Re: [dsdp-mtj-dev] Bug 285699 - [fiximprove]: The type Preferences is de

[Craig Setera <craigjunk@xxxxxxxxxx>]

Jon,

I apologize for not getting to this.  My parents showed up for the weekend, so I didn't have any time to look too far into this.  I did, however, want to see if I could answer any of your questions without too much digging tonight...  my comments are inline with the questions.  Let me know if this helps and how much more detail you need me to dig into when I actually get a bit of time.

Thanks,
Craig



Jon Dearden wrote:

Hi folks,

 

I have been looking into the use of the deprecated Preferences for Bug 285699 - [fiximprove]: The type Preferences is deprecated. The goal of the fix is to replace the use of Preferences with IEclipsePreferences. I could use a few pointers from those more familiar with the code. Below is simplified summary of where preferences are being used followed by a few questions.

 

 

MTJ Core

 

The deprecated Preferences are obtained from MTJCore via getPluginPreferences(). Preferences are used by:

• MTJCore
• AntennaBuildExport
• OTAServer
• EmulatorRunner
• MidletSuiteFactory
• MTJCorePreferenceInitializer
• PreferenceAccessor

 

 

PreferenceAccessor is a helper wrapper around preferences. In PreferenceAccessor, the proper IEclipsePreferences appear to be used only for project preferences while Preferences are used elsewhere. PreferenceAccessor is called by:

• PackageBuilder
• PreprocessorBuilder
• StandardPreverifier
• ObfuscatorTool
• MidletSuiteProject

 

 

MTJ UI

 

Preferences are used by:

• AntennaBuildExportAction
• NewMidletProjectWizardPageJavaSettings
• SymbolDefinitionsImportWizardPage
• DeviceManagementPreferencePage
• J2MEOTAPreferencePage
• J2MEPreferencePage
• NewJ2MEProjectPreferencePage
• ObfuscationPreferencePage
• PackagingPreferencePage
• PreprocessPreferencePage
• PreverificationPreferencePage
• SymbolDefinitionsImportWizard
• MTJUIPreferenceInitializer

 

Preferences from JavaCore are used by:

• SourceViewerInformationControl

 

 

Questions:

 

In MTJUIPreferenceInitializer, there is a method initializeDefaultPreferences() with the comment “Synchronize the preferences between the core and UI plug-ins”. It appears that this method will cause MTJCorePreferenceInitializer.initializeDefaultPreferences(prefs) to be called twice. What is the purpose of this synchronization?

 

I don't know about calling it twice, but this was the standard way to initialize default preferences in the earlier Eclipse support before IEclipsePreferences came along.  An "initializer" was called by the platform to set the default values into the Preferences objects.  This is now handled by the "default scope" preferences as you've been seeing.

IEclipsePreferences Default scope should apply to defaults. Are Instance scopes most appropriate for project settings and Configuration scopes most appropriate for MTJ preferences settings?

 

In fact, there is actually a project-scope as well.  There are multiple implementations of the IScopeContext interface:

- org.eclipse.core.runtime.preferences.DefaultScope - For default values.  Searched if there isn't a definition in another scope.
- org.eclipse.core.resources.ProjectScope - Preferences that are tied to a specific project
- org.eclipse.core.runtime.preferences.InstanceScope - This is the same as a workspace-scoped preference
- org.eclipse.core.runtime.preferences.ConfigurationScope - These preferences apply to *all* instances

In our existing code, are we using the deprecated Preferences for all MTJ workspace-level preferences and IEclipsePreferences for project-level preferences? Is it a simple case of replacing the use of Preferences with Configuration scope IEclipsePreferences?

 

 

At least in EclipseME days, there were two levels of preference storage.  Project-level and Workspace (instance) level.  I don't know that there were many (any?) configuration-scoped values.  So... In the end, the mapping should be pretty straightforward... Anything at project-scope should be mapped to ProjectScope and everything else should be at InstanceScope.  Any default values in the initializer should to into DefaultScope.

 

 

Regards,

Jon

 

---

Senior Software Developer, Eclipse Tools

Research In Motion

905-629-4746 x15333 / Mobile: 519 500-23167

jdearden@xxxxxxx

 

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