Re: C++/D class interop example crashes
On Saturday, 27 March 2021 at 21:50:19 UTC, Jan wrote: On Saturday, 27 March 2021 at 18:39:53 UTC, Bastiaan Veelo wrote: The example links objects statically. You may be experiencing additional challenges with crossing DLL boundaries. I have not yet used DLLs, but did you initialise the D runtime? I haven't done anything extra (I'm pretty new to D). Do you mean calling this from the D code before using writeln? https://dlang.org/phobos/core_runtime.html#initialize I would have thought that happens automatically anyway. It should be in this case since the D code in the example is an application with a D main. The compiler will generate an extern(C) main that initializes the runtime and calls your D main. You have to initialize the runtime manually in three cases: you implement an extern(C) main yourself, you use WinMain instead of main, or you implement a shared library in D. The problem most likely has to do with your use of a DLL rather than linking statically as in the example. D interfaces with C DLLs just fine, but given that C++ compatibility is limited, I would expect issues when interfacing with C++ DLLs.
Re: code.dlang.org package search subtly broken?
On Saturday, 27 March 2021 at 20:36:08 UTC, bachmeier wrote: On Saturday, 27 March 2021 at 14:53:52 UTC, Imperatorn wrote: Yeah, the search is broken sadly. I made a PR about it some time ago. Partial searches doesn't work I don't think it's Dub search that's broken, really, it's that Dub uses MongoDB for searches, as discussed here: https://forum.dlang.org/post/mpeevfwstiymjzasb...@forum.dlang.org There have been complaints about Dub search for as long as I can remember, but for whatever reason it's never been brought up to standards. I have a fix for it but got stuck at setting up dub-registry. There was some config or credentiall issue or smth. Maybe I can try again next week
Re: Immutable
On Saturday, 27 March 2021 at 20:44:12 UTC, Brad wrote: I was looking through lots of sample code on Rosetta Code. D has a lot of solutions out there. That is really nice but it has me wondering - coming from other languages that do not support the concept of immutability - do real world programmers and/or hobbyists really use it as much as I see it on Rosetta Code? I know it adds a layer of security to your code, but I am still thinking "why?". Thanks for entertaining a newbie question. FYI, most of those examples were written by someone who goes by "Bearophile", and their style of writing D uses immutable/const/pure/nothrow/etc. wherever possible. It's not necessarily the style that all D programmers use, though there are a number of people that do. As for advantages, when it comes to the basic value types (int, float, bool, etc.), it's not all that useful. Where immutable can become very useful, though, is with types that have indirections (i.e. pointers). D's `string` type, for example, is actually a simple alias in Druntime: alias string = immutable(char)[]; Meaning "a mutable array of immutable chars". This means that you can modify the array itself, such as changing its length, appending to it, etc., but you cannot its individual elements. E.g., the following will work: string s1 = "this is a string"; s1 ~= '.'; assert(s1 == "this is a string."); But this will NOT work: string s2 = "this is a string "; s2[$ - 1] = '.'; Error: cannot modify immutable expression s2[__dollar - 1LU] This is just a simple example, but it allows the compiler to do some major optimizations on string handling code. Something that is usually very slow in C/C++ is such code, because strings are mutable arrays of mutable characters. Thus, they have to be copied around everywhere, which is slow and uses a lot of memory unnecessarily. Not so in D; because strings are mutable arrays of immutable characters, you can freely pass out references to the whole string, or a subrange of it. This would be very dangerous in C/C++, but in D you don't have to worry about the string changing out from under you by some code somewhere else in the program that you gave a reference to. Thus, string handling code is far faster in D than in C/C++. That is just one example, but you can see how immutable makes possible a lot of optimizations that would simply be impossible in languages without it.
