digitalmars.D.bugs - [Issue 9265] New: Nullable fixed-sized array wrapper
- d-bugmail puremagic.com (79/79) Jan 03 2013 http://d.puremagic.com/issues/show_bug.cgi?id=9265
- d-bugmail puremagic.com (13/15) Feb 04 2013 http://d.puremagic.com/issues/show_bug.cgi?id=9265
- d-bugmail puremagic.com (13/13) Mar 02 2013 http://d.puremagic.com/issues/show_bug.cgi?id=9265
- d-bugmail puremagic.com (7/18) Mar 02 2013 http://d.puremagic.com/issues/show_bug.cgi?id=9265
- d-bugmail puremagic.com (11/25) Mar 02 2013 http://d.puremagic.com/issues/show_bug.cgi?id=9265
- d-bugmail puremagic.com (17/17) Mar 02 2013 http://d.puremagic.com/issues/show_bug.cgi?id=9265
http://d.puremagic.com/issues/show_bug.cgi?id=9265
Summary: Nullable fixed-sized array wrapper
Product: D
Version: D2
Platform: All
OS/Version: All
Status: NEW
Severity: enhancement
Priority: P2
Component: Phobos
AssignedTo: nobody puremagic.com
ReportedBy: bearophile_hugs eml.cc
When I use fixed-sized arrays a lot, sometimes I need a nullable version of
them (fixed-sized arrays are allocated in-place, so they often avoid heap
allocations, avoiding the creation of some garbage, reducing the GC pressure
and generally speeding up the code). A "ref" can't be used because it can't be
null.
So I think the normal way to use them in D is this, but the "(*arr)[1]" syntax
is bug-prone and not elegant:
alias TA = immutable(int[5]);
bool foo(TA* arr) {
if (arr)
return (*arr)[1] == 20;
else
return false;
}
void main() {
TA a;
foo(&a);
}
std.typecons.Nullable and std.typecons.NullableRef contain enforce() that
throws and kills inlining.
This simple struct inspired by NullableRef is light, avoids the problem of
NullableRef and allows for a natural syntax for nullable fixed sized arrays:
// Nullable fixed-sized array --------
struct Ptr(T) {
private T* ptr;
this(T* ptr_) pure nothrow {
this.ptr = ptr_;
}
bool opCast(T)() const pure nothrow if (is(T == bool)) {
return ptr !is null;
}
property ref inout(T) get()() inout pure nothrow
in {
assert(ptr);
} body {
return *ptr;
}
alias get this;
}
Ptr!T ptr(T)(ref T x) {
return typeof(return)(&x);
}
// Example usage ----------
alias TA = immutable(int[5]);
bool foo(Ptr!TA arr=Ptr!TA.init) nothrow {
if (arr)
return arr[1] == 20;
else
return false;
}
bool foo(typeof(null) _) nothrow {
return false;
}
void main() {
assert(!foo());
assert(!foo(null));
TA items = [10, 20, 30, 40, 50];
assert(foo(ptr(items)));
}
//---------------------------------
Unfortunately my benchmarks show that with the current DMD 2.061 the code that
uses such wrapped array is not as efficient as the first program that uses the
pointer to the fixed sized array.
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Jan 03 2013
d-bugmail puremagic.com
http://d.puremagic.com/issues/show_bug.cgi?id=9265
monarchdodra gmail.com changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |monarchdodra gmail.com
std.typecons.Nullable and std.typecons.NullableRef contain enforce() that
throws and kills inlining.
FYI: I submitted a pull that changes those enforces to logic errors (asserts):
https://github.com/D-Programming-Language/phobos/pull/1103
This should allow the code to inline.
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Feb 04 2013
http://d.puremagic.com/issues/show_bug.cgi?id=9265 Commits pushed to master at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/e2831a5f2a7f3a8b0df4e475ff4f79fea2ff5c0f Fixes Issue 9265 - assertNotThrown should emit msg from thrown exception if available. https://github.com/D-Programming-Language/phobos/commit/ba4095de5f2c6c62dbec45b71ec3e4ba3d802f90 Issue 9265 - assertNotThrown should emit msg from thrown exception if available. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Mar 02 2013
http://d.puremagic.com/issues/show_bug.cgi?id=9265Commits pushed to master at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/e2831a5f2a7f3a8b0df4e475ff4f79fea2ff5c0f Fixes Issue 9265 - assertNotThrown should emit msg from thrown exception if available. https://github.com/D-Programming-Language/phobos/commit/ba4095de5f2c6c62dbec45b71ec3e4ba3d802f90 Issue 9265 - assertNotThrown should emit msg from thrown exception if available.Is this related? -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Mar 02 2013
http://d.puremagic.com/issues/show_bug.cgi?id=9265
Andrej Mitrovic <andrej.mitrovich gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |andrej.mitrovich gmail.com
13:39:58 PST ---
Commits pushed to master at https://github.com/D-Programming-Language/phobos
https://github.com/D-Programming-Language/phobos/commit/e2831a5f2a7f3a8b0df4e475ff4f79fea2ff5c0f
Fixes Issue 9265 - assertNotThrown should emit msg from thrown exception if
available.
https://github.com/D-Programming-Language/phobos/commit/ba4095de5f2c6c62dbec45b71ec3e4ba3d802f90
Issue 9265 - assertNotThrown should emit msg from thrown exception if
available.
Is this related?
No it was a typo in the commit message, sorry.
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Mar 02 2013
http://d.puremagic.com/issues/show_bug.cgi?id=9265
bearophile_hugs eml.cc changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
Using the updated NullableRef in my code I've seen that it is good enough for
the purposes explained here, so I close down this issue.
I'd like a more handy way to create a nullable, like:
Ptr!T ptr(T)(ref T x) {
return typeof(return)(&x);
}
So I've created the Issue 9637
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Mar 02 2013