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iostream.pl -- Utilities to deal with streams |
This library contains utilities that deal with streams, notably originating from non-built-in sources such as URLs, archives, windows, processes, etc.
The predicate open_any/5 acts as a broker between applications that
can process data from a stream and libraries that can create streams
from diverse sources. Without this predicate, processing data inevitally
follows the pattern below. As call_some_open_variation can be
anything, this blocks us from writing predicates such as load_xml(From,
DOM)
that can operate on arbitrary input sources.
setup_call_cleanup( call_some_open_variation(Spec, In), process(In), close(In)).
Libraries that can open streams can install the hook iostream:open_hook/6 to make their functionality available through open_any/5.
Without loaded plugins, the open_any/5 processes the following
values for Specification. If no rule matches, open_any/5
processes Specification as file(Specification)
.
The typical usage scenario is given in the code below, where <process> processes the input.
setup_call_cleanup( open_any(Spec, read, In, Close, Options), <process>(In), Close).
Currently, the following libraries extend this predicate:
http
and https
schemes.