Pike-devel August 2019

pike-devel@lists.lysator.liu.se

7 participants
15 discussions

Use of ::_destruct() in arbitrary objects
by Chris Angelico 26 Aug '19

26 Aug '19

In digging into a problem with Protocols.HTTP.Promise, I came across an issue with inheritance and destructors. #ifdef HTTP_PROMISE_DESTRUCT_DEBUG # define PROMISE_DESTRUCTOR \ protected void _destruct() { \ werror("%O()._destruct()\n", object_program(this)); \ } #else # define PROMISE_DESTRUCTOR #endif Activating this debug flag actually prevents the parent destructors from being called. And simply adding ::_destruct() into there doesn't work either, as that will break for anything that DOESN'T have a _destruct in its parent. How can this be solved generically? The symbol ::_destruct simply can't be looked up (at compile time) if the parent doesn't have one. ChrisA

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Comments/thoughts requested: Generators and async functions in Pike
by Chris Angelico 26 Aug '19

26 Aug '19

Pike now (8.1) has a decent promise/future subsystem. It's always had great handling of multiple asynchronous operations (GUI, socket, time delay, etc) with the convenience of just returning -1 from main. Interested in people's opinions on whether it would be of value to introduce generators and (built on them) asynchronous functions. I'm borrowing terminology heavily from Python and ECMAScript here, and both of them have drawn from prior art. A *generator function* is a function that can be partially run, then set aside until resumed. Effectively, its stack frame can be encapsulated in an object for future use. It would look something like this: int get_numbers() { write("Starting\n"); yield 1; write("Continuing\n"); yield 2; write("Finishing\n"); return 3; } Calling get_numbers would prepare an execution context, but not actually begin running the function at all. The caller would get back a *generator object*. Asking this generator object to produce its next value would begin executing the function, triggering the call to write, and would stop at the first yield point, returning that value (1). Asking for another value resumes the function, triggering the second write, and returns the next yielded value. The third time you request a value, it would run the function to completion, and report that it returned (not yielded) 3. (The types yielded don't have to match the type of the return value. I'm not sure if there's a good way to declare the yielded types, or if it's best to just assume 'mixed'.) A generator object would be an Iterator, allowing you to loop over the yielded values easily: foreach (get_numbers() ;; int num) The 'yield' keyword would be an expression/operator, allowing you to send a value back into the generator function as the result of the yield expression. The awesomeness of this becomes more apparent when combined with Concurrent.Future objects. An asynchronous function would be a generator which yields Futures until it is ready to return a value. Calling such a function automatically returns a ready-to-go Future, set up such that it is automatically transform_with'd the next yielded Future, or transform'd into the returned value. It would be used somewhat thus: void show_channel_info(string name) { int id = yield get_channel_id(name); mapping data = yield query_channel(id); write("Status: %s\n", data->status); mapping stream = yield get_stream_info(id); if (stream) write("%s is online, %s\n", name, stream->uptime); else write("%s is offline.\n", name); } This is WAY more readable than the equivalent with a bunch of lambda functions to capture the intermediate values. Thoughts? Concerns? Questions? ChrisA

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Re: SSL cert for pike.lysator.liu.se has expired
by Chris Angelico 23 Aug '19

23 Aug '19

On Fri, Aug 23, 2019 at 11:59 PM Peter Bortas @ Pike developers forum <10353(a)lyskom.lysator.liu.se> wrote: > > I guess that's me. Fixed. Thanks! I was doing some Pike coding on live-stream today and one of my viewers mentioned it. Appreciate the quick fix! ChisA

1 0

SSL cert for pike.lysator.liu.se has expired
by Chris Angelico 23 Aug '19

23 Aug '19

Going to https://pike.lysator.liu.se/ shows a big warning about the certificate having expired. Who's in charge of this? ChrisA

2 1

Broken online documentation
by Tomasz Jamroszczak 02 Aug '19

02 Aug '19

When I look for for "Timer" in the "Site search" box on http://pike.lysator.liu.se/generated/manual/modref/ex/predef_3A_3A/System.h… page, I can see link to System.Timer http://pike.lysator.liu.se/generated/manual/modref/ex/predef_3A_3A/System/T… but it returns HTTP 404. Best Regards, Tomasz Jamroszczak

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Pike-devel August 2019