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| Related Syntax | Related Concepts | ||||||||
| action | open | ||||||||
Syntax
open stream-name indexer? open-modifiers? as attachment
Setting a stream to open allows it to be written to and causes previous contents to be lost, just as though the stream had been discarded.
A stream can be opened if it is:
The permitted attachments are:
buffer, which opens the stream as a buffer.
referent string-expression, which opens the stream as a referent whose name is given by the string expression.
file string-expression, which opens the stream as a file whose name is given by the string expression. This is the recommended way to open files.
external-output-function call, which opens the stream as a "connection" to an external output function. When data is written to the stream, it is processed by the external output function. This extends the ways in which OmniMark interacts with the external environment, simply by adding external function libraries.
Open modifiers are modifiers that affect how the stream is opened. If more than one open modifier is specified, they must be enclosed in parentheses and separated by "&". Each modifier can be specified only once. The modifiers are:
binary
binary-mode
break-width
buffered
domain-free
referents-allowed
referents-displayed
referents-not-allowed
text-mode
unbuffered
(Note that for backward compatibility, OmniMark allows the file keyword to be omitted from the file attachment. This practice is deprecated in versions of OmniMark later than V3.)
local stream x ... open x as binary-mode file "y" open x as file binary-mode file "y" open x with binary-mode as file "y" open x with buffered as file "y" open x with unbuffered text-mode as file "y"
This code fragment includes five different open...as file statements. The first two are equivalent, though the second is the more efficient form of the statement. The third action is different.
In the first action, note that binary-mode file "y" is a string expression, whose value is the content of the binary file named "y". This is the deprecated form of "open...as file" (with the keyword file omitted), so that x is opened as a file whose name is contained in the binary file "y". On systems where text-mode is the default, x will be opened in text mode; on other systems, it will be opened in binary mode.
The second action is a slightly clearer way of doing the same thing as the first action. You are strongly encouraged to use this second form instead of the first.
The third action opens x in binary mode with the name "y".
The fourth action opens x as a buffered file with the name "y".
The fifth action opens x as an unbuffered file in text mode with the name "y".
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Related Syntax file reopen |
Related Concepts Buffering I/O Output Security considerations Variables |
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