Eclipse Community Forums: Sirius » creating services with lambda arguments

Help

Home

Home » Eclipse Projects » Sirius » creating services with lambda arguments

Show: Today's Messages :: Show Polls :: Message Navigator

creating services with lambda arguments [message #1861318]

Thu, 05 October 2023 11:19

Tom Westbury

Messages: 11
Registered: December 2022

Junior Member

Hi, I am writing a few helper services for use in my sirius VSM and I was wondering if it is possible to write services that take lambdas as arguments so as to create a toolbox of useful generic services.

Some of the base AQL services in org.eclipse.acceleo.query.services use the type LambdaValue from org.eclipse.acceleo.query.runtime.impl but I am unable to find the source for this to understand how the class works.

Any help with working this one out would be greatly appreciated,

Many thanks,

Tom

Report message to a moderator

Re: creating services with lambda arguments [message #1861440 is a reply to message #1861318]

Thu, 12 October 2023 13:24

Pierre-Charles David

Messages: 705
Registered: July 2009

Senior Member

The sources of LambdaValue is visible here: https://github.com/eclipse-acceleo/acceleo/blob/master/query/plugins/org.eclipse.acceleo.query/src/org/eclipse/acceleo/query/runtime/impl/LambdaValue.java
Though I'm not sure it helps.

It's the runtime type of "code blocks" in AQL expression, as in:

Sequence{'a', 'b', 'c'}->collect(str | str.toUpper())

"Sequence{'a', 'b', 'c'}" evaluates to a Java List, and "str | str.toUpper()" into a LambdaValue, so AQL invokes the "collect(List<?> sequence, LambdaValue lambda)" Java service method defined here: https://github.com/eclipse-acceleo/acceleo/blob/master/query/plugins/org.eclipse.acceleo.query/src/org/eclipse/acceleo/query/services/CollectionServices.java#L596 with the list value as "sequence" and a LambdaValue representing the code block "str | str.toUpper()" as "lambda".

I've never tried it myself, but it should be possible to use the same patterns in your own Java services.
AFAIK, the ones AQL defines in its standard library like in CollectionServices have no special treatment/super-power; it's just that they are available by default.

EDITED: Actually it looks like the AQL parser will only accept this kind of code blocks (and produce LambaValue for them) for a fixed set of services (collect being one of them): https://github.com/eclipse-acceleo/acceleo/blob/079024efac839526674ae37876437037fe5b1f9c/query/plugins/org.eclipse.acceleo.query/src/org/eclipse/acceleo/query/parser/Query.g4#L71. So it seems that it is not possible to use this pattern for your own services.

Pierre-Charles David - Obeo

Need training or professional services for Sirius?
http://www.obeodesigner.com/sirius

[Updated on: Thu, 12 October 2023 13:33]

Report message to a moderator