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query
>>-query(--+-DATETIME--------------------------+--)------------><
+-EXISTS----------------------------+
+-HANDLE----------------------------+
| +-CHAR-+ |
+-+-SEEK-----+--+-READ--+------+--+-+
| +-POSITION-+ | +-LINE-+ | |
| | +-CHAR-+ | |
| +-WRITE--+------+-+ |
| | +-LINE-+ | |
| +-SYS-------------+ |
+-SIZE------------------------------+
+-STREAMTYPE------------------------+
+-TIMESTAMP-------------------------+
Used with these options, the [query]
method returns specific information about a stream. Except for
[query] HANDLE and
[query] POSITION, the
stream
returns the query information even if the stream is not open. A null string
is returned for nonexistent streams.
| DATETIME |
returns the date and time stamps of a persistent stream
in US format.
Stream object - QUERY method
stream_name~query("datetime")
A sample output might
be:
11-12-98 03:29:12
|
| EXISTS |
returns the full path specification of the stream,
if it exists, or a null string. For example:
Stream object - QUERY method
stream_name~query("exists")
A sample output might be:
c:\data\file.txt
|
| HANDLE |
returns the handle associated with the open stream.
Stream object - QUERY method
stream_name~query("handle")
A sample output might be:
3
|
| POSITION |
returns the current read or write position for the
stream, as qualified by the following options:
| READ |
returns the current read position.
|
| WRITE |
returns the current write position.
Note
If the stream is
open for both reading and writing, this returns the read position by default.
Otherwise, this returns the specified position.
|
| CHAR |
returns the position in terms of characters.
This is the default.
|
| LINE |
returns the position in terms of lines. For non-binary streams,
this operation can take a long time to complete. This is because the language
processor starts tracking the current line number if not already doing so, and,
thus, might require a scan of the stream from the top to count the line-end
characters. See
for a detailed discussion of this issue.
Stream object - QUERY method
stream_name~query("position write")
A sample output
might be:
247
|
| SYS |
returns the operating system stream position in terms of
characters.
|
|
| SIZE |
returns the size, in bytes, of a persistent stream.
Stream object - QUERY method
stream_name~query("size")
A sample output might be:
1305
|
| STREAMTYPE |
returns a string indicating whether the stream
object is PERSISTENT,
TRANSIENT, or
UNKNOWN.
|
| TIMESTAMP |
returns the date and time stamps of a persistent stream
in an international format. This is the preferred method of getting the date and
time because it provides the full 4-digit year.
Stream object - QUERY method
stream_name~query("timestamp")
A sample output might be:
1998-11-12 03:29:12
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