Template toolkit array empty

You can also specify expressions using the logical and , or , not ,? The div operator returns the integer result of division. This can be useful when a variable is bound to a sub-routine or object method which you want to call but aren't interested in the value returned.

The SET directive allows you to assign new values to existing variables or create new temporary variables. Variables may be assigned the values of other variables, unquoted numbers 2. In the latter case, any variable references within the text will be interpolated when the string is evaluated.

Multiple variables may be assigned in the same directive and are evaluated in the order specified. Thus, the above could have been written:. In Perl 5, the. Note that the operator must be specified with surrounding whitespace which, as Larry says, is construed as a feature:. You can, of course, achieve a similar effect with double quoted string interpolation. This can be particularly useful in common template components to ensure that some sensible default are provided for otherwise undefined variables.

No attempt to parse or process the file is made. The contents, possibly including any embedded template directives, are inserted intact. Absolute i. Both these options are disabled by default.

For convenience, the filename does not need to be quoted as long as it contains only alphanumeric characters, underscores, dots or forward slashes. Names containing any other characters should be quoted. All files should be unquoted names or quoted strings. Any variables should be interpolated into double-quoted strings. If a BLOCK of the specified name is defined in the same file, or in a file from which the current template has been called i. Any template directives embedded within the file will be processed accordingly.

All variables currently defined will be visible and accessible from within the included template. Local variable definitions may be specified after the template name, temporarily masking any existing variables. Insignificant whitespace is ignored within directives so you can add variable definitions on the same line, the next line or split across several line with comments interspersed, if you prefer.

Any changes made within the included template will not affect variables in the including template. Technical Note: the localisation of the stash that is, the process by which variables are copied before an INCLUDE to prevent being overwritten is only skin deep.

The top-level variable namespace hash is copied, but no attempt is made to perform a deep-copy of other structures hashes, arrays, objects, etc. Therefore, a foo variable referencing a hash will be copied to create a new foo variable but which points to the same hash array. Thus, if you update compound variables e. If you're not worried about preserving variable values, or you trust the templates you're including then you might prefer to use the PROCESS directive which is faster by virtue of not performing any localisation.

However, be aware that because of the localisation issues explained above if you skipped the previous Technical Note above then you might want to go back and read it or skip this section too , the variables might not actually be "local". If the first element of the variable name already references a hash array then the variable update will affect the original variable. This behaviour can be a little unpredictable and may well be improved upon in a future version.

If you know what you're doing with it and you're sure that the variables in question are defined nor not as you expect them to be, then you can rely on this feature to implement some powerful "global" data sharing techniques. Otherwise, you might prefer to steer well clear and always pass simple undotted variables as parameters to INCLUDE and other similar directives. The variable stash is localised once and then the templates specified are processed in order, all within that same variable context.

This makes it slightly faster than specifying several separate INCLUDE directives because you only clone the variable stash once instead of n times , but not quite as "safe" because any variable changes in the first file will be visible in the second, third and so on.

This might be what you want, of course, but then again, it might not. Any changes made to variables within the included template will be visible in the including template. It's not unusual to find yourself adding common headers and footers to pages or sub-sections within a page. Something like this:. The individual template components being included might look like these:.

It encloses a block up to a matching END directive, which is first processed to generate some output. The specification order indicates outermost to innermost wrapper templates. For example, given the following template block definitions:. A BLOCK definition can be used before it is defined, as long as the definition resides in the same file.

The block definition itself does not generate any output. Like a named block, it can contain any other template directives which are processed when the block is defined.

The output generated by the block is then assigned to the variable julius. The enclosing block is processed each time the macro is called. Conditions may be arbitrarily complex and are evaluated with the same precedence as in Perl. Parenthesis may be used to explicitly determine evaluation order. Each CASE directive should contain a single value or a list of values which should match. A Template::Document is a thin object wrapper around a compiled template subroutine.

The object implements a process method which performs a little bit of housekeeping and then calls the template subroutine. So the context fetches a compiled document via its own template method and then gets ready to process it.

It first updates the stash the place where template variables get defined - more on that shortly to set any template variable definitions specified as the second argument by reference to hash array. Then, it calls the document process method, passing a reference to itself, the context object, as an argument.

In doing this, it provides itself as an object against which template code can make callbacks to access runtime resources and Template Toolkit functionality. What we're trying to say here is this: not only does the Template::Context object receive calls from the outside , i. Before we move on to that, here's a simple structure diagram showing the outer layers of the Template Toolkit heading inwards, with pseudo code annotations showing a typical invocation sequence.

To understand more about what's going on in these lower levels, we need to look at what a compiled template looks like. In fact, a compiled template is just a regular Perl sub-routine. Here's a very simple one.

You're unlikely to see a compiled template this simple unless you wrote it yourself but it is entirely valid. All a template subroutine is obliged to do is return some output which may be an empty of course. If it can't for some reason, then it should raise an error via die. If it wants to get fancy, it can raise an error as a Template::Exception object.

An exception object is really just a convenient wrapper for the ' type ' and ' info ' fields. Templates generally need to do a lot more than just generate static output or raise errors. They may want to inspect variable values, process another template, load a plugin, run a filter, and so on.

Whenever a template subroutine is called, it gets passed a reference to a Template::Context object. It is through this context object that template code can access the features of the Template Toolkit. We described earlier how the Template::Service object calls on Template::Context to handle a process request from the outside. Returns a list of both the keys and the values expanded into a single list.

This method currently returns the same thing as the items method. However, please note that this method will change in the next major version of the Template Toolkit v3 to return the same thing as the pairs method. This will be done in an effort to make these virtual method more consistent with each other and how Perl works.

In anticipation of this, we recommend that you stop using hash. They are returned in sorted order according to the keys. Returns the contents of the hash in list form.

An argument can be passed to indicate the desired items required in the list: keys to return a list of the keys same as hash. When called without an argument it currently returns the same thing as the pairs method. However, please note that this method will change in the next major version of the Template Toolkit v3 to return a reference to a list containing the single hash reference as per the scalar list method.

Return a list of the keys, sorted alphabetically sort or numerically nsort according to the corresponding values in the hash. The import method can be called on a hash array to import the contents of another hash array.

You can also call the import method by itself to import a hash array into the current namespace hash. Returns a true or false value if an item in the hash denoted by the key passed as an argument is defined or exists, respectively. When called without any argument, hash. The item is not removed from the list.

If either is given a numeric argument n , they return the first or last n elements:. Returns the size of a list number of elements and the maximum index number size - 1 , respectively.

Returns a true or false value if the item in the list denoted by the argument is defined. When called without any argument, list. Joins the items in the list into a single string, using Perl's join function. Returns a list of the items in the list that match a regular expression pattern. Returns the items in alpha sort or numerical nsort order.

An argument can be provided to specify a search key. Where an item in the list is a hash reference, the search key will be used to retrieve a value from the hash which will then be used as the comparison value. Where an item is an object which implements a method of that name, the method will be called to return a comparison value. In the example, the books list can contains hash references with an author key or objects with an author method.

In this case the books will be sorted primarily by author. If two or more books have authors with the same name then they will be sorted by title. It is mature, reliable and well documented, and is used to generate content for countless web sites ranging from the very small to the very large. It is written in the Perl programming language but you don't need to know any Perl to use it. In fact, it was specifically created to allow web designers and developers to concentrate on generating web pages without getting bogged down in programming matters.

We call this a "Clear Separation of Concerns" and it makes the whole processes of building, updating and maintaining a web site or web application significantly easier.