I have the following type in my grammar:
TestSuite:
'TestSuite:' name = ID
'Type:' type = SuiteType;
enum SuiteType:
INTERNAL='1' | EXTERNAL='2';
I would like to read an xml file whenever the property gets a (new) value since I use the contents of that xml file for validation and content completion. Depending on the value of the property, the xml that will be read will be different.
How would you trigger an action that would read the value of a property of a type from the runtime environment's DSL instance?
You could maybe try adding an EMF Adapter to all TestSuite instances such that upon a Notification that changes your 'type' feature to a particular value, the XML file of your choice is read and acted upon.
this blog post seems to do the trick: at the end of the linking phase, an Adapter (this is EMF vocabulary, basically a Listener) can be registered for your TestSuite instances.
Then in your Adapter implementation, you can filter whether you need to react using the methods of Notification such as getFeature().
Since you mention you want to do this for content completion and validation, you may need to do all of this in the scoping / validation phases of Xtext. You will probably have a bit of "lag" upon hitting ctrl+space for auto-completion if your IDE needs to find and parse your XML file, but that's to be expected I guess...
Related
I've just spent 20 hours in learning about the basics of Dart language, but when I find the # prefix in an open-source Dart program such as here, which I found that most programs use, I wonder what the # directive do in those programs...
For your information, the official documentation says the following:
Metadata
Use metadata to give additional information about your code. A metadata annotation begins with the character #, followed by either a reference to a compile-time constant (such as deprecated) or a call to a constant constructor.
Three annotations are available to all Dart code: #deprecated, #override, and #proxy. For examples of using #override and #proxy, see the section called “Extending a Class”. Here’s an example of using the #deprecated annotation:
However, what "additional information" does the # directive add to the code? If you create an instance by writing the following constructor
#todo('seth', 'make this do something')
, instead of the following constructor, which is the default:
todo('seth", 'make this do something')
, what is the benefit I can get from the first constructor?
I've got that using the built-in metadata such as #deprecated and #override can give me an advantage of being warned in running the app, but what can I get from the case on the custom #todo, or the aforementioned linked sample code over Github?
Annotations can be accessed through the dart:mirrors library. You can use custom annotations whenever you want to provide additional information about a class, method, etc. For instance #MirrorsUsed is used to provide the dart2js compiler with extra information to optimize the size of the generated JavaScript.
Annotations are generally more useful to framework or library authors than application authors. For instance, if you were creating a REST server framework in Dart, you could use annotations to turn methods into web resources. For example it might look something like the following (assuming you have created the #GET annotation):
#GET('/users/')
List<User> getUsers() {
// ...
}
You could then have your framework scan your code at server startup using mirrors to find all methods with the #GET annotation and bind the method to the URL specified in the annotation.
You can do some 'reasoning' about code.
You can query for fields/methods/classes/libraries/... that have a specific annotation.
You acquire those code parts using reflection. In Dart reflection is done by the 'dart:mirrors' package.
You can find an code example here: How to retrieve metadata in Dartlang?
An example where annotations are regularly used is for serialization or database persistence where you add metatdata to the class that can be used as configuration settings by the serialization/persistence framework to know how to process a field or method.
For example you add an #Entity() annotation to indicate that this class should be persisted.
On each field that should be persisted you add another annotation like #Column().
Many persistence frameworks generate the database table automatically from this metadata.
For this they need more information so you add a #Id() on the field that should be used as primary key and #Column(name: 'first_name', type: 'varchar', length: 32) to define parameters for the database table and columns.
This is just an example. The limit is you imagination.
When using [Dynamics] [AX] is there a system function that can be used
to determine which module the user was in when the program was called?
I want to execute different X++ lookup code for employee,
for the ProjJournalTable form, but this would
be a different employee-list depending on which module is calling
the form. Hope that's clear! - Maeve
There is no concept of "module" in the execution context of a form or report. Therefore there is no system function to return that.
How to get around context dependant behaviour, where the behaviour depends on the caller?
