phpman > perldoc > Term::ReadLine

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).