Named result variables

[Robert Field]

Keep in mind I'm open to any solution.

Let me frame my idea as a strawman so it is easier to shoot arrows at :-)

Think: source code transformations that IDEs sometimes do.
So, in this case say, ...
You type in a complex expression expr. Then you press ctrl-V. The tool 
generates the type typedecl and an equals sign and sticks the cursor 
between them so you can type the variable name:

       typedecl. |   = expr:

Where | represents the cursor position.

Jan can tell me if this is even something jline can do.

The idea is, like tab, you type characters which don't correspond to valid 
Java, but what you see is valid.

Of course what character is typed to initiate this is arbitrary.

Ideas...

-Robert



On October 29, 2015 11:17:24 PM Robert Field <robert.field at oracle.com> wrote:

> Thanks Cay  putting this out for discussion, would love to come up with 
> some nice solution for this.  I would like to avoid something that 
> straddles the snippet and command worlds which are now distinct.
>
> I don't think I expressed my idea very clearly -- mostly because it isn't 
> at all clear to me ;-)
> What I was thinking was something vaguely tab completion like, in that you 
> wind up looking at a well formed snippet not all of which you explicitly 
> typed. But not literally a tab nor completion.
>
> Thanks,
> Robert
>
>
> On October 29, 2015 6:50:46 PM Cay Horstmann <cay at horstmann.com> wrote:
>
>> When I teach, I like to use jshell for quick demos. I might predefine
>>
>> <T> Set<T> setOf(T... values) { return new
>> TreeSet<>(Arrays.asList(values)); }
>>
>> and then construct two sets:
>>
>> Set<Integer> set1 = setOf(1, 2, 3);
>> Set<Integer> set2 = setOf(2, 3, 5);
>> set1.removeAll(set2)
>>
>> Except, that's a lot of typing, so I don't do that. I do
>>
>> setOf(1, 2, 3);
>> setOf(2, 3, 5);
>> $1.removeAll($2)
>>
>> Note the absence of types. The $n are automatically typed.
>>
>> But I lose track of those $n prettty soon. It would be nice if i could
>> name them.
>>
>> I brought this up at the Java One presentation and suggested
>>
>> /var set1 $1
>>
>> or
>>
>> /var set2
>>
>> to name the last $n.
>>
>> Robert thought that was a bit too much like inventing a new langauge
>> feature and suggested that one might be able to solve this with tab
>> completion instead.
>>
>> I thought about this a bit and couldn't come up with a compelling way.
>> Right now, when one hits Tab on a blank line, one is offered a
>> collection of well over 400 possible completions (types, packages,
>> classes, $ variables). Using that to get to something like Set<Integer>
>> or TreeMap<String, TreeSet<Integer>> isn't satisfactory.
>>
>> Does anyone else think that an easy way of naming results is worthwhile?
>> Any ideas on what the user interface should be?
>>
>> Cheers,
>>
>> Cay
>>
>>
>> --
>>
>> Cay S. Horstmann | http://horstmann.com | mailto:cay at horstmann.com