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| built-in variable | #process-input | ||||
| Related Syntax | |||||
Purpose
One of the built-in input sources.
#process-input identifies the default input source that the system supplies to the OmniMark program. This corresponds with what is usually referred to as "standard input" ("stdin") on UNIX systems.
When the "-term" command-line option is given, #process-input is unavailable to the program; attempts to access it will generate an error.
#process-input explicitly identifies a source of input, and can be used as the scanning source in:
do scan
repeat scan
do sgml-parse
scan source of a do sgml-parse
submit
The use of #process-input is subject to the following constraints:
do scan, repeat scan, or submit. If an attempt is made to use it more than once, an error will be generated.
#process-input is usually read incrementally, meaning that the contents of the stream are not all buffered in memory before processing begins. In some situations, however, this is not the case. If you use #process-input as a string expression (for example: length of #process-input), as a passed "value" argument in a function, or as part of a concatenated string (for example: set this-string to str-var || #process-input), the entire contents of #process-input will be read into memory.
scan or submit actions, #process-input either must be the only input source or must be directly output to a stream and read as usual.
Further difficulty arises when #process-input does not have an "end". This can happen when it is piped from a keyboard or other such device, where the input can wait forever for another character. This will "hang" a program that attempts to read in all of #process-input at once.
Because of these difficulties, take care to design your program to read #process-input incrementally.
The appropriate herald type for #process-input is "source".
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Related Syntax #main-input #process-output do sgml-parse submit do scan repeat scan declare #process-input has |
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