Ilya Zakharevich


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


  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/;


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


where $term is a return value of Term::ReadLine->Init.


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


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.


gets an input line, possibly with actual readline support. Trailing newline is removed. Returns undef on EOF.


adds the line to the history of input, from where it can be used if the actual readline is present.


return the filehandles for input and output or undef if readline input and output cannot be used for Perl.


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.


returns an array with two strings that give most appropriate names for files for input and output using conventions "<$in", ">out".


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.

Actually Term::ReadLine can use some other package, that will support reacher set of commands.