It is sometimes useful to create a promise using a constructed expression, but
delayedAssign will always substitute the expression argument. I am currently
using this pattern to achieve this:
expr <- bquote(…)
eval(call("delayedAssign", x, expr, eval.env = eval_env))
But it would be nice if base R already had a function that takes quoted promise
body. It could be named delayedAssign0 or delayedAssignq (similar to evalq).
The definition of such function would be trivial (just remove substitute from
delayedAssign):
function (x, value, eval.env = parent.frame(1), assign.env = parent.frame(1))
.Internal(delayedAssign(x, substitute(value), eval.env, assign.env))
Maybe R maintainers could consider adding this function? I would be happy to
submit a patch.
Best,
Taras
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