scala erb equivalent?

[Maurice Codik-2]

Hey all,

I'm looking for a library similar to Ruby's ERB for scala: something that I can use to embed scala code in ordinary text, and then have that translated into a scala class I can call into. I know I can get close to this by using { expr } in xml tags, but I'd like something I can use outside of xml documents if I need to.

Does something like this exist already? My google-fu is failing me..

Thanks!

Maurice

[bearfeeder]

Short answer: nothing but the built-in XML support.

Why is this failing you?

On 1/9/08, Maurice Codik <mcodik@...> wrote:

Hey all,

I'm looking for a library similar to Ruby's ERB for scala: something that I can use to embed scala code in ordinary text, and then have that translated into a scala class I can call into. I know I can get close to this by using { expr } in xml tags, but I'd like something I can use outside of xml documents if I need to.

Does something like this exist already? My google-fu is failing me..

Thanks!

Maurice

--
lift, the secure, simple, powerful web framework http://liftweb.net
Collaborative Task Management http://much4.us

[Jim Miller-12]

I use the following function that goes through an imput string and calls a function for every occurrence of #{name}, passing 'name' as the argument to the function.

import java.util.regex.{Pattern,Matcher}

def populate (template: String, map : (String) => String ) : String = {
 
  val p = Pattern.compile("#\\{(.+?)\\}");
  val m = p.matcher(template);
  val sb = new StringBuffer();

  while (m.find()) {
    m.appendReplacement(sb, map( m.group(1) ) );
  }

  m.appendTail(sb);

  return sb.toString()
}

Then in practice I do something like:

    populate(
      """XDR.writeInt32(d, #{name}.size() );
          for ( #{type} v : #{name} ) {  XDR.write( d, v ); }
      """,
      tag => tag match {
         case "name" => "foo"
        case "type" => "bar"
      })

I do a LOT of code generation with Scala and this function works out very well.  The nice thing is that I can do anything I want in the case clauses as long as the result is a string for substituting in the template.

On 1/9/08, Maurice Codik <mcodik@...> wrote:

Hey all,

I'm looking for a library similar to Ruby's ERB for scala: something that I can use to embed scala code in ordinary text, and then have that translated into a scala class I can call into. I know I can get close to this by using { expr } in xml tags, but I'd like something I can use outside of xml documents if I need to.

Does something like this exist already? My google-fu is failing me..

Thanks!

Maurice

[Maurice Codik-2]

A few reasons:

- not all documents are xml.

- I've run into a few issues with the built in xml support that make it annoying for use as a templating language for xml. for example, with simple conditionals:

object xml {
  def main(a:Array[String]) {                                                                                                                                                          
    val data = <testing>
                {
                  if (true) {
                    <huh>huh?!</huh>
                  }
               }
               </testing>                                                                                                                  
    Console.println(data)                                                                                                                   
  }
}

only prints: <testing></testing>. I can work around this by adding a dummy else block to that if, but that can get tedious.

there are also some slightly annoying things, like how it turns self closing tags to normal tags: <img src="test.jpg" /> => <img ..></img>

On Jan 9, 2008 9:57 AM, David Pollak < feeder.of.the.bears@...> wrote:

Short answer: nothing but the built-in XML support.

Why is this failing you?

On 1/9/08, Maurice Codik <mcodik@...> wrote:

Hey all,

I'm looking for a library similar to Ruby's ERB for scala: something that I can use to embed scala code in ordinary text, and then have that translated into a scala class I can call into. I know I can get close to this by using { expr } in xml tags, but I'd like something I can use outside of xml documents if I need to.

Does something like this exist already? My google-fu is failing me..

Thanks!

Maurice

--
lift, the secure, simple, powerful web framework http://liftweb.net
Collaborative Task Management http://much4.us

[David Pollak]

Maurice,

Maurice Codik wrote:

A few reasons:

- not all documents are xml.

