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Term::ReadLine(3)      Perl Programmers	Reference Guide	     Term::ReadLine(3)

NAME
       Term::ReadLine -	Perl interface to various "readline" packages.	If no
       real package is found, substitutes stubs	instead	of basic functions.

SYNOPSIS
	 use Term::ReadLine;
	 my $term = Term::ReadLine->new('Simple	Perl calc');
	 my $prompt = "Enter your arithmetic expression: ";
	 my $OUT = $term->OUT || \*STDOUT;
	 while ( defined ($_ = $term->readline($prompt)) ) {
	   my $res = eval($_);
	   warn	$@ if $@;
	   print $OUT $res, "\n" unless	$@;
	   $term->addhistory($_) if /\S/;
	 }

DESCRIPTION
       This package is just a front end	to some	other packages.	It's a stub to
       set up a	common interface to the	various	ReadLine implementations found
       on CPAN (under the "Term::ReadLine::*" namespace).

Minimal	set of supported functions
       All the supported functions should be called as methods,	i.e., either
       as

	 $term = Term::ReadLine->new('name');

       or as

	 $term->addhistory('row');

       where $term is a	return value of	Term::ReadLine->new().

       "ReadLine"  returns the actual package that executes the	commands.
		   Among possible values are "Term::ReadLine::Gnu",
		   "Term::ReadLine::Perl", "Term::ReadLine::Stub".

       "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 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".

		   The strings returned	may not	be useful for 3-argument
		   open().

       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
       a richer	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).

       "event_loop"
		   Registers call-backs	to wait	for user input (i.e., during
		   "readline" method).	This supersedes	tkRunning.

		   The first call-back registered is the call back for
		   waiting.  It	is expected that the callback will call	the
		   current event loop until there is something waiting to get
		   on the input	filehandle.  The parameter passed in is	the
		   return value	of the second call back.

		   The second call-back	registered is the call back for
		   registration.  The input filehandle (often STDIN, but not
		   necessarily)	will be	passed in.

		   For example,	with AnyEvent:

		     $term->event_loop(sub {
		       my $data	= shift;
		       $data->[1] = AE::cv();
		       $data->[1]->recv();
		     },	sub {
		       my $fh =	shift;
		       my $data	= [];
		       $data->[0] = AE::io($fh,	0, sub { $data->[1]->send() });
		       $data;
		     });

		   The second call-back	is optional if the call	back is
		   registered prior to the call	to $term->readline.

		   Deregistration is done in this case by calling event_loop
		   with	"undef"	as its parameter:

		       $term->event_loop(undef);

		   This	will cause the data array ref to be removed, allowing
		   normal garbage collection to	clean it up.  With AnyEvent,
		   that	will cause $data->[0] to be cleaned up,	and AnyEvent
		   will	automatically cancel the watcher at that time.	If
		   another loop	requires more than that	to clean up a file
		   watcher, that will be up to the caller to handle.

       "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 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 sans ornaments
	 export	"PERL_RL= o=0"	   # Use best available	ReadLine sans ornaments

       (Note that processing of	"PERL_RL" for ornaments	is in the discretion
       of the particular used "Term::ReadLine::*" package).

perl v5.32.0			  2020-06-14		     Term::ReadLine(3)

NAME | SYNOPSIS | DESCRIPTION | Minimal set of supported functions | Additional supported functions | EXPORTS | ENVIRONMENT

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