The usual method in say a lookup form is to inspect element.args() for one of:
element.args().dataset() and/or element.args().record()
element.args().parmEnumType() and element.args().parmEnum()
element.args().parm()
element.args().caller()
element.args().parmObject()
Take a look on the form LedgerAccountLookup for example, you can find many more by searching for "args" in form methods named "init".
I'm writing a Groovy script (as part of a Grails plugin) and I want to get a list of properties for a GrailsDomainClass that a user of my plugin might define. I can do this using domainClass.properties (where domainClass is a GrailsDomainClass).
However, suppose a user has the grails domain class:
class Example {
String name
static constraints = {
}
def getSomeNonExistingProperty(){
return "Not-a-real-property"
}
}
In this case, domainClass.properties returns a list with both name and someNoneExistingProperty
I understand that this is because of Grails is generating a read-only property on-the-fly for use where someone has a getBlah() method. That's great, but in my script I want to perform some actions with the "real" properties only (or at least non read-only properties).
That is, I would like some way of distinguishing or identifying someNonExistingProperty as a read-only property, or, alternatively, as a property generated by Grails and not entered explicitly as a field in the domainClass by the user of my plugin.
I've looked at the GrailsDomainClassProperty Class and it has a range of methods providing information about the property. However, none of them appear to tell me whether a property is read-only or not, or to allow me to distinguish between a field defined in the domainClass and a field created on-the-fly by Grails as a result of a "getSomeNonExistingProperty()" method.
Am I missing something obvious here? Is there a way of getting a list of just the explicitly user-defined fields (eg name, in the above example)?
I believe transient properties are what you are trying to exclude
I've run into this problem a few times, and instead of trying to work around it I typically just end up renaming my getX() method. It's probably the easiest option.
Edit:
Alternatively, I wonder if you could use reflection to see which methods are defined on the class, and while iterating over your properties see if the property has an explicit getter defined, and omit it. I'm not very familiar with reflection when it comes to Groovy and Grails, especially with the dynamic methods, but it's a possible route of investigation.
I am trying to make a taglib to represent an object (to read and display at the UI). When creating an object (save method in the controller), I see the domain class and association are created by the auto assignment of parameter
def Book = new Book(params)
It also maps complex types (for eg: joda time). I wonder about the naming convention necessary to facilitate this mapping. Out of curiosity, can someone also point where in the grails source code I could see how grails handles this mapping. I'm still learning Spring and probably this would be a good exercise.
Thanks,
Babu.
AFAIK the naming conventions are rather straightforward. If there's a field params.foo and the object you are binding to has a field foo, it will bind the value, assuming the type conversion works properly. If there's a params.bar.id set with an Long value and your object has a complex property of type Bar, it will lookup this instance and inject it.
If you need more control over the binding process, you might want to use bindData.
If you are interested into the details of the binding process, have a look at Java's PropertyEditor as this is what is being used in the background. I wrote a blog post on how to create and register PropertyEditors a while ago, maybe it helps you getting started with that stuff.
I've created a new custom JSON codec for OpenRasta which works fine.
I need to pass arguments to the codec's write method when the handler is executed but cannot find any documentation on how to do it.
I notice in the implemented WriteTo method, there is a string[] codecParameters parameter, however no idea how to pass them in.
Anyone come accross this problem before? Thanks
the codec parameters are per-request. They're intended to be used together with (for example) the PathSegmentAsParameterUriDecorator.
For example, if you enable that decorator, the path /resource;segment will be treated as /resource by openrasta, and a parameter will be created with the "segment" value, and passed to the codec.
If you wish to pass information to the codec from the handler, there's nothing there, as architecturally it goes against the design of OpenRasta, which specifically prevents handlers and codecs from talking to each others.
If you wish to pass configuration data to your codec, you use the Configuration property from the ICodec interface, which will be filled with whatever object you have provided at configuration time.
You provide the configuration object either through the paramter in the .TranscodedBy(object configuration) method, or if you do custom registration using the configuration metamodel, bu adding the configuration to your Configuration property on CodecModel (which incidently is used in the ResourceModel object created by the fluent API).
Do you have a specific scenario I can help with?