- I've run into a few issues with the built in xml support that make it annoying for use as a templating language for xml. for example, with simple conditionals:

object xml {
  def main(a:Array[String]) {                                                                                                                                                          
    val data = <testing>
                {
                  if (true) {
                    <huh>huh?!</huh>
                  }
               }
               </testing>                                                                                                                  
    Console.println(data)                                                                                                                   
  }
}

only prints: <testing></testing>. I can work around this by adding a dummy else block to that if, but that can get tedious.

First, this is good practice for remembering that everything in Scala returns a value, but sometimes the value is of type Unit.

Second, you could do something like:

def showIf(test: Boolean)(toShow: => NodeSeq) = if (test) toShow else Text("")

Then you could write showIf(true){<huh>huh?!</huh>}

there are also some slightly annoying things, like how it turns self closing tags to normal tags: <img src="test.jpg" /> => <img ..></img>

There's an XML to String to UTF-8 encoded byte array facility in lift that "does the right thing"(tm) for XML -> XHTMLish stuff that even IE 6 is comfortable with.

On Jan 9, 2008 9:57 AM, David Pollak < feeder.of.the.bears@...> wrote:

Short answer: nothing but the built-in XML support.

Why is this failing you?

On 1/9/08, Maurice Codik <mcodik@...> wrote:

Hey all,

I'm looking for a library similar to Ruby's ERB for scala: something that I can use to embed scala code in ordinary text, and then have that translated into a scala class I can call into. I know I can get close to this by using { expr } in xml tags, but I'd like something I can use outside of xml documents if I need to.

Does something like this exist already? My google-fu is failing me..

Thanks!

Maurice

--
lift, the secure, simple, powerful web framework http://liftweb.net
Collaborative Task Management http://much4.us

[David Bernard-3]

Hi,

Scala can use all the templates lib available in the javaworld like velocity, freemarker, stringtemplate,...
Or simple like the code provide by Jim cf Substitutor from commons-lang.

/davidB

Jim Miller wrote:

> I use the following function that goes through an imput string and calls
> a function for every occurrence of #{name}, passing 'name' as the
> argument to the function.
>
> import java.util.regex.{Pattern,Matcher}
>
> def populate (template: String, map : (String) => String ) : String = {
>  
>   val p = Pattern.compile("#\\{(.+?)\\}");
>   val m = p.matcher(template);
>   val sb = new StringBuffer();
>
>   while (m.find()) {
>     m.appendReplacement(sb, map( m.group(1) ) );
>   }
>
>   m.appendTail(sb);
>
>   return sb.toString()
> }
>
> Then in practice I do something like:
>
>     populate(
>       """XDR.writeInt32(d, #{name}.size() );
>           for ( #{type} v : #{name} ) {  XDR.write( d, v ); }
>       """,
>       tag => tag match {
>          case "name" => "foo"
>         case "type" => "bar"
>       })
>
> I do a LOT of code generation with Scala and this function works out
> very well.  The nice thing is that I can do anything I want in the case
> clauses as long as the result is a string for substituting in the template.
>
> On 1/9/08, *Maurice Codik* <mcodik@... <mailto:mcodik@...>>
> wrote:
>
>     Hey all,
>
>     I'm looking for a library similar to Ruby's ERB for scala: something
>     that I can use to embed scala code in ordinary text, and then have
>     that translated into a scala class I can call into. I know I can get
>     close to this by using { expr } in xml tags, but I'd like something
>     I can use outside of xml documents if I need to.
>
>     Does something like this exist already? My google-fu is failing me..
>
>     Thanks!
>
>     Maurice
>
>
>

[Maurice Codik-2]

Second, you could do something like:

def showIf(test: Boolean)(toShow: => NodeSeq) = if (test) toShow else Text("")

very neat! I still dont know the language enough to realize things like that are doable. thanks.

I think Jim's solution is pretty cool too, and generally useful for simple string interpolation.. maybe something like that would be good to add to scalax/scalaz ?

davidB brings up a good point-- I hadn't really looked at many of the templating solutions from Java yet.. I'll take a look at those before trying to roll my own erb-clone (which I might do anyway for fun).

thanks for all the replies!