Wednesday, November 14, 2012

MFlow: now the widgets can express requirements

A widget can need the installation of a client script, a CSS or download them. Also it can need a server process installed. But other widgets in the same page could need the same script. To avoid duplications, and to make easy the development of separated widgets maintaining the modularity, I added requirements.

type Script= String
type OnLoadScript= String
type File= String
data WebRequirement= CSSFile String
                   | CSS Script
                   | JScriptFile File [OnLoadScript]
                   | JScript Script
                   | ServerProc (String, Token -> Workflow IO ())

[OnLoadScript] are scripts called when the script file is loaded.

The syntax is as such:

ask $  requires[WebRequirement
    >> rest of the page

here >> is the monadic operator

For example this widget show set of options in from data from the serves via AJAX,  is defined in MFlow.Forms.Widgets, insert two javascript files, a CSS file and  a script. It can be combined with other widgets that require also these scripts, but the page creation process will just insert a single script tag or css link. The programmer no longer has to care about the requirements of each widget

selectAutocomplete serverproc = do 
    requires [JScript ajaxScript 
             ,JScriptFile jqueryScript [events]
             ,CSSFile jqueryCSS
             ,JScriptFile jqueryUi []]
    ajaxc <- ajaxcommand="ajaxcommand" attr="attr" font="font" text1="text1" value="value">
                         $ \u -> do
                                 r <- font="font" serverproc="serverproc" u="u">
                                 return $ jaddtoautocomp r

      (thediv ! [strAttr "id" "users"] <<< noWidget )
      <++ input ![thetype "text"
                 ,value "select users"
                 ,strAttr "id" "text1"
                 ,strAttr "oninput" ajaxc
                 ,strAttr "autocomplete" "off"]

This example uses the last version of MFlow at
It uses the last version of  Workflow
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