I'm writing some code with Slick and I'd like to be able to print the "Slick Query Tree" - is it possible somehow?
I assume you want to see the abstract syntax tree for queries?! You can watch this movie: http://youtu.be/THlvR9bXHIc - it is also referenced at "http://slick.typesafe.com/docs/" below "Screencast 1: Introduction to the query compiler".
AFAIK you can use method toNode and nodeChildren in your own slick code to recursively traverse the AST.
We log them.
See Slick logging with slf4j-simple
See the available loggers here https://github.com/slick/slick/blob/master/common-test-resources/logback.xml
You'll need to look at the compiler ones.
Related
How does one convert an ASTNode (or at least a CompilationUnit) into a valid piece of source code?
The documentation says that one shouldn't use toString, but doesn't mention any alternatives:
Returns a string representation of this node suitable for debugging purposes only.
CompilationUnits have rewrite, but that one does not work for ASTs created by hand.
Formatting options would be nice to have, but I'd basically be satisfied with anything that turns arbitrary ASTNodes into semantically equivalent source code.
In JDT the normal way for AST manipulation is to start with a basic CompilationUnit and then use a rewriter to add content. Then ASTRewriteAnalyzer / ASTRewriteFormatter should take care of creating formatted source code. Creating a CU just containing a stub type declaration shouldn't be hard, so that's one option.
If that doesn't suite your needs, you may want to experiement with directly calling the internal org.eclipse.jdt.internal.core.dom.rewrite.ASTRewriteFlattener.asString(ASTNode, RewriteEventStore). If not editing existing files, you may probably ignore the events collected in the RewriteEventStore, just use the returned String.
I would like to change the behavior of menhir's output in follwoing way:
I want it to look up all grammatical alternatives if it finds any, and put them in a list and get me back this ambigouus interpretation. It shall not reduce conflicts, just store them.
In the source code of menhir, it seems to me, that I have to look in "Engine.ml". The resultant syntactically determined token comes in a variant type item "Accepted v" as a state of a checkpoint of the grammatical automaton. This content is found by a function "accept env prod" before, that is part of a bundle of recursive functions, that change the states.
Do you have a tip, how I could change these functions to put all the possible results in the list here and proceed as if nothing happened? Or do you think, that this wont work anyway?
Thanks.
What you are looking for is a GLR parser generator (G is for generalized). Menhir is not such tool, and I doubt you could modify it easily to do what you want.
However, there is another tool that does exactly what you want: dypgen.
We would like to understand a couple of legacy job-dsl scripts but don't know what "slash operator" means in this context (as it cant be division):
def command = (shells.first() / command)
We have tried to look it up in several Groovy books but only found the trivial solution that it means 'division'.
It's an XML Node operation, to return a sub-node of a XML node, or create it if it doesn't exist. Probably the command node under the first of your shells nodes here.
Groovy allows operator overloading, so it is the same "division" operator, just redefined somewhat. This is common (but also controversial) in other languages allowing operator overloading, but does allow for richer DSLs.
Having had a quick look at (an old copy of) the JobDSL source, it seems that they're doing it using a class NodeEnhancement, notably this JavaDoc:
/**
Add div and leftShift operators to Node.
div - Will return the first child that matches name, and if it doesn't exists, it creates
...
**/
Hi there I would like to do something like this
tasks = session.query(User).filter(User.id == user_id).options(subqueryload_all(User.tasks)).filter(Task.title.like("%"+substring+"%")).one().tasks
so basically select all user tasks which title contains substring
Any ideas why my code is not working?
:) thanks
EDIT:
by not working I mean that it give a wrong result... it returns all User.tasks without applied filter
it seems like you're expecting the collection loaded by the subqueryload to be affected by the filter on Task. The eager loading options don't work this way; they are never impacted by the rest of the query. Read The Zen of Eager Loading for background.
in this case, you can either use a join with contains_eager or you can roll your own subqueryload using the disjoint eager loading recipe, which is the precursor to the subquery eager loading feature.
I was wondering about some best practices regarding extraction of selectors to constants. As a general rule, it is usually recommended to extract magic numbers and string literals to constants so they can be reused, but I am not sure if this is really a good approach when dealing with selectors in Capybara.
At the moment, I have a file called "selectors.rb" which contains the selectors that I use. Here is part of it:
SELECTORS = {
checkout: {
checkbox_agreement: 'input#agreement-1',
input_billing_city: 'input#billing\:city',
input_billing_company: 'input#billing\:company',
input_billing_country: 'input#billing\:country_id',
input_billing_firstname: 'input#billing\:firstname',
input_billing_lastname: 'input#billing\:lastname',
input_billing_postcode: 'input#billing\:postcode',
input_billing_region: 'input#billing\:region_id',
input_billing_street1: 'input#billing\:street1',
....
}
In theory, I put my selectors in this file, and then I could do something like this:
find(SELECTORS[:checkout][:input_billing_city]).click
There are several problems with this:
If I want to know the selector that is used, I have to look it up
If I change the name in selectors.rb, I could forget to change it somewhere else in the file which will result in find(nil).click
With the example above, I can't use this selector with fill_in(SELECTORS[:checkout][:input_billing_city]), because it requires an ID, name or label
There are probably a few more problems with that, so I am considering to get rid of the constants. Has anyone been in a similar spot? What is a good way to deal with this situation?
Someone mentioned the SitePrism gem to me: https://github.com/natritmeyer/site_prism
A Page Object Model DSL for Capybara
SitePrism gives you a simple, clean and semantic DSL for describing
your site using the Page Object Model pattern, for use with Capybara
in automated acceptance testing.
It is very helpful in that regard and I have adjusted my code accordingly.