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;
  $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/;
  }

DESCRIPTION

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

  $term->addhistory('row');

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

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

DISCLAIMER

We are painfully aware that these documents may contain incorrect links and misformatted HTML. Such bugs lie in the automatic translation process that automatically created the hundreds and hundreds of separate documents that you find here. Please do not report link or formatting bugs, because we cannot fix per-document problems. The only bug reports that will help us are those that supply working patches to the installhtml or pod2html programs, or to the Pod::HTML module itself, for which I and the entire Perl community will shower you with thanks and praises.

If rather than formatting bugs, you encounter substantive content errors in these documents, such as mistakes in the explanations or code, please use the perlbug utility included with the Perl distribution.

--Tom Christiansen, Perl Documentation Compiler and Editor

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