Re: Non-Initialized Dynamic Arrays Construction

2014-02-24 Thread TheFlyingFiddle

On Monday, 24 February 2014 at 13:08:52 UTC, Mengu wrote:

On Monday, 24 February 2014 at 11:29:39 UTC, bearophile wrote:

TheFlyingFiddle:

http://dlang.org/phobos/std_array.html#.uninitializedArray is 
what you want.


The OP wants minimallyInitializedArray. uninitializedArray is 
only for special situations. Perhaps we have to fix the online 
docs to underline this.


Bye,
bearophile


what's the difference?


Well for anything that does not have indirections eg numbers / 
chars and structs without classes/arrays/pointers in them. Then 
the two functions are equivalent.


So:

int[] first  = uninitializedArray!(int[])(n);
int[] second = minimallyInitializedArray!(int[])(n);

Both first and second contain garbaged values.

int*[] third = uninitializedArray!(int*[])(n);
int*[] forth = minimallyInitializedArray!(int*[])(n);

The third array contains garbage but all elements in forth are 
initialized to null.


I assume this behavior is this way since an int with a garbage 
value is not as bad as a garbage pointer dereference into memory.


The OP wants minimallyInitializedArray. uninitializedArray is 
only for special situations.


True but uninitializedArray corresponds to = void semantics for 
all arrays.
minimallyInitializedArray is safer though so i guess it should be 
used.


Wouldn't it be nice to have some kind of syntactic sugar for 
this similar to what we have for static arrays?


BTW: Why isn't simply the following allowed?

 int n = 3;
 int[n] = void;

Is it too easy to confuse with static array syntax?


I don't like this, since it would be wierd from an allocation 
view point. How is int[n] allocated? Is it the GC? Is it alloca? 
Can i overide the allocation mechanism? Does the allocated array 
behave the same as a static array? (it gets destroyed if it goes 
out of scope)


I think it gets a little confusing and also personally i don't 
want more hidden memory allocations. We already have alot of 
those.


Re: Non-Initialized Dynamic Arrays Construction

2014-02-24 Thread bearophile

Mengu:


what's the difference?


After you have read the online docs of both function what's your 
best guess of an answer?


Bye,
bearophile


Re: Non-Initialized Dynamic Arrays Construction

2014-02-24 Thread Mengu

On Monday, 24 February 2014 at 11:29:39 UTC, bearophile wrote:

TheFlyingFiddle:

http://dlang.org/phobos/std_array.html#.uninitializedArray is 
what you want.


The OP wants minimallyInitializedArray. uninitializedArray is 
only for special situations. Perhaps we have to fix the online 
docs to underline this.


Bye,
bearophile


what's the difference?


Re: Non-Initialized Dynamic Arrays Construction

2014-02-24 Thread Andrej Mitrovic
On 2/24/14, bearophile  wrote:
> The OP wants minimallyInitializedArray. uninitializedArray is
> only for special situations.

There needs to be a ddoc-ed sample demonstrating *exactly* what the
difference between minimallyInitializedArray and uninitializedArray
is.


Re: Non-Initialized Dynamic Arrays Construction

2014-02-24 Thread Francesco Cattoglio

On Monday, 24 February 2014 at 12:08:31 UTC, Nordlöw wrote:

On Monday, 24 February 2014 at 11:29:39 UTC, bearophile wrote:

TheFlyingFiddle:

http://dlang.org/phobos/std_array.html#.uninitializedArray is 
what you want.


Wouldn't it be nice to have some kind of syntactic sugar for 
this similar to what we have for static arrays?


BTW: Why isn't simply the following allowed?

int n = 3;
int[n] = void;

Is it too easy to confuse with static array syntax?


to me, it also looks like you are creating an array of ints, and 
trying to void it's reference. I honestly don't like the look of 
it either.
Something like "auto arr = new float[n].void" would fit better, 
but still looks horrible IMO :)


Re: Non-Initialized Dynamic Arrays Construction

2014-02-24 Thread simendsjo

On 02/24/2014 01:08 PM, "Nordlöw" wrote:

On Monday, 24 February 2014 at 11:29:39 UTC, bearophile wrote:

TheFlyingFiddle:


http://dlang.org/phobos/std_array.html#.uninitializedArray is what
you want.


Wouldn't it be nice to have some kind of syntactic sugar for this
similar to what we have for static arrays?

BTW: Why isn't simply the following allowed?

 int n = 3;
 int[n] = void;

Is it too easy to confuse with static array syntax?


Seems very dangerous. If n is available at compile-time it's a static 
array, else it's dynamic..?


Re: Non-Initialized Dynamic Arrays Construction

2014-02-24 Thread Nordlöw

On Monday, 24 February 2014 at 11:29:39 UTC, bearophile wrote:

TheFlyingFiddle:

http://dlang.org/phobos/std_array.html#.uninitializedArray is 
what you want.


Wouldn't it be nice to have some kind of syntactic sugar for this 
similar to what we have for static arrays?


BTW: Why isn't simply the following allowed?

int n = 3;
int[n] = void;

Is it too easy to confuse with static array syntax?


Re: Non-Initialized Dynamic Arrays Construction

2014-02-24 Thread bearophile

TheFlyingFiddle:

http://dlang.org/phobos/std_array.html#.uninitializedArray is 
what you want.


The OP wants minimallyInitializedArray. uninitializedArray is 
only for special situations. Perhaps we have to fix the online 
docs to underline this.


Bye,
bearophile


Re: Non-Initialized Dynamic Arrays Construction

2014-02-24 Thread TheFlyingFiddle

On Monday, 24 February 2014 at 11:11:44 UTC, Nordlöw wrote:

Is it possible void construct a dynamic array such as b in

int n = 3;
auto b = new float[n];

similar to what we do with static arrays as in

int[3] c = void;


http://dlang.org/phobos/std_array.html#.uninitializedArray is 
what you want.


Non-Initialized Dynamic Arrays Construction

2014-02-24 Thread Nordlöw

Is it possible void construct a dynamic array