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Overview Why Clearsilver? Clearsilver Basics HDF Dataset Template Syntax Expressions Macros Functions CGI Kit Config Vars FAQ API Reference API Concepts C API Python API Introduction Perl API Java API Tools odb.py Comparison with PHP, ASP, JSP Comparison with XML/XSLT |
The dataset and HDF FilesIt is often convenient to load elements of a dataset from disk. Normally data is loaded from a ClearSilver file format called HDF, although it could easily be loaded from XML or another format. HDF stands for Hierarchical Data Format (yes, another HDF). It supports two different syntax for representing the dataset hierarchy which can be intermixed arbitrarily. The first is a simple dotted path scheme:
Page.Name = My Index Page.URL = /myindex.html Page.Menu.0 = Home Page.Menu.1 = Preferences Page.Menu.2 = Help Page.Menu.3 = SupportThe second is a nested elements scheme: Page { Name = My Index URL = /myindex.html Menu { 0 = Home 1 = Preferences 2 = Help 3 = Support } }The hierarchy within an HDF file can be arbitrarily nested and contain any data elements desired. For instance, to extend the format of the Menu above, we could add: Page { Menu { 0 { Name = Home URL = / } 1 { Name = Preferences URL = /prefs } 2 { Name = Help URL = /help.html } 3 { Name = Support URL = /feedback/ } } }Because APIs for HDF support reading and writing files in these formats, HDF can serve as a great configuration or persistence language. However, its primary purpose here is to load static elements into the dataset for use in a ClearSilver template. When a ClearSilver template is rendering, it can reference specific variables in the dataset or iterate over all of the elements at a specific point in the dataset hierarchy. For example, a CS template which was rendering the HDF dataset above might iterate over Page.Menu, rendering each menu item's .Name and .URL elements. There are two more important parts of the HDF file syntax.
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