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digitalmars.D - Way to override/overload =?UTF-8?B?ROKAmXM=?= runtime assertions to

reply Alexander Nicholi <alex arqadium.com> writes:
Hello,

A project I’m helping develop mixes D code along with C and C++, 
and in the latter two languages we have custom macros that print 
things the way we need to, along with app-specific cleanup tasks 
before halting the program. Because it uses multiple languages, 
two of which have spotty or nonexistent exception support, and 
because we only depend on the D runtime sans libphobos, we have 
opted to avoid the use of exceptions in our codebase. Assertions 
still give us the ability to do contract programming to some 
extent, while C++ and D provide static assertions at compile-time 
to supplement.

With runtime assertions, C and C++ handle things amicably, but 
D’s `assert` builtin seems to fall back to C99’s assert.h 
handlers and there doesn’t seem to be a way around this. Is there 
a way to change this to use our own handlers with the D runtime? 
How does this change without the runtime, e.g. via `-betterC` 
code? If not, is this something that can be implemented in the 
language as a feature request? Our use case is a bit odd but 
still a possibility when using D as a systems-level language like 
this.

Thanks,
Alex
Jul 25 2018
next sibling parent Jonathan Marler <johnnymarler gmail.com> writes:
On Wednesday, 25 July 2018 at 15:24:50 UTC, Alexander Nicholi 
wrote:
 Hello,

 A project I’m helping develop mixes D code along with C and 
 C++, and in the latter two languages we have custom macros that 
 print things the way we need to, along with app-specific 
 cleanup tasks before halting the program. Because it uses 
 multiple languages, two of which have spotty or nonexistent 
 exception support, and because we only depend on the D runtime 
 sans libphobos, we have opted to avoid the use of exceptions in 
 our codebase. Assertions still give us the ability to do 
 contract programming to some extent, while C++ and D provide 
 static assertions at compile-time to supplement.

 With runtime assertions, C and C++ handle things amicably, but 
 D’s `assert` builtin seems to fall back to C99’s assert.h 
 handlers and there doesn’t seem to be a way around this. Is 
 there a way to change this to use our own handlers with the D 
 runtime? How does this change without the runtime, e.g. via 
 `-betterC` code? If not, is this something that can be 
 implemented in the language as a feature request? Our use case 
 is a bit odd but still a possibility when using D as a 
 systems-level language like this.

 Thanks,
 Alex
As far as I know, D's "assert" falls back to __assert. I have a pet/educational project (github.com/marler8997/maros) where I don't use the D runtime or the C runtime and my definition looks like this: extern (C) void __assert(bool cond, const(char)[] msg) { // TODO: would be nice to get a stack trace if (!cond) { version (linux) { import stdm.linux.file : stderr, write; import stdm.linux.process : exit; } else static assert(0, __FUNCTION__ ~ " not implemented on this platform"); write(stderr, "assert failed: "); write(stderr, msg); write(stderr, "\n"); exit(1); } } I just put this in my "object.d".
Jul 25 2018
prev sibling parent Mike Franklin <slavo5150 yahoo.com> writes:
On Wednesday, 25 July 2018 at 15:24:50 UTC, Alexander Nicholi 
wrote:
 Is there a way to change this to use our own handlers with the 
 D runtime?
You can provide your own implementations of the runtime hooks at https://github.com/dlang/druntime/blob/cb5efa9854775c5a72acd6870083b16e5ebba369/src/core/exception.d#L628 extern(C) void _d_assertp(immutable(char)* file, uint line) { import core.stdc.stdio; printf("Houston, we have a problem at %s:%u\n", file, line); } void main() { assert(false); } Try it out at https://run.dlang.io/is/QZEO9W
 How does this change without the runtime, e.g. via `-betterC` 
 code?
Unfortunately, this doesn't work with -betterC because -betterC seems to forward runtime assertions to the C implementation. See https://run.dlang.io/is/QZEO9W For that you have to provide a new implementation of `__assert`: extern(C) void __assert(const char *msg, const char *file, int line) { import core.stdc.stdio; printf("Houston, we have a problem at %s:%u\n", file, line); } extern(C) void main() { assert(false); } https://run.dlang.io/is/D5JxCT Mike
Jul 25 2018