Re: Immutable
On Saturday, 27 March 2021 at 20:44:12 UTC, Brad wrote: I was looking through lots of sample code on Rosetta Code. D has a lot of solutions out there. That is really nice but it has me wondering - coming from other languages that do not support the concept of immutability - do real world programmers and/or hobbyists really use it as much as I see it on Rosetta Code? I know it adds a layer of security to your code, but I am still thinking "why?". Thanks for entertaining a newbie question. I'm not enough of an expert on immutable to give an informed opinion (I don't care for the implementation). Jonathan Davis has written this blog post about the limitations of const, which also talks about immutable quite a bit: http://www.jmdavisprog.com/articles/why-const-sucks.html
Re: C++/D class interop example crashes
On Saturday, 27 March 2021 at 18:39:53 UTC, Bastiaan Veelo wrote: The example links objects statically. You may be experiencing additional challenges with crossing DLL boundaries. I have not yet used DLLs, but did you initialise the D runtime? I haven't done anything extra (I'm pretty new to D). Do you mean calling this from the D code before using writeln? https://dlang.org/phobos/core_runtime.html#initialize I would have thought that happens automatically anyway.
Immutable
I was looking through lots of sample code on Rosetta Code. D has a lot of solutions out there. That is really nice but it has me wondering - coming from other languages that do not support the concept of immutability - do real world programmers and/or hobbyists really use it as much as I see it on Rosetta Code? I know it adds a layer of security to your code, but I am still thinking "why?". Thanks for entertaining a newbie question.
Re: code.dlang.org package search subtly broken?
On Saturday, 27 March 2021 at 14:53:52 UTC, Imperatorn wrote: Yeah, the search is broken sadly. I made a PR about it some time ago. Partial searches doesn't work I don't think it's Dub search that's broken, really, it's that Dub uses MongoDB for searches, as discussed here: https://forum.dlang.org/post/mpeevfwstiymjzasb...@forum.dlang.org There have been complaints about Dub search for as long as I can remember, but for whatever reason it's never been brought up to standards.
Re: C++/D class interop example crashes
On Saturday, 27 March 2021 at 18:39:53 UTC, Bastiaan Veelo wrote: The example links objects statically. You may be experiencing additional challenges with crossing DLL boundaries. I have not yet used DLLs, but did you initialise the D runtime? — Bastiaan. This is an example taken from the documentation. It should work out of the box. I tried with LDC (don't have dmd on this computer) and I got this error: /usr/bin/ld: base.o: undefined reference to symbol '_d_allocclass' /usr/bin/ld: /usr/lib64/libdruntime-ldc-shared.so.90: error adding symbols: DSO missing from command line collect2: error: ld returned 1 exit status Given that someone interoperating with C++ probably cares about performance, it should also work out of the box with LDC, or at least tell you the changes that need to be made. I'll open an issue in the bug tracker when I return home (traveling now) if someone else doesn't.
Re: C++/D class interop example crashes
On Saturday, 27 March 2021 at 15:09:20 UTC, Jan wrote: I just tried to get this example to work: https://dlang.org/spec/cpp_interface.html#using_d_classes_from_cpp It kept crashing for me with a 'privileged instruction' error when the function 'bar' was executed. Finally I removed the call to writefln and voilà it finally works. So why does it fail? I assumed the standard library functions should all work. I'm compiling with "dmd -shared -m64 -debug" and link against a C++ DLL that was built with VS2019. Should the D DLL not contain everything to be self-sufficient to use it's entire runtime functionality? And if not, what other functions might be problematic? The example links objects statically. You may be experiencing additional challenges with crossing DLL boundaries. I have not yet used DLLs, but did you initialise the D runtime? — Bastiaan.
Re: code.dlang.org package search subtly broken?
On Saturday, 27 March 2021 at 14:53:52 UTC, Imperatorn wrote: Yeah, the search is broken sadly. I made a PR about it some time ago. Partial searches doesn't work Good to know. Thank you.
C++/D class interop example crashes
I just tried to get this example to work: https://dlang.org/spec/cpp_interface.html#using_d_classes_from_cpp It kept crashing for me with a 'privileged instruction' error when the function 'bar' was executed. Finally I removed the call to writefln and voilà it finally works. So why does it fail? I assumed the standard library functions should all work. I'm compiling with "dmd -shared -m64 -debug" and link against a C++ DLL that was built with VS2019. Should the D DLL not contain everything to be self-sufficient to use it's entire runtime functionality? And if not, what other functions might be problematic? Also, if anyone here has contacts to the people that maintain the samples, maybe someone should adjust the sample to not contain code that may break this way.
Re: code.dlang.org package search subtly broken?
