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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).

       "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 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).

CAVEATS
       It seems that using Term::ReadLine from Emacs minibuffer doesn't work quite right and one will get an
       error message like

           Cannot open /dev/tty for read at ...

       One possible workaround for this is to explicitly open /dev/tty like this

           open (FH, "/dev/tty" )
             or eval 'sub Term::ReadLine::findConsole { ("&STDIN", "&STDERR") }';
           die $@ if $@;
           close (FH);

       or you can try using the 4-argument form of Term::ReadLine->new().



perl v5.12.5                                     2012-11-03                              Term::ReadLine(3pm)