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Bug 344875

Summary:

[templates][templates view] TemplateContext.getVariable(String) method always returns null

Product:

[Eclipse Project] JDT

Reporter:

Jim Mayer <jim>

Component:

Text

Assignee:

Dani Megert <daniel_megert>

Status:

RESOLVED WORKSFORME

QA Contact:

Severity:

normal

Priority:

CC:

daniel_megert

Version:

3.7

Target Milestone:

---

Hardware:

All

OS:

All

Whiteboard:

investigate

Attachments:

Description	Flags
Test case	none

Description Jim Mayer

2011-05-05 13:51:47 EDT

Build Identifier: 20110218-0911

It appears to be impossible to write a custom TemplateVariableResolver that references another variable in the TemplateContext.  JavaContext can do this, but relies on non-public methods.

Reproducible: Always

Steps to Reproduce:
1.Build the attached plugin
2.Create a template as described in the plugin documentation.
3.Invoke the plugin and watch the console output.

Comment 1 Jim Mayer

2011-05-05 13:53:23 EDT

Created attachment 194857 [details]
Test case

See the class comment in TestVariableResolver.jar for information on running the test case.

Comment 2 Jim Mayer

2011-05-05 13:55:32 EDT

I should add that I believe this problem applies to all platforms and operating systems.  I have personally observed this behavior on PC based Linux and Windows systems.

Comment 3 Dani Megert

2011-05-06 02:51:40 EDT

The context in JDT is not API and there are no plans to change this. To get a variable you can use org.eclipse.jface.text.templates.TemplateContext.getVariable(String).

Comment 4 Jim Mayer

2011-05-06 08:56:17 EDT

(In reply to comment #3)
> The context in JDT is not API and there are no plans to change this. To get a
> variable you can use
> org.eclipse.jface.text.templates.TemplateContext.getVariable(String).

That is what I tried initially.  The problem is that it doesn't work.  As shown in the attached test case, the org.eclipse.jface.text.templates.TemplateContext.getVariable(String) method always returns null.

The problem is that getVariable(string) is backed by TemplateContext.fVariables, but JavaContext overrides TemplateTranslator.createVariable and builds its own table.  Since JavaContext does not reimplement getVariable, it breaks the TemplateContext contract.

The other potential problem is that it appears that TemplateVariableResolver.resolve(variable,context) is not reevaluated when the dependent template variable is changes.  This means that given a template:

// ${name} -> ${changed:foo(name)}

We'd see the expansions:

(1) // [name] -> [changed]
(2) // [x] -> [changed]
(3) // [xy] -> [changed]
(4) // [xyz] -> [changed]

The "foo" variable resolver does not get called as "name" changes, so, even if it could see "name" (which it can't), it still couldn't expand property.

Perhaps the bug report should be changed to "JavaContext breaks the TemplateContext contract".

-- Jim

Comment 5 Dani Megert

2011-05-06 09:00:19 EDT

>TemplateContext.getVariable(String) method always returns null.
I have problems to believe that because that's what's used in JDT for the template support.

Needs to be investigated to say more.

Comment 6 Dani Megert

2012-01-09 10:59:45 EST

> org.eclipse.jface.text.templates.TemplateContext.getVariable(String) method
> always returns null.

I was not able to reproduce this. If you still have a problem using 3.8 M4 or newer, then please attach the sample plug-in which only uses API.