Hidden Features

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Closing a standard file

As of 5.1.3, it is not permitted to close a standard file (e.g. stdin, stdout, and stderr) due to a bug this can cause[1][5]:

> assert(io.stdout:close())
stdin:1: cannot close standard file

Here's a hack around that, which should be used with caution:

local f = assert(io.open '/dev/null') -- or possibly NUL on Windows
debug.setfenv(io.stdout, debug.getfenv(f))
f:close()
assert(io.stdout:close()) -- ok

Old items

• lua_pushliteral is now documented in 5.1.3: [2][6][7]

• The FrontierPattern was added to the reference manual in Lua 5.2. [3]

• The undocumented newproxy function was removed in Lua 5.2, since it was made redundant by other features added in that version.

• Documentation for package.config was added in Lua 5.2. [4]

See also

• LuaReferenceManualComments - describes certain behaviors not fully documented in the Lua Reference Manual.