[rst]

Plenty of other shells support backticks without the "export -f" magic. They must, as backticks are mandated POSIX behavior; few support "export -f" at all. (And at least one that did, the old Bell Labs post-v7 "Research Unix" shell, used only environment variables with embedded characters which couldn't easily be created by normal means, to avoid the risk of "magic processing" on things like TERM and HTTP_FOO.)

[userbinator]

used only environment variables with embedded characters which couldn't easily be created by normal means

    SOMEVAR="`cat some_binary_file`"

[mzs]

No not like that, something more like this:

()SOMEVAR@%=...

You will get a parse error. There is little more than [a-zA-Z0-9_] you can use in identifiers (except bash adds a few more, grrrr). You can probably pull it of with /usr/bin/env though.