Confusing POSIXlt Warning !!!

[englianhu]

OK so what's happening is that the evaluation environment of j has strptime overwritten locally:

data.table/R/data.table.R

Lines 1151 to 1154 in a8e926a

	SDenv$strptime = function(x, ...) {
	warning("POSIXlt column type detected and converted to POSIXct. We do not recommend use of POSIXlt at all because it uses 40 bytes to store one date. Use as.POSIXct to avoid this warning.")
	as.POSIXct(base::strptime(x, ...))
	}

From there, it doesn't discriminate on whether strptime is operating/producing a column. I don't think there's any easy fix to be more selective on this warning, but the message could be more helpful.

Note that AFAIK strptime can always be replaced by an as.POSIXct call (which wraps to as.POSIXlt-->strptime anyway), in which case j will be ignorant to strptime being called "under the hood" (since the call chain will end up at base::as.POSIXct and so base::strptime is used, not SDenv$strptime)

• 引用：Originally posted by @MichaelChirico in confusing POSIXlt warning #2068 (comment)