> Le 2015-10-28 à 21:40, Edinson E. Padrón Urdaneta
> <edinson.padron.urdan...@gmail.com> a écrit :
>
> I'm sorry mate. That happens when you code at midnight in a polluted
> groovysh. Try this out:
>
I don’t know what you are talking about ;-)
> def check(condition) {
> // Define and initialize a new map
> def map = [:]
>
> // Replace the `is` method from the map's metaclass
> map.getMetaClass().is = { bool ->
> println "checking if $condition yields $bool, with 'is'"
> }
>
> // Return the map
> map
> }
>
Brillant ! I have to say I'm surprised that `map.getMetaClass().is = ...` only
changes that map's metaClass, i.e. I expected it to change the `metaClass`
instance of the `Map` class, not the `metaClass` instance of a (single) `Map`
instance.
I wonder if this is an accident or designed that way ?
If it is by design, then that's very good for the purpose of a dsl as 1) `is`
can then be used, 2) with your technique, the metaclass manipulation is local
to the Map instance created in the chained method definition, therefore I don't
have to compromise on hiding Groovy to my DSL (as Jason explained).
In summary, to support the command expression
every 'member' of 'family' is 'adult'
my chained method definition is :
def every(member) {
[of: { what ->
def map = [:]
map.getMetaClass().is = { value ->
println "every - of - is : $member, $what, $value"
}
map
}]
}
Running it yields the expected result :
every - of - is : member, family, adult
Granted, writing the chained method definition is a little more tricky, partly
because one have to be careful of dynamic scoping for `member` and `what`, but
the net result is very nice.
Thank you very much for your ideas !
Marc
>
> On Wed, Oct 28, 2015 at 8:31 PM, Marc Paquette <mar...@mac.com
> <mailto:mar...@mac.com>> wrote:
> Your suggestion seemed promising, but I can’t make it work :
> 1) `map.metaClass` is null
> 2) `map.getClass().metaClass.is <http://metaclass.is/> = null` or
> `Map.metaClass.is <http://map.metaclass.is/> = null` does not remove the `is`
> method
> 3) `map[is]` gives `Caught: groovy.lang.MissingPropertyException: No such
> property: is for class: …`
>
> I am curious, you said « but it works », what version of groovy (groovy
> --version) did you use ?
>
>
>> Le 2015-10-28 à 01:08, Edinson E. Padrón Urdaneta
>> <edinson.padron.urdan...@gmail.com
>> <mailto:edinson.padron.urdan...@gmail.com>> a écrit :
>>
>> If you want to use `is` in your DSL you could try:
>>
>> def check(condition) {
>> // Define and initialize a new map
>> def map = [:]
>>
>> // Remove the `is` method from the map's metaclass
>> map.metaClass.is <http://map.metaclass.is/> = null
>>
>> // Add the key-value pair we care for the DSL
>> map[is] = { bool ->
>> println "checking if $condition yields $bool, with 'is'"
>> }
>>
>> // Return the map
>> map
>> }
>>
>> I don't know if the above follows good practices or at very least is a good
>> idea (remember that I'm very new) but it works.
>>
>>
>> On Wed, Oct 28, 2015 at 12:19 AM, Edinson E. Padrón Urdaneta
>> <edinson.padron.urdan...@gmail.com
>> <mailto:edinson.padron.urdan...@gmail.com>> wrote:
>> Well, I'm very new to groovy so I could be very wrong but `is` is a method
>> of `GroovyObjectSupport`, so maybe you are invoking that method in your DSL
>> without knowing that.
>>
>> On Tue, Oct 27, 2015 at 10:47 PM, Marc Paquette <mar...@mac.com
>> <mailto:mar...@mac.com>> wrote:
>> Playing with DSL here (going through chapter 19 of « Groovy In Action,
>> second edition », well worth the read). It seems that one cannot use the
>> word ‘is’ to build a command chain dsl, but ‘IS’ or ‘Is’ or ‘iS’ are ok… Or
>> is it something I’m doing wrong ?
>>
>> ```
>> [marcpa@MarcPaquette dsl]$ groovy --version
>> Groovy Version: 2.4.3 JVM: 1.8.0_60 Vendor: Oracle Corporation OS: Mac OS X
>> [marcpa@MarcPaquette dsl]$ cat chainWithLowerCaseIsFails.groovy
>> def check(condition) {
>> [is: { bool ->
>> println "checking if $condition yields $bool, with 'is'"
>> },
>> IS: { bool ->
>> println "checking if $condition yields $bool, with 'IS'"
>> }]
>> }
>>
>> cond = (1<2)
>> check cond is true
>> check cond IS true
>> [marcpa@MarcPaquette dsl]$ groovy chainWithLowerCaseIsFails.groovy
>> checking if true yields true, with 'IS'
>> [marcpa@MarcPaquette dsl]$
>> ```
>>
>> Marc Paquette
>>
>>
>>
>
>
