
h2(#NatureAndBuilder). OCL Nature and Builder Auto-Validation

The build of an OCL or OCL-containing source file validates the ource file and updates markers in the Problems View to identify issues that the user may care to address. Double-clicking on the Problems View Marker opens an
editor to faciltate fixing the problem.

The build validation occurs whenever a source file changes or is 'cleaned' and when the containing project
has the OCL nature configured.

If the Eclipse Workspace is configured to auto-build, the OCL builder runs automatically and so auto-validation occurs.

h3(#OCLbuilderConfiguration). Configuring the OCL Nature and Builder

The OCL Nature may be added or removed from a Project by selecting the project in an Explorer View and
invoking *Configure->Convert to OCL Project* or *Configure->Unconfigure OCL* from the context menu. Alternatively
the new Project Natures page may be used from the Project Properties page.

Configuing the OCL nature modifies the *.project* file to add the *org.eclipse.ocl.pivot.ui.oclnature* nature
and *org.eclipse.ocl.pivot.ui.oclbuilder*. The builder has an argument dictionaries to select file extensions
and file paths that are included or excluded by the builder.

bc.. 
<arguments>
	<dictionary>
		<key>disabledExtensions</key>
		<value>*,essentialocl</value>
	</dictionary>
	<dictionary>
		<key>disabledPaths</key>
		<value>bin/**,target/**</value>
	</dictionary>
	<dictionary>
		<key>enabledExtensions</key>
		<value>ecore,ocl,oclinecore,oclstdlib,uml</value>
	</dictionary>
	<dictionary>
		<key>enabledPaths</key>
		<value>**</value>
	</dictionary>
</arguments>
p. 

The default configuration enables validation of *ecore,ocl,oclinecore,oclstdlib,uml* extensions and disables all other extensions, redundantly adding an explicit *essentialocl* exclusion to make the syntax more obvious to a
casual reader. (*.essentialocl files may contain a single OCL expression, but since they lack any embedding within a model, they are not generally useful.)

The default configuration enables all paths except the *bin* and *target* paths where the Java builder or Maven builders may place copies of files that are not usually worth revalidating as distinct files.

The configuration in the *.project* file may be edited with a text editor; there is currently no dedicated user interface.

h3(#EcoreAndUMLautoValidation). Ecore and UML Auto-Validation

The EMF and UML projects provide no nature or builder and so Problems View markers for *.ecore and *.uml files
are dependent on the problems in the prevailing selection at the time of the preceding manual validation.

Since OCL may be embedded with *.ecore or *.uml files, the OCL nature and builder provide the option to auto-validate these files.

By default, your project has no OCL nature so no Ecore or UML auto-validation occurs.

If you choose to add the OCL nature, the default settings that enable *.ecore and *.uml auto-validation apply. The Problems View markers resulting from auto-validation are updated after a file is saved; any markers that the Ecore or UML editors created are replaced.

If you find that the auto-validation of some *.ecore and *.uml causes problems, perhaps because the reported
errors are not a concern for your usage, you may edit the *.project* file configuration.

You may remove *ecore* and/or *uml* from the *enabledExtensions* to suppress Ecore and/or UML auto-validation completely.

You may add individual files or file patterns to the *disabledPaths* to be more selective about disabling
auto-validation.

h3(#NoNature). Building on pre-Photon / 2018 releases

The OCL builder and nature are new in the Eclipse OCL 2018 release (Photon). They comply with the standard Eclipse idiom.

In earlier releases, the EMF idiom was followed whereby Problems View markers were created by their save action
of an appropriate editor. Problems in files that had not been saved were often not visible and so diagnosis
only occurred when some consuming application complained..