I am able to use strftime() to convert the current time to a string, but now I need to work the other way around:
{time}Is there a way of doing this within Vim? That is, without the help of external commands, like date.
There's no native function to parse a string into a time. The other direction is possible, though, because the strftime() function you mentioned takes an optional second parameter, {time}.
:echo strftime("%Y %b %d %X", localtime())
2019 Feb 20 12:12:12
The form of the time is seconds since epoch (1/1/1970). localtime() returns current time in that form which is why I used it in the example.
By the way, strftime() isn't portable. It's system dependent both in it's presence or lack there of as well as determining what are valid format strings if it is present.
Since portability is out the window might as well use external commands (e.g. :!date ... if you're on *nix). :)
{time} from anything else other than localtime. But I guess there wasn't the immediate need when these commands were added. And strftime may be portable if the format is well defined, no? %Y shall always return the same thing.
strftime(). I can imagine any number of rationales for this, though. Regarding portability of the specifiers, it's funny that you mention %Y since that is one for which you'll find problem reports. That's due to the C strftime spec not indicating how many digits it should resolve to. Some systems use 2 and others 4. Here's a (dated) example. Googling something like "C strftime portability" will probably reveal other examples.
%Y could problematic. Thanks for sharing!
dateand it is too slow (I'm guessing because it is system call) and was looking for a built-in alternative. Unfortunately, the answer is that there is none.dateis slow for you due to standard library calls or (less likely) actual system calls then I'm guessing a native vim solution probably wouldn't be much help as it likely would use the same facilities. (Similar to how vim'sstrftime()is built onstrftime(3).) What system are you using anyways? Might want to dig into whydateis so slow.