22 lines
833 B
Lua
22 lines
833 B
Lua
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--If the file opens with no problems, io.open will return a
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--handle to the file with methods attached.
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--If the file does not exist, io.open will return nil and
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--an error message.
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--assert will return the handle to the file if present, or
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--it will throw an error with the message returned second
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--by io.open.
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local file = assert(io.open(filename))
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--Without wrapping io.open in an assert, local file would be nil,
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--which would cause an 'attempt to index a nil value' error when
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--calling file:read.
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--file:read takes the number of bytes to read, or a string for
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--special cases, such as "*a" to read the entire file.
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local contents = file:read'*a'
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--If the file handle was local to the expression
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--(ie. "assert(io.open(filename)):read'a'"),
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--the file would remain open until its handle was
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--garbage collected.
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file:close()
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