CODEWITHSUNDEEP
javastringtemplatestringtemplate-4
pmf
pmf

Reputation: 7749

StringTemplate4 and anonymous templates

I have a problem with the recently released beta version of Stringtemplate 4.

In StringTemplate 3, I used to have templates like

<env_vars:{ var | void* <var>() { return null; }}>

i.e. anonymous templates containing a literal closing brace ("}"), and these worked well enough in ST3 without escaping the first closing brace.

With ST4, I'm getting a NPE (the test case below prints the stack trace). I can get it to work by escaping the closing literal brace, so the template looks like this (notice the quoting backslash in front of the first closing brace):

<env_vars:{ var | void* <var>() { return null; \}}>

But it seems a bit ugly; I've always admired ST's non-intrusive syntax and having to match each "{" to be output with a corresponding "\}" somehow seems very asymmetrical.

Is there something I'm missing or is this an expected change in behavior from ST3?

Test case:

import org.stringtemplate.v4.ST;

public class ST4Test
{
  public static void main(final String[] args)
  {
    final String[] env_vars = new String[]{"one", "two", "three"};

    try
    {

      // This used to work in ST3, but fails in ST4.
      final ST failingST = new ST("<env_vars:{ var | void* <var>() { return null; }}\n>");
      failingST.add("env_vars", env_vars);

      System.out.printf("%s\n", failingST.render());
    }
    catch (Exception ex)
    {
      // The failing example results in a NPE
      ex.printStackTrace();
    }

    // This works, but requires quoting the "}" contained within the anonymous
    // template, which I find a bit disturbing, considering that I use ST for
    // generating C-code, which tends to use the occasional "}", along with the
    // fact that this used to work in ST3.
    final ST workingST = new ST("<env_vars:{ var | void* <var>() { return null; \\}\n}>");
    workingST.add("env_vars", env_vars);
    System.out.printf("%s\n", workingST.render());
  }
}

Upvotes: 4

Views: 1142

Answers (1)

Terence Parr
Terence Parr

Reputation: 5962

I get

test 1:44: invalid character '}'

Are you sure that worked in ST3? The inside } matches but, like quotes, the first } should terminate the template. ST should not interpret text inside templates at all. How about this?

<env_vars:{ var | void* <var>() {{{{{{{{{{{ return null; }>

That should work but wouldn't if i looked at { inside. it could be the head not complete func you're generating, right?

Sounds like v3 had a bug! ;)

Ter

Upvotes: 4

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