``calls'' and so the subsetting operations which apply
to lists also apply to them. For compatibility with S,
the mode function will return "expression"
for expression objects.
is.expression returns TRUE if expr is
an expression object and FALSE otherwise.
as.expression attempts to coerce its argument
into an expression object.
See Also
call, function.
Examples
<![CDATA[length(ex1 <- expression(1+ 0:9))
ex1
eval(ex1)
]]>