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).