I want to generate a custom named constructor in Dart.
I have many dto class to implement and each should provide a named constructor like: ClassName.fromMap().
For example for this class:
class Student {
final String name;
final int age;
}
The generated constructor should be:
Student.fromMap(Map<String, dynamic> map) :
name = map['name'],
age = map['age'];
How can I retrieve the list of the field of my current class as strings? Is that even possibile?
Of course I can have a variable number of fields.
My template looks like:
$CLASS$.fromMap(Map<String, dynamic> map) :
$INITIALIZATION_LIST$
binding $CLASS$ to dartClassName().
Now I'd like to bind $INITIALIZATION_LIST$ to something like:
getClassFieldList().forEach((fieldName) => "$fieldName = map['$fieldName']")
Can I achieve something like that?
There is no way to retrieve a list of Dart class fields using predefined live template functions. You can try developing your own template macro for this. See https://intellij-support.jetbrains.com/hc/en-us/community/posts/206201699-create-a-new-expression-for-a-live-template-for-actionscript for some hints.
Existing live template functions implementations can be found at https://github.com/JetBrains/intellij-community/tree/master/platform/lang-impl/src/com/intellij/codeInsight/template/macro.
You can also try using Structural Search and Replace instead of live template
Related
I'm just starting to learn kotlin and ran into a problem:
I have a Person class that has two fields
-age (Int data type)
-name (data type String)
there is also a oldUp function where I pass a Person object and increment the object's age field by 10.
Before the end of the program ** I want to display the age of the object that was passed to oldUp **
However, age is not shown.
my code:
class Person(var name: String, var age: Int){
}
fun growOld(human: Person){
human.age+=10
}
fun main(args: Array<String>) {
var human = Person("Kitty",6)
growOld(human)
println(human)
}
If you want to print the age, you can just write: println(human.age).
In your example it might be cleaner to add the growOld method to your class so you can call it on the object. For example:
class Person(var name: String, var age: Int){
fun growOld() {
this.age += 10
}
}
fun main() {
var human = Person("Kitty", 6)
println(human.age) // prints 6
human.growOld()
println(human.age) // prints 16
println(human.name) // prints Kitty
}
The problem is you're trying to print the human object itself. Under the hood, this calls its toString() method - every class has one of these, because it's defined on the type all classes derive from. If you don't override it and provide a nice way to "pretty print" your object, it'll use the default implementation, which is basically a reference to the object in memory.
A lot of classes you use have a nice toString() implementation, e.g. if you print a List you get ["something", "that", "looks", "like", "this"]. But that behaviour needed to be coded in - and you need to do that for your Person class too!
So you can override the default implementation like this:
override fun toString(): String {
// return a String here
}
override means you're taking an existing function and writing your own version of it to use instead - if this doesn't match an existing function you can override, you'll get an error. You'll also get an error if you don't use the override keyword for a function that looks exactly like an existing one in a supertype - it's just to make sure you don't accidentally do the wrong thing. In IntelliJ you can do Ctrl+O to override existing functions if you like.
So you could do something like this:
// inside your Person class
override fun toString(): String {
return "Name: $name, age: $age"
}
and then when you use it in a print statement, or in a string (like "Details: $person" or val details = "Details: " + person) it will call that toString() method and get the string you produced.
Another way to approach this is to use a data class:
data class Person(var name: String, var age: Int)
A data class is a special kind of class where all your "data" goes in the constructor (as properties, either val or var), and then you get some boilerplate stuff for free which uses those properties (and only those properties). Things like an equals() and hashCode() implementation that uses that data - and the relevant thing here, it gives you a toString() implementation that pretty prints name and age. Try it out!
Data classes can be really handy for simple data objects like you have here - but in normal classes, overriding toString() yourself is the general way of doing things. And you can still override a data class's toString if you want - sometimes you might want a more complex representation, or nice formatting, or you might want to only include some properties and ignore others. You're in control of how it prints itself!
And if you just want to print the age property, or print anything at all using the data in your object, then you just need to do what Robin's answer says. You don't need a toString() implementation at all for that (and since this is how you usually use objects, often you won't need to write a toString for your own classes at all)
I have set of java classes and I want to refer them in the DSL which I am trying to edit using Xtext grammar. e.g. There is a class Employee :
class Employee{
String name;
double salary;
String organisation;
String status;
}
Now in my DSL I wish to use them. Hence when user is trying the name he should get these tree attributes as help. e.g. DSL i will like to trite like this:
employee.salary > 100000 then employee.status='GOLD'
My question is when i am typing the name such as employee than all the three attributes should be available to user as context help.
I've created a method like so:
void myMethod(Map kwArgs, def myParam)
{
println kwArgs.firstName
println [kwArgs.lastName, "Wilcox"].find()
// ^^^ if lastName named parameter not specified, "Wilcox"
....
}
Now comes the time to document this method with GroovyDoc. Part of it is easy
/**
myMethod rules the world
#param myParam something something
But how do I document the named parameters? (Likewise, how can I specify that the lastName parameter has a default? (ie is there some metadata I can set or just make that explicit to the reader in the English description?)
But how do I document the named parameters?
Unless you are considering writing a customer doclet or similar, I think you will just document them as text in the comment.
I'm trying to display XmlElement's attributes in Xceed PropertyGrid. For that purpose I defined custom wrapper class. It wraps XmlElement, iterates over XmlAttributes and creates custom PropertyDescriptor for each XmlAttribute. All "virtual" properties' type is String. All works fine.
Now I want to have drop-down list of possible attribute values for every attribute that has restricted set of values. In Xceed's PropertyGrid, there is ItemsSourceAttribute for that. But it has to be applied as follows:
ItemsSourceAttribute(typeof(MyCustomItemsSource))
And here is the problem - I can not provide proper argument for MyCustomItemsSource constructor. What can I do about this?
It seems that there is another possibility - to define a TypeConverter, override GetStandardValues, and supply this converter to "virtual" property. But PropertyGrid just ignores this attribute.
How this simple task can be done with Xceed PropertyGrid?
Solved. I implemented custom editor
public class AttributeValuesEditor: Xceed.Wpf.Toolkit.PropertyGrid.Editors.ComboBoxEditor
{
protected override IEnumerable CreateItemsSource(PropertyItem propertyItem)
{
var property = propertyItem.PropertyDescriptor as XmlAttributePropertyDescriptor;
Debug.Assert(property!=null);
return property.GetCompletionValues();
}
}
Here, the context is passed into method in the form of PropertyItem. Now it is possible to differentiate between different attributes and return appropriate items.
Using Automapper, how do you handle the mapping of a property value on an object to an instance of a string. Basically I have a list of Role objects and I want to use Automapper to map the content of each "name" property to a corresponding list of string (so I just end up with a list of strings). I'm sure it has an obvious answer, but I can't find the mapping that I need to add to "CreateMap" to get it to work.
An example of the relevant code is shown below:
public class Role
{
public Guid Id{get;set;}
public string Name{get;set;}
...
...
}
// What goes in here?
Mapper.CreateMap<Role, string>().ForMember(....);
var allRoles = Mapper.Map<IList<Role>, IList<string>>(roles);
I love Automapper (and use it in a number of projects), but wouldn't this be easier with a simple LINQ statement?
var allRoles = from r in roles select r.Name
The AutoMapper way of accomplishing this:
Mapper.CreateMap<Role, String>().ConvertUsing(r => r.Name);