Skip to end of metadata
Go to start of metadata

You are viewing an old version of this page. View the current version.

Compare with Current View Page History

« Previous Version 53 Current »

Please use this page to document all the ideas and wishes you'd like to see in Groovy.


Non-breaking Switch Enhancements

Objective: get rid of a lot of if then else statements; eliminate unnecessary syntax; no impact on "java-like" groovy code.

Multiple parameters/targets

Alternate '->' Syntax, Optional 'default', Assign Result

Combine "Multiparameter" and "Alternate Syntax" with Abbreviated form in Closures

Here the '->' form implies 'return' instead of 'break' (same result at this level)

Another example:

Here you can see the special "case" is executed when the list size is less than 2, otherwise it looks like a normal closure.

The above proposal does not break any existing code, does not add any keywords, does not break compatibility with java ("paste java in to groovy and it work", etc).

The multi-parameter switch statement and '->' in a switch so it has a result is where the core of the work would be. The 'case' statement on a closure definition for pattern matching like capability is just syntactical sugar.

--krsmes (Apr 2010)


  • New function for integers to reverse bits.
  • Concatenate string with null object.  'Test'+null will produce 'Test'.
  • Function/Global method 'NVL'. This method avoid null/empty string value of object. E.g. NVL(null,'Test')='Test' and NVL('','Test')='Test'
  • Joining of list without null elements.

         e.g. [null,'Hello','world',null].join(' ') will produce 'Hello world'

  •  Simple and Robust way of executing external processes instead of using ProcessBuilder. Make the convenient string.execute() handle blocked IO streams / threading so users are not required know or understand about ProcessBuilder
  • More Enumerable methods for lists, arrays and maps (like map, pluck, invoke, ...)
  • Make logical operators (||, &&...) return the value instead of the boolean equivalent
    eg.

  • Make map creation more versatile Add constructors that allow creation of a map from 2 collections "HashMap(keys, values)" or a list of entries "HashMap(itemlist)".
  • Make a list and create an auto mapping:

          eg.






  • would like methods to return more than one return value (a la ruby)

Property reference operator

Groovy 1.0 already has the method reference operator:




However we do not have anything similar for properties. i.e. we should be able to get a reference to a wrapper object for any object property, and be able to get and set the property via the reference, and get the original property name and owning bean:




This would be useful in Grails and other apps that need the user to specify in their code a reference to another propery, for example in GORM declaring the list of "embedded" properties:

class AddressBookEntry

Property access in groovy is not problematic using GPath or subscript operator anyway, so this may not seem so useful. However if we could get some compile-time checking of the validity of the property that would be a nice win. Perhaps combining with the @ operator:




Altho a tad heiroglyphic, this would allow the compiler to ensure that "home" and "work" do exist as declared properties on the class or its ancestors, and hence fail fast.

named parameters everywhere

the proposal is that for functions defined inside groovy or where the debug information is availlable can be called with the map construct to provide named parameter calling everywhere 




this feature would largely improve general readability of code and imho very often enough information should be availlable to perform the matching (certainly for groovy functions, very often for java binaries with appropriate debug information)

smarter nulls

 




should print "hello" iso "hellonull"

variable constraints

Keep dynamic typing while adding real type safety with constraints on variables that all must be true.  Though not all these constraints are actually useful they are there for illustrative purposes.

Embedded XML

The programming language Scala has built-in support for XML. You can create something like this (taken from the Scala overview document):

 Decoupling of static and instance methods

 

Also taken from the Scala programming language. It doesn't have static methods. All the static methods should be placed in a singleton. Static members are not a part of instance variables, so you shouldn't have to declare them in the same class.

 New way of declaring Expando

Could be just like in annonymous types in C#. For example:

First Class Support for User-Defined Boolean Types

There is already quite good support for user-defined numeric data (e.g. classes that act like numeric data in expressions) using the current support for operator overloading.  But if one needs to define a class that operates in expressions like a Boolean, it can't be done.  The following changes would make this possible and these seem consistent with the overall idea and design of Groovy:

  1. Enable operator overloading for logical AND, logical OR, logical NOT. For logical AND and logical OR, the deferred evaluation of the right operand can be maintained by passing a Closure to the method.  The signatures might be something like this:

  2. Enable assignment operator overloading.  This is needed to allow a semantic like

    Note that overriding the assignment operator makes it significantly easier to replace numeric types too since one can handle cases like

    which is not possible today.

  3. Today due to "Groovy Truth" processing, any non-null object reference (that is not a Boolean) will evaluate to true.  To enable user-defined Boolean type data, Groovy Truth would need to be modified to optionally "unbox" a non-null object reference into a Boolean value if it has a booleanValue() method.  This would allow one to do something like this

    In such a case, the bool instance can be either false or true and can be directly used for control flow and other operations that normally expect a Boolean.
    With these changes, user-defined boolean replacement classes would get first-class support in the language.

 Smalltalk-like syntax for methods

 I've seen that in Groovy 1.5 it was possible to avoid using parenthesis when calling a method. It was made to simplify the reading in a more natural way...  

Nevertheless I'm not sure that the goal is  today reached... The groovy syntax was primarly  settled to make the step from Java easier for java coders...Along the versions, some syntactic sugar was added to fulfill new needs...to reach the point where going from jav to groovy is not so straightforward... Personnaly it is not an issue, but I would like to point out that if we differ more and more from java, why not adopting a syntax which is more accurate and simpler?

Personnaly, I find the Smalltalk syntax simpler and more elegant... I think that we could add some syntactic "tournures" of Smalltalk in Groovy 2.0, especially for defining new methods....

definition example : 

or

 or better

use example :

Expect for Groovy

 

What is expect?

Expect has been already ported to other languages:

Expect for Perl

Why can't we have it built in?

My proposal:

Expect for Groovy 

Automatic constructor for immutable Groovy Beans

Automatically create a constructor for all final properties of a Groovy Bean.

And then:

There should be no setters generated, and not be possible to change the values of id or name after object creation.

It would be even better if you could use named parameters to the constructor as well:

  • No labels