Term::ReadLine(3)Perl Programmers Reference GuidTerm::ReadLine(3)NAMETerm::ReadLine - Perl interface to various readline
packages. If no real package is found, substitutes stubs
instead of basic functions.
SYNOPSIS
use Term::ReadLine;
$term = new Term::ReadLine 'Simple Perl calc';
$prompt = "Enter your arithmetic expression: ";
$OUT = $term->OUT || STDOUT;
while ( defined ($_ = $term->readline($prompt)) ) {
$res = eval($_), "\n";
warn $@ if $@;
print $OUT $res, "\n" unless $@;
$term->addhistory($_) if /\S/;
}
DESCRIPTION
This package is just a front end to some other packages.
At the moment this description is written, the only such
package is Term-ReadLine, available on CPAN near you. The
real target of this stub package is to set up a common
interface to whatever Readline emerges with time.
Minimal set of supported functions
All the supported functions should be called as methods,
i.e., either as
$term = new Term::ReadLine 'name';
or as
$term->addhistory('row');
where $term is a return value of Term::ReadLine->Init.
ReadLine returns the actual package that executes the
commands. Among possible values are
Term::ReadLine::Gnu, Term::ReadLine::Perl,
Term::ReadLine::Stub Exporter.
new returns the handle for subsequent calls to
following functions. Argument is the name of
the application. Optionally can be followed by
two arguments for IN and OUT filehandles.
These arguments should be globs.
readline gets an input line, possibly with actual
readline support. Trailing newline is removed.
Returns undef on EOF.
addhistory adds the line to the history of input, from
where it can be used if the actual readline is
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present.
IN, $OUT return the filehandles for input and output or
undef if readline input and output cannot be
used for Perl.
MinLine If argument is specified, it is an advice on
minimal size of line to be included into
history. undef means do not include anything
into history. Returns the old value.
findConsole returns an array with two strings that give
most appropriate names for files for input and
output using conventions "<$in", ">out".
Attribs returns a reference to a hash which describes
internal configuration of the package. Names
of keys in this hash conform to standard
conventions with the leading rl_ stripped.
Features Returns a reference to a hash with keys being
features present in current implementation.
Several optional features are used in the
minimal interface: appname should be present
if the first argument to new is recognized,
and minline should be present if MinLine
method is not dummy. autohistory should be
present if lines are put into history
automatically (maybe subject to MinLine), and
addhistory if addhistory method is not dummy.
If Features method reports a feature attribs
as present, the method Attribs is not dummy.
Additional supported functions
Actually Term::ReadLine can use some other package, that
will support reacher set of commands.
All these commands are callable via method interface and
have names which conform to standard conventions with the
leading rl_ stripped.
The stub package included with the perl distribution
allows some additional methods:
tkRunning makes Tk event loop run when waiting for user
input (i.e., during readline method).
ornaments makes the command line stand out by using
termcap data. The argument to ornaments
should be 0, 1, or a string of a form
"aa,bb,cc,dd". Four components of this string
should be names of terminal capacities, first
two will be issued to make the prompt
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standout, last two to make the input line
standout.
newTTY takes two arguments which are input filehandle
and output filehandle. Switches to use these
filehandles.
One can check whether the currently loaded ReadLine
package supports these methods by checking for
corresponding Features.
EXPORTS
None
ENVIRONMENT
The environment variable PERL_RL governs which ReadLine
clone is loaded. If the value is false, a dummy interface
is used. If the value is true, it should be tail of the
name of the package to use, such as Perl or Gnu.
As a special case, if the value of this variable is space-
separated, the tail might be used to disable the ornaments
by setting the tail to be o=0 or ornaments=0. The head
should be as described above, say
If the variable is not set, or if the head of space-
separated list is empty, the best available package is
loaded.
export "PERL_RL=Perl o=0" # Use Perl ReadLine without ornaments
export "PERL_RL= o=0" # Use best available ReadLine without ornaments
(Note that processing of PERL_RL for ornaments is in the
discretion of the particular used Term::ReadLine::*
package).
no real package is found, substitutes stubs instead of
basic functions."
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