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Term::ReadLine

Section: Perl Programmers Reference Guide (3pm)
Updated: perl v5.6.1
Index

NAME

Term::ReadLine - Perl interface to various "readline" packages. Ifno 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 momentthis description is written, the only such package is Term-ReadLine,available on CPAN near you. The real target of this stub package is toset 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""
ReadLine: returns the actual package that executes the commands. Among possiblevalues are "Term::ReadLine::Gnu", "Term::ReadLine::Perl","Term::ReadLine::Stub Exporter".
""new""
new: returns the handle for subsequent calls to followingfunctions. Argument is the name of the application. Optionally can befollowed by two arguments for "IN" and "OUT" filehandles. Thesearguments should be globs.
""readline""
readline: gets an input line, possibly with actual "readline"support. Trailing newline is removed. Returns "undef" on "EOF".
""addhistory""
addhistory: adds the line to the history of input, from where it can be used ifthe actual "readline" is present.
""IN"", $""OUT""
IN, $OUT: return the filehandles for input and output or "undef" if "readline"input and output cannot be used for Perl.
""MinLine""
MinLine: If argument is specified, it is an advice on minimal size of line tobe included into history. "undef" means do not include anything intohistory. Returns the old value.
""findConsole""
findConsole: returns an array with two strings that give most appropriate names forfiles for input and output using conventions ""<$in"", "">out"".
Attribs: returns a reference to a hash which describes internal configurationof the package. Names of keys in this hash conform to standardconventions with the leading "rl_" stripped.
""Features""
Features: Returns a reference to a hash with keys being features present incurrent implementation. Several optional features are used in theminimal interface: "appname" should be present if the first argumentto "new" is recognized, and "minline" should be present if"MinLine" method is not dummy. "autohistory" should be present iflines 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, themethod "Attribs" is not dummy.

Additional supported functions

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

All these commands are callable via method interface and have nameswhich conform to standard conventions with the leading "rl_" stripped.

The stub package included with the perl distribution allows someadditional methods:

""tkRunning""
tkRunning: makes Tk event loop run when waiting for user input (i.e., during"readline" method).
""ornaments""
ornaments: makes the command line stand out by using termcap data. The argumentto "ornaments" should be 0, 1, or a string of a form""aa,bb,cc,dd"". Four components of this string should be names ofterminal capacities, first two will be issued to make the promptstandout, last two to make the input line standout.
""newTTY""
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 supportsthese methods by checking for corresponding "Features".

EXPORTS

None

ENVIRONMENT

The environment variable "PERL_RL" governs which ReadLine clone isloaded. If the value is false, a dummy interface is used. If the valueis 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 tobe "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 isempty, 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).

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