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Full Discussion: Assigning Variables
Top Forums Shell Programming and Scripting Assigning Variables Post 302891115 by Scrutinizer on Tuesday 4th of March 2014 02:42:08 AM
Old 03-04-2014
The first means:
Quote:
${parameter-[word]}
Use Default Values. If parameter is unset, the expansion of word is substituted. Otherwise, the value of parameter is substituted.
The second is a regular variable assignment. The quotes are not necessary:

Both variables are exported.

To give an example:
Code:
$ echo "$var"

$ var=${var-foo}
$ echo "$var"
foo
$ var=
$ var=${var-foo}
$ echo "$var"

$ unset var
$ echo "$var"

$ var=${var-foo}
$ echo "$var"
foo

Last edited by Scrutinizer; 03-04-2014 at 04:00 AM..
This User Gave Thanks to Scrutinizer For This Post:
Arun Mishra
 

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LEARN ABOUT DEBIAN

cgi::formbuilder::template::cgi_ssi

CGI::FormBuilder::Template::CGI_SSI(3pm)		User Contributed Perl Documentation		  CGI::FormBuilder::Template::CGI_SSI(3pm)

NAME

       CGI::FormBuilder::Template::CGI_SSI - FormBuilder interface to CGI::SSI

SYNOPSIS

	   my $form = CGI::FormBuilder->new(
			   fields   => @fields,
			   template => {
			     type => 'CGI_SSI',
			     file => "template.html",
			   },
		      );

DESCRIPTION

       This engine adapts FormBuilder to use "CGI::SSI".

       You can specify any options which "CGI::SSI->new" accepts by using a hashref:

	   my $form = CGI::FormBuilder->new(
			   fields => @fields,
			   template => {
			       type => 'CGI::SSI',
			       file => 'form.shtml',
			       sizefmt => 'abbrev'
			   }
		       );

       In addition to CGI::SSI new arguments, you can also specify "file", "virtual", or "string" argument.

       The following methods are provided (usually only used internally):

   engine
       Returns a reference to the "CGI::SSI" object

   prepare
       Returns a hash of all the fields ready to be rendered.

   render
       Uses the prepared hash and expands the template, returning a string of HTML.

TEMPLATES

       In your template, each of the form fields will correspond directly to a "<!--#echo -->" of the same name prefixed with "field-" in the
       template. So, if you defined a field called "email", then you would setup a variable called "<!--#echo var="field-email" -->" in your
       template.

       In addition, there are a couple special fields:

	   <!--#echo var="js-head" -->	   -  JavaScript to stick in <head>
	   <!--#echo var="form-title" -->  -  The <title> of the HTML form
	   <!--#echo var="form-start" -->  -  Opening <form> tag and internal fields
	   <!--#echo var="form-submit" --> -  The submit button(s)
	   <!--#echo var="form-reset" -->  -  The reset button
	   <!--#echo var="form-end" -->    -  Just the closing </form> tag

       Let's look at an example "form.html" template we could use:

	   <html>
	   <head>
	   <title>User Information</title>
	   <!--#echo var="js-head" --><!-- this holds the JavaScript code -->
	   </head>
	   <!--#echo var="form-start" --><!-- this holds the initial form tag -->
	   <h3>User Information</h3>
	   Please fill out the following information:
	   <!-- each of these <!--#echo -->'s corresponds to a field -->
	   <p>Your full name: <!--#echo var="field-name" -->
	   <p>Your email address: <!--#echo var="field-email" -->
	   <p>Choose a password: <!--#echo var="field-password" -->
	   <p>Please confirm it: <!--#echo var="field-confirm_password-->
	   <p>Your home zipcode: <!--#echo var="field-zipcode -->
	   <p>
	   <!--#echo var="form-submit" --><!-- this holds the form submit button -->
	   </form><!-- can also use "tmpl_var form-end", same thing -->

       As you see, you get a "<!--#echo -->" for each for field you define.

       However, you may want even more control. That is, maybe you want to specify every nitty-gritty detail of your input fields, and just want
       this module to take care of the statefulness of the values. This is no problem, since this module also provides several other "<tmpl_var>"
       tags as well:

	   <!--#echo var="value-[field] -->   - The value of a given field
	   <!--#echo var="label-[field] -->   - The human-readable label
	   <!--#echo var="comment-[field] --> - Any optional comment
	   <!--#echo var="error-[field] -->   - Error text if validation fails
	   <!--#echo var="required-[field] --> - See if the field is required

       This means you could say something like this in your template:

	   <!--#echo var="label-email" -->:
	   <input type="text" name="email" value="<!--#echo var="value-email" -->">
	   <font size="-1"><i><!--#echo var="error-email" --></i></font>

       And FormBuilder would take care of the value stickiness for you, while you have control over the specifics of the "<input>" tag.  A sample
       expansion may create HTML like the following:

	   Email:
	   <input type="text" name="email" value="nate@wiger.org">
	   <font size="-1"><i>You must enter a valid value</i></font>

       Note, though, that this will only get the first value in the case of a multi-value parameter (for example, a multi-select list).  Multiple
       values (loops) in "CGI_SSI" are not yet implemented.

       For more information on templates, see HTML::Template.

SEE ALSO

       CGI::FormBuilder, CGI::FormBuilder::Template, HTML::Template

REVISION

       $Id: HTML.pm 97 2007-02-06 17:10:39Z nwiger $

AUTHOR

       Copyright (c) Nate Wiger <http://nateware.com>. All Rights Reserved.

       This module is free software; you may copy this under the terms of the GNU General Public License, or the Artistic License, copies of which
       should have accompanied your Perl kit.

perl v5.14.2							    2011-09-16				  CGI::FormBuilder::Template::CGI_SSI(3pm)
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