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




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".

       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 v5.24.0                      2016-03-01               Term::ReadLine(3pm)

perl 5.24 - Generated Thu Nov 24 13:49:40 CST 2016
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