Internal Server Error on reload of dfeed.js

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1. open 
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2. press reload (F5 or ctrl+R)

Re: trick to make throwing method @nogc

[Guest via Digitalmars-d-learn]

On Saturday, 25 February 2017 at 19:59:29 UTC, ikod wrote:

Hello,

I have a method for range:

struct Range {
immutable(ubyte[]) _buffer;
size_t _pos;

@property void popFront() pure @safe {
enforce(_pos < _buffer.length, "popFront from empty 
buffer");

_pos++;
}
}

I'd like to have @nogc here, but I can't because enforce() is 
non-@nogc.
I have a trick but not sure if it is valid, especially I don't 
know if optimization will preserve code, used for throwing:


import std.string;

struct Range {
immutable(ubyte[]) _buffer;
size_t  _pos;

this(immutable(ubyte[]) s) {
_buffer = s;
}
@property void popFront() pure @safe @nogc {
if (_pos >= _buffer.length ) {
auto _ = _buffer[$]; // throws RangeError
}
_pos++;
}
}

void main() {
auto r = Range("1".representation);
r.popFront();
r.popFront(); // throws
}

Is it ok to use it? Is there any better solution?

Thanks!


solution 1/
===

You can throw a static Exception.

auto staticEx(string msg, string file = __FILE__, size_t line = 
__LINE__)() @nogc

{
immutable static Exception e = new Exception(msg, file, line);
return e;
}

void main() @nogc
{
throw staticEx!"bla";
}

not good for the call stack display, tho.

solution 2/
===

Throw an Error. Errors shouldn't be caugth and consequently they 
lead to program termination so you don't care about the leak.



import std.experimental.allocator: make;
import std.experimental.allocator.mallocator: Mallocator;

void main() @nogc
{
throw make!Error(Mallocator.instance, "bla");
}

good when errors are not designed to be caught. not good for 
exceptions because might leak to death depending on how the 
exceptions happens (i.e in a loop ouch).


solution 3/
===

Reference counting. Not explored so far.

To finish, using a assert(0) is bad. assert(0) throws an error, 
it's really not like an Exception.