javierfernandes
commented
8 years ago Yes. There are basically two aspects of this.
One is a bug. Seems like the scope is not correctly delimited for cross-references (well not actually cross files, but ..). A var inside a try shouldn't be available to be used anywhere else outside of the try. We don't have that, and that's why the checker is not reporting that problem. Then somehow the used/unused algorythm messes around, but just a side-effect.
Then on the other hand there's the runtime semantic of wollok. You see on this side of wollok the runtime environment is flexible, and resembles to dynamic languages. If there was a syntax to declare you could even do monkey patching and add methods or remove methods, / variables etc. Just that we didn't want that in the language. But the interpreter ""could"" support it.
This is low-level but the way the interpreter works it that when a var declaration is found it will add it to the current scope. Seems like in this case the scope is associated with the whole method. So the first try puts "x" in the method scope, then further tries can access them.
We create static checks in order to minimize the number of runtime errors. But there is one, for example when you try to access a variable which is not currently in the scope.
Anyway, just notes on the impl. At the end we need to go to the ScopeProvider classes and review/write some definition to delimit the scope of the WTry construction.
Regards
On Wed, Mar 9, 2016 at 2:54 PM, Franco Leonardo Bulgarelli < notifications@github.com> wrote:
Hi!
While implementing the wollok mumuki runner console, I wrote the following code:
program mumuki { try { var x = 1 } catch e : Exception { } try { x += 1 } catch e : Exception { } try { x += 1 } catch e : Exception { } console.println('=> ' + (x).toString()) }
Although I may look contrived, I actually need to write something like that in order to recreate a program state, by executing previous lines (1..3) before I actually execute the console statement x. And I need to ensure that such lines do not abort the program flow, so I am using try-catch's.
The program above works, and outputs the following line:
franco@xinaiu:~/Downloads/wdk$ ./bin/winterpreter.sh other.wpgm /home/franco/Downloads/wdk/other.wpgm:2:29 WARNING Unused variable => 3
But, as you can see, it generates an strange warning Unused variable. And I can figure out why: try blocks, like most Java like languages - introduce a new scope, so var x = 1 has no effect.
But this is inconsistent with the runtime behavior, because the program executed correctly.
So, either the checker is too strict, or the runtime is too tolerant. How should it actually work?
— Reply to this email directly or view it on GitHub https://github.com/uqbar-project/wollok/issues/612.
flbulgarelli
alete89
fdodino
npasserini
Hi!
While implementing the wollok mumuki runner console, I wrote the following code:
Although I may look contrived, I actually need to write something like that in order to recreate a program state, by executing previous lines (1..3) before I actually execute the console statement
x. And I need to ensure that such lines do not abort the program flow, so I am using try-catch's.The program above works, and outputs the following line:
But, as you can see, it generates an strange warning Unused variable. And I can figure out why: try blocks, like most Java like languages - introduce a new scope, so
var x = 1has no effect.But this is inconsistent with the runtime behavior, because the program executed correctly.
So, either the checker is too strict, or the runtime is too tolerant. How should it actually work?