<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html; charset=UTF-8" http-equiv="Content-Type"> </head> <body bgcolor="#ffffff" text="#000000"> Hi Jaromir, On 6/5/2021 10:04 AM, Jaromir Matas via Cuis-dev wrote: <blockquote cite="mid:BN7PR08MB384285A80F464E2B2CAFE41DEE3A9@BN7PR08MB3842.namprd08.prod.outlook.com" type="cite"> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <meta name="Generator" content="Microsoft Word 15 (filtered medium)"> <style></style> <div class="WordSection1"> Hi Juan, <o:p> </o:p> <o:p> </o:p> > Hi Jaromir, ><o:p> </o:p> > I've just pushed your latest to GitHub. I included a note with links to this email thread in #terminate. I also added the new tests; and your examples as a class method in Process, for future reference. <o:p> </o:p> You made my day, thanks :) It's been a great learning experience; I'd like to thank you for your valuable comments and feedback that helped me to stay on track. Also, I appreciate you keep Cuis' kernel simple and compact. </div> </blockquote> My pleasure! <blockquote cite="mid:BN7PR08MB384285A80F464E2B2CAFE41DEE3A9@BN7PR08MB3842.namprd08.prod.outlook.com" type="cite"> <div class="WordSection1"> <o:p> </o:p> I'd like to share some remarks: <o:p> </o:p> 1) you might ask why #complete:to: is defined in Process and not in ContextPart? It should, really, but I wanted to keep it the same as in Squeak for the moment :) </div> </blockquote> <o:p> </o:p> <o:p> Using the same code as Squeak is a good idea for areas in the system where we don't chose a different approach! </o:p> <blockquote cite="mid:BN7PR08MB384285A80F464E2B2CAFE41DEE3A9@BN7PR08MB3842.namprd08.prod.outlook.com" type="cite"> <div class="WordSection1"> 2) there's currently a discussion (Christoph) what semantics is the most appropriate for closing the debugger: If you encounter a fatal error or the debugged process is damaged too badly, using #terminate might be "too strong" and lead e.g. to an infinite recursion of debuggers etc. For such cases a "light" version od #terminate (#terminateLight) without completing the halfway through unwind contexts would probably be more appropriate. For the most severe cases even a Kill option without any unwinds might come in handy. I imagine e.g. using #terminate for the standard closing of the debugger's window and the light version of #terminate for an explicit Abandon button. </div> </blockquote> I think that [Abandon] should also do #terminate. And a new button [Kill] is preferable. (Maybe use the same button, but with [Shift], or a right-click menu, etc) Please don't call it "light" as it is actually stronger, because it does "more violence" to the process (meaning that the use of 'light' or 'strong' won't be obvious, and will have to be explained every time!). It is best to stick to standard nomenclature. Terminate (SIGTERM) as the default, usually safe way, and Kill (SIGKILL) as the last resort. These are the names used in Linux / Unix. <blockquote cite="mid:BN7PR08MB384285A80F464E2B2CAFE41DEE3A9@BN7PR08MB3842.namprd08.prod.outlook.com" type="cite"> <div class="WordSection1"> <o:p> </o:p> <o:p> </o:p> 3) I'd like to raise a question about non-local return's semantics during termination: <o:p> </o:p> **What takes precedence: a termination or a non-local return?** <o:p> </o:p> Squeak has a method `valueUninterruptably ^ self ifCurtailed: [^ self]` which in its comment says: "Even attempts to terminate (unwind) this process will be halted and the process will resume here. A terminate message is needed for every one of these in the sender chain to get the entire process unwound." <o:p> </o:p> It means Squeak authors originally intended to allow a process to escape its termination via a non-local return inside an unwind block but the implementation never worked. <o:p> </o:p> The alternative behavior is: termination takes precedence and doesn't allow a non-local return to route the computation outside the unwind block. This is the behavior of the current #terminate. <o:p> </o:p> I'd like to know your opinion about this matter; the new #terminate can be amended easily to allow for non-local returns take precedence over termination but I'm not sure it's really desirable - what do you think? <o:p> </o:p> <o:p> </o:p> Example: ``` p := [ [:exit | [Processor activeProcess suspend] "<-- terminate here" ensure: [exit value]] valueWithExit. Transcript show: 'escaped termination' ] newProcess resume. Processor yield. [p terminate] fork ``` Current implementation will not print anything and just terminate the process p because there are no unwind blocks except `[exit value]`. <o:p> </o:p> Originally, however, the non-local return inside `[exit value]` was intended for the process p to escape termination and continue executing, i.e. print 'escaped termination' and go on. </div> </blockquote> <o:p></o:p> <o:p> I have no opinion. So, I wouldn't change it unless a compelling argument appears. </o:p> <blockquote cite="mid:BN7PR08MB384285A80F464E2B2CAFE41DEE3A9@BN7PR08MB3842.namprd08.prod.outlook.com" type="cite"> <div class="WordSection1"> 4) One last comment FYI: #unwindTo: method under ContextPart in my opinion suffers with the same bug as #terminate used to, and could be fixed similarly (there are currently no senders however). Check this example: <o:p> </o:p> ``` p := [ [:exit | [Processor activeProcess suspend] "<-- unwind here" ensure: [exit value]] valueWithExit ] newProcess resume. Processor yield. p suspendedContext unwindTo: nil ``` <o:p> </o:p> It incorrectly produces the BlockCannotReturn error. If you do `p terminate` instead of `p suspendedContext unwindTo: nil`, it works as expected. </div> </blockquote> I guess a comment stating exactly what you say is enough, at least unless there is areal need for #unwindTo: If you are willing to write it, I'll be happy to integrate it. <blockquote cite="mid:BN7PR08MB384285A80F464E2B2CAFE41DEE3A9@BN7PR08MB3842.namprd08.prod.outlook.com" type="cite"> <div class="WordSection1"> Thanks again. <o:p> </o:p> Best regards, <o:p> </o:p> Jaromir <o:p> </o:p> </div> </blockquote> Thank you! Cheers, <pre class="moz-signature" cols="72">-- Juan Vuletich <a class="moz-txt-link-abbreviated" href="http://www.cuis-smalltalk.org">www.cuis-smalltalk.org</a> <a class="moz-txt-link-freetext" href="https://github.com/Cuis-Smalltalk/Cuis-Smalltalk-Dev">https://github.com/Cuis-Smalltalk/Cuis-Smalltalk-Dev</a> <a class="moz-txt-link-freetext" href="https://github.com/jvuletich">https://github.com/jvuletich</a> <a class="moz-txt-link-freetext" href="https://www.linkedin.com/in/juan-vuletich-75611b3">https://www.linkedin.com/in/juan-vuletich-75611b3</a> @JuanVuletich</pre> </body> </html>