275 lines
7.6 KiB
Markdown
275 lines
7.6 KiB
Markdown
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# Tips & Tricks
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## Blank Variable Handling
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There may be times when you want to print a default value for an empty
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variable instead of printing nothing, such as printing ` ` so that
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html table backgrounds work properly. Many would use an
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[`{if}`](../designers/language-builtin-functions/language-function-if.md) statement to handle this, but there is a
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shorthand way with Smarty, using the
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[`default`](../designers/language-modifiers/language-modifier-default.md) variable modifier.
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> **Note**
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>
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> "Undefined variable" errors will show an E\_NOTICE if not disabled in
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> PHP's [`error_reporting()`](https://www.php.net/error_reporting) level or
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> Smarty's [`$error_reporting`](../programmers/api-variables/variable-error-reporting.md) property and
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> a variable had not been assigned to Smarty.
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```smarty
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{* the long way *}
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{if $title eq ''}
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{else}
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{$title}
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{/if}
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{* the short way *}
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{$title|default:' '}
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```
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See also [`default`](../designers/language-modifiers/language-modifier-default.md) modifier and [default
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variable handling](#default-variable-handling).
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## Default Variable Handling
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If a variable is used frequently throughout your templates, applying the
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[`default`](../designers/language-modifiers/language-modifier-default.md) modifier every time it is
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mentioned can get a bit ugly. You can remedy this by assigning the
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variable its default value with the
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[`{assign}`](../designers/language-builtin-functions/language-function-assign.md) function.
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{* do this somewhere at the top of your template *}
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{assign var='title' value=$title|default:'no title'}
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{* if $title was empty, it now contains the value "no title" when you use it *}
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{$title}
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See also [`default`](../designers/language-modifiers/language-modifier-default.md) modifier and [blank
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variable handling](#blank-variable-handling).
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## Passing variable title to header template
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When the majority of your templates use the same headers and footers, it
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is common to split those out into their own templates and
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[`{include}`](../designers/language-builtin-functions/language-function-include.md) them. But what if the header
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needs to have a different title, depending on what page you are coming
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from? You can pass the title to the header as an
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[attribute](../designers/language-basic-syntax/language-syntax-attributes.md) when it is included.
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`mainpage.tpl` - When the main page is drawn, the title of "Main Page"
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is passed to the `header.tpl`, and will subsequently be used as the
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title.
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```smarty
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{include file='header.tpl' title='Main Page'}
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{* template body goes here *}
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{include file='footer.tpl'}
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```
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`archives.tpl` - When the archives page is drawn, the title will be
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"Archives". Notice in the archive example, we are using a variable from
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the `archives_page.conf` file instead of a hard coded variable.
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```smarty
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{config_load file='archive_page.conf'}
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{include file='header.tpl' title=#archivePageTitle#}
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{* template body goes here *}
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{include file='footer.tpl'}
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```
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`header.tpl` - Notice that "Smarty News" is printed if the `$title`
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variable is not set, using the [`default`](../designers/language-modifiers/language-modifier-default.md)
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variable modifier.
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```smarty
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<html>
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<head>
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<title>{$title|default:'Smarty News'}</title>
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</head>
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<body>
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```
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`footer.tpl`
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```smarty
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</body>
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</html>
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```
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## Dates
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As a rule of thumb, always pass dates to Smarty as
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[timestamps](https://www.php.net/time). This allows template designers to
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use the [`date_format`](../designers/language-modifiers/language-modifier-date-format.md) modifier for
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full control over date formatting, and also makes it easy to compare
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dates if necessary.
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```smarty
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{$startDate|date_format}
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```
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This will output:
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```
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Jan 4, 2009
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```
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```smarty
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{$startDate|date_format:"%Y/%m/%d"}
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```
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This will output:
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```
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2009/01/04
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```
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Dates can be compared in the template by timestamps with:
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```smarty
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{if $order_date < $invoice_date}
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...do something..
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{/if}
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```
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When using [`{html_select_date}`](../designers/language-custom-functions/language-function-html-select-date.md)
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in a template, the programmer will most likely want to convert the
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output from the form back into timestamp format. Here is a function to
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help you with that.
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```php
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<?php
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// this assumes your form elements are named
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// startDate_Day, startDate_Month, startDate_Year
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$startDate = makeTimeStamp($startDate_Year, $startDate_Month, $startDate_Day);
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function makeTimeStamp($year='', $month='', $day='')
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{
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if(empty($year)) {
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$year = strftime('%Y');
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}
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if(empty($month)) {
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$month = strftime('%m');
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}
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if(empty($day)) {
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$day = strftime('%d');
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}
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return mktime(0, 0, 0, $month, $day, $year);
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}
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```
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See also [`{html_select_date}`](../designers/language-custom-functions/language-function-html-select-date.md),
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[`{html_select_time}`](../designers/language-custom-functions/language-function-html-select-time.md),
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[`date_format`](../designers/language-modifiers/language-modifier-date-format.md) and
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[`$smarty.now`](../designers/language-variables/language-variables-smarty.md#smarty-now),
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## Componentized Templates
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Traditionally, programming templates into your applications goes as
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follows: First, you accumulate your variables within your PHP
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application, (maybe with database queries.) Then, you instantiate your
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Smarty object, [`assign()`](../programmers/api-functions/api-assign.md) the variables and
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[`display()`](../programmers/api-functions/api-display.md) the template. So lets say for example we
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have a stock ticker on our template. We would collect the stock data in
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our application, then assign these variables in the template and display
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it. Now wouldn't it be nice if you could add this stock ticker to any
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application by merely including the template, and not worry about
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fetching the data up front?
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You can do this by writing a custom plugin for fetching the content and
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assigning it to a template variable.
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`function.load_ticker.php` - drop file in
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[`$plugins directory`](../programmers/api-variables/variable-plugins-dir.md)
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```php
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<?php
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// setup our function for fetching stock data
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function fetch_ticker($symbol)
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{
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// put logic here that fetches $ticker_info
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// from some ticker resource
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return $ticker_info;
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}
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function smarty_function_load_ticker($params, $smarty)
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{
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// call the function
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$ticker_info = fetch_ticker($params['symbol']);
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// assign template variable
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$smarty->assign($params['assign'], $ticker_info);
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}
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```
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`index.tpl`
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```smarty
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{load_ticker symbol='SMARTY' assign='ticker'}
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Stock Name: {$ticker.name} Stock Price: {$ticker.price}
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```
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See also: [`{include}`](../designers/language-builtin-functions/language-function-include.md).
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## Obfuscating E-mail Addresses
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Do you ever wonder how your email address gets on so many spam mailing
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lists? One way spammers collect email addresses is from web pages. To
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help combat this problem, you can make your email address show up in
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scrambled javascript in the HTML source, yet it it will look and work
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correctly in the browser. This is done with the
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[`{mailto}`](../designers/language-custom-functions/language-function-mailto.md) plugin.
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```smarty
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<div id="contact">Send inquiries to
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{mailto address=$EmailAddress encode='javascript' subject='Hello'}
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</div>
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```
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> **Note**
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>
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> This method isn\'t 100% foolproof. A spammer could conceivably program
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> his e-mail collector to decode these values, but not likely\....
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> hopefully..yet \... wheres that quantum computer :-?.
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See also [`escape`](../designers/language-modifiers/language-modifier-escape.md) modifier and
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[`{mailto}`](../designers/language-custom-functions/language-function-mailto.md).
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