On Saturday, 27 March 2021 at 13:48:10 UTC, Brian wrote: Hello -- When I go to https://code.dlang.org and use the search function on the top right corner, it usually works fine. However, there was one package I knew I specifically wanted (png-d) but when I typed png-d into the search bar, I was greeted with an error page, reproduced at the bottom of this message. I get this error whenever a hyphen is in the search query. I have not tested other special characters for this error. [...] Yeah, the search is broken sadly. I made a PR about it some time ago. Partial searches doesn't work
code.dlang.org package search subtly broken?
Hello -- When I go to https://code.dlang.org and use the search function on the top right corner, it usually works fine. However, there was one package I knew I specifically wanted (png-d) but when I typed png-d into the search bar, I was greeted with an error page, reproduced at the bottom of this message. I get this error whenever a hyphen is in the search query. I have not tested other special characters for this error. Thanks! ~Brian 500 - Internal Server Error Internal Server Error Internal error information: vibe.db.mongo.connection.MongoDriverException@../../vibe.d/mongodb/vibe/db/mongo/cursor.d(304): Query failed. Does the database exist? ??:? [0x562f5f97e175] ??:? [0x562f5f9a62b6] ??:? [0x562f5f98912d] /root/ldc2-1.24.0-linux-x86_64/bin/../import/std/exception.d:517 [0x562f5f3ee1c5] /root/ldc2-1.24.0-linux-x86_64/bin/../import/std/exception.d:437 [0x562f5f3e0625] /mnt/c/Users/soenke/develop/0-dlang/dub-registry/../../vibe.d/mongodb/vibe/db/mongo/cursor.d:304 [0x562f5f44820d] /mnt/c/Users/soenke/develop/0-dlang/dub-registry/source/app.d:462 [0x562f5f448cb0] /mnt/c/Users/soenke/develop/0-dlang/dub-registry/source/app.d:322 [0x562f5f448ad7] /mnt/c/Users/soenke/develop/0-dlang/dub-registry/source/app.d:367 [0x562f5f470f96] /mnt/c/Users/soenke/develop/0-dlang/dub-registry/../../vibe.d/mongodb/vibe/db/mongo/cursor.d:233 [0x562f5f447cfd] /mnt/c/Users/soenke/develop/0-dlang/dub-registry/../../vibe.d/mongodb/vibe/db/mongo/cursor.d:60 [0x562f5f36ba6d] /root/ldc2-1.24.0-linux-x86_64/bin/../import/std/algorithm/iteration.d:615 [0x562f5f470088] /root/ldc2-1.24.0-linux-x86_64/bin/../import/std/array.d:140 [0x562f5f366182] /mnt/c/Users/soenke/develop/0-dlang/dub-registry/source/dubregistry/dbcontroller.d:333 [0x562f5f31dee0] /mnt/c/Users/soenke/develop/0-dlang/dub-registry/source/dubregistry/registry.d:103 [0x562f5f2eba03] /mnt/c/Users/soenke/develop/0-dlang/dub-registry/source/dubregistry/web.d:476 [0x562f5f2eb967] /mnt/c/Users/soenke/develop/0-dlang/dub-registry/../../vibe.d/web/vibe/web/web.d:1043 [0x562f5f39947a] /mnt/c/Users/soenke/develop/0-dlang/dub-registry/../../vibe.d/web/vibe/web/web.d:214 [0x562f5f399083] router.d:218 [0x562f5f7f0024] router.d:674 [0x562f5f7f2856] router.d:607 [0x562f5f7efcf6] router.d:211 [0x562f5f7efaae] server.d:2292 [0x562f5f7f80cb] server.d:253 [0x562f5f7f64fe] server.d:245 [0x562f5f7f5dbd] server.d:2048 [0x562f5f80047e] task.d:712 [0x562f5f8ea4b5] task.d:730 [0x562f5f8e7091] task.d:439 [0x562f5f8e67db] ??:? [0x562f5f97f5ba]
Re: isPOD is broken?
On Friday, 26 March 2021 at 12:13:29 UTC, kinke wrote: A class *reference* is always a POD. Only structs can be non-PODs. In this case what means "does not have virtual functions, does not inherit"? Structs doesn't have virtual methods and they can't inherits.
