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I want to prompt a user to type some input, and have the prompt display
a default value. Is this possible and if so how? Thanks...

#!/usr/local/bin/perl -- -*-perl-*-
use strict;
use warnings;
my $color = '';
print "What color do you prefer? ";
$color=<STDIN>;
#Q: how do you specify a default value to be inserted at the prompt, eg
"green"?
chop($color);
print "You chose ".$color;

I found a couple functions on the web that sort of do this (though they
don't insert the text at the prompt line):

#!/usr/local/bin/perl -- -*-perl-*-
use strict;
use warnings;
use Text::Wrap;

#DIM VARIABLES
my $color = '';

#GET INPUT
print "What color do you prefer? ";
$color=<STDIN>;
print "you chose ".$color."\n";

$color = &promptUser("What color do you prefer? ", "green");
print "you chose ".$color."\n";

$color = &AskUser("What color do you prefer? ", "blue");
print "you chose ".$color."\n";

################################################## #############################
# VERSION 2
sub AskUser
{
my ($question, $default) = @_;

my $answer;
if (InInteractiveMode())
{
$question .= " [$default]" if (defined $default);
PromptUser2($question);
chomp($answer = <STDIN>);
}

$answer = $default unless (defined $answer and length $answer);

return $answer;
}

sub PromptUser2
{
print(wrap('', '', shift), "\n") if InInteractiveMode();
}

sub InInteractiveMode { return 1 if (-t STDIN and -t STDOUT) }

################################################## #############################
# VERSION 1

#----------------------------( promptUser
)-----------------------------#
#
#
# FUNCTION: promptUser
#
#
#
# PURPOSE: Prompt the user for some type of input, and return the #
# input back to the calling program. #
#
#
# ARGS: $promptString - what you want to prompt the user with #
# $defaultValue - (optional) a default value for the prompt #
#
#
#-------------------------------------------------------------------------#

sub promptUser {


#-------------------------------------------------------------------#
# two possible input arguments - $promptString, and $defaultValue
#
# make the input arguments local variables.
#

#-------------------------------------------------------------------#

my ($promptString,$defaultValue) = @_;


#-------------------------------------------------------------------#
# if there is a default value, use the first print statement; if
#
# no default is provided, print the second string.
#

#-------------------------------------------------------------------#

if ($defaultValue) {
print $promptString, "[", $defaultValue, "]: ";
} else {
print $promptString, ": ";
}

$| = 1; # force a flush after our print
$_ = <STDIN>; # get the input from STDIN (presumably the
keyboard)


#------------------------------------------------------------------#
# remove the newline character from the end of the input the user #
# gave us. #
#------------------------------------------------------------------#

chomp;

#-----------------------------------------------------------------#
# if we had a $default value, and the user gave us input, then #
# return the input; if we had a default, and they gave us no #
# no input, return the $defaultValue. #
# #
# if we did not have a default value, then just return whatever #
# the user gave us. if they just hit the <enter> key, #
# the calling routine will have to deal with that. #
#-----------------------------------------------------------------#

if ("$defaultValue") {
return $_ ? $_ : $defaultValue; # return $_ if it has a value
} else {
return $_;
}
}

################################################## #############################

"Mad Scientist Jr" <> wrote in message
news: oups.com...
>I want to prompt a user to type some input, and have the prompt display
> a default value. Is this possible and if so how? Thanks...
>
> #!/usr/local/bin/perl -- -*-perl-*-
> use strict;
> use warnings;
> my $color = '';
> print "What color do you prefer? ";
> $color=<STDIN>;
> #Q: how do you specify a default value to be inserted at the prompt, eg
> "green"?
> chop($color);

> print "You chose ".$color;
>

Just assign a value if none is entered, or is there something I'm missing
here?

use strict;
use warnings;

print "What color do you prefer? [green] ";

my $color=<STDIN>;

chomp $color;

$color ||= 'green';

print "You chose ".$color;


Matt

Mad Scientist Jr <> wrote:

> $color=<STDIN>;
> chop($color);


Do not use chop() to remove line endings.

Use chomp() to remove line endings.


--
Tad McClellan SGML consulting
Perl programming
Fort Worth, Texas

>Just assign a value if none is entered, or is there something I'm missing here?

Rather than simply print a prompt with the default in brackets like:

<PRE>
Type a color [green]? _
^
cursor is after prompt
</PRE>

I would like the cursor to be IN FRONT of the default value (like it
would in a GUI):

<PRE>
Type a color? green
^
cursor is here, BEFORE default value
</PRE>


Matt Garrish wrote:
> "Mad Scientist Jr" <> wrote in message
> news: oups.com...
> >I want to prompt a user to type some input, and have the prompt display
> > a default value. Is this possible and if so how? Thanks...
> >
> > #!/usr/local/bin/perl -- -*-perl-*-
> > use strict;
> > use warnings;
> > my $color = '';
> > print "What color do you prefer? ";
> > $color=<STDIN>;
> > #Q: how do you specify a default value to be inserted at the prompt, eg
> > "green"?
> > chop($color);
>
> > print "You chose ".$color;
> >
>
> Just assign a value if none is entered, or is there something I'm missing
> here?
>
> use strict;
> use warnings;
>
> print "What color do you prefer? [green] ";
>
> my $color=<STDIN>;
>
> chomp $color;
>
> $color ||= 'green';
>
> print "You chose ".$color;
>
>
> Matt

thanks... I'll give it a try

ps understood about PERL not being a GUI. I'm suprised is even
possible...

Marc Dashevsky wrote:
> Mad Scientist Jr <> writes in article %:
> >
> > >Just assign a value if none is entered, or is there something I'm missing here?
> >
> > Rather than simply print a prompt with the default in brackets like:
> >
> > <PRE>
> > Type a color [green]? _
> > ^
> > cursor is after prompt
> > </PRE>
> >
> > I would like the cursor to be IN FRONT of the default value (like it
> > would in a GUI):
>
> The following does what you want, but it does not erase the default
> value from the screen as soon as you type the first keystroke.
> After all it's not a GUI.
>
> use strict;
> use warnings;
>
> print GetInput('Enter your response', 'This is the default');
>
> sub GetInput {
> my($prompt, $default) = @_;
> print "$prompt: $default";
> print "\010" x length($default);
> my $response = <STDIN>;
> chomp($response);
> return($response || $default);
> }
>
> --
> Go to http://MarcDashevsky.com to send me e-mail.