Re: Could we have elegant version requirement from 5.3 on?
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- Subject: Re: Could we have elegant version requirement from 5.3 on?
- From: Ulrich Schmidt <u.sch.zw@...>
- Date: 2014年3月26日 08:10:28 +0100
Hi Dirk.
Your test for required modules is possible already.
--8<------------------------------------
if not package.loaded.bit32 then
print("QQ...")
os.exit()
end
--8<------------------------------------
And yes, you are right, the _VERSION-string could be easier to test.
It should be a array instead a string containing:
--8<------------------------------------
_VERSION = {
copyright = "Lua-5.3 #some more text if wanted."
-- "5.3" can easily extracted. its between first "-"
-- and first space.
api_version = 53 -- int: version * 10
jit_version = 50 -- int: if luajit is running, else: nil
-- more fields if necessary ...
}
--8<------------------------------------
Ulrich Schmidt.
Am 26.03.2014 07:46, schrieb Dirk Laurie:
There seems to be no way of making Lua code say politely:
"This program requires Lua 5.3" when running under Lua 5.2.
Instead, one gets a nasty message like
./myprog.lua:28: unexpected symbol near '&'
as soon as it hits a bitwise operator.
But maybe it is not late for next time round. We are already
ignoring one leading `#` line. We could equally well ignore
all leading `#` lines and tag some of them as expressions to be
asserted _before_ proceeding to lexical analysis of the file.
This would allow elegant version control and more.
E.g.
#! /usr/bin/env lua
#@ _VERSION >= 6.0
#@ bit32
When Lua 5.3 runs this program, or Lua 6.0 runs it without
having preloaded a bit32 library, the rest of the file would not
even be looked at.