lua-io-writer

A writer that writes data to a file or file descriptor.

Installation

luarocks install io-writer

Error Handling

the following functions return the error object created by https://github.com/mah0x211/lua-errno module.

w, err = io.writer.new( f [, sec] )

create a new writer instance that writes data to a file or file descriptor.

NOTE

this function uses the dup system call internally to duplicate a file descriptor. thus, data can be write to a file even if the passed file is closed.

Parameters

• f:file*|string|integer: file, filename or file descriptor.
• sec:number: timeout seconds. if nil or <0, wait forever.

Returns

• w:writer: a writer instance.
• err:any: error message.

Example

local dump = require('dump')
local writer = require('io.writer')

local f = assert(io.tmpfile())
local w = writer.new(f)
local n, err, again, remain = w:write('hello', ' writer ', 'world!')

f:seek('set')
print(dump({
    n = n,
    err = err,
    again = again,
    remain = remain,
    content = f:read('*a'),
}))
-- {
--     content = "hello writer world!",
--     n = 19
-- }

fd = writer:getfd()

get the file descriptor of the writer.

Returns

• fd:integer: file descriptor.

writer:set_timeout( [sec] )

set the timeout seconds.

Parameters

• sec:number: timeout seconds. if nil or <0, wait forever.

ok, err = writer:close()

close the writer.

Returns

• ok:boolean: true if succeeded.
• err:any: error message.

n, err, timeout = writer:write( data [, ...] )

write data to the file or file descriptor.

NOTE

if the file descriptor's peer is closed, this method returns nothing.

Parameters

• data:any: data to write. if a non-string value is specified, it is converted to a string by tostring function.
• ...:any: additional data to write. these are concatenated with data.

Returns

• n:integer: number of bytes written.
• err:any: error message.
• timeout:boolean: true if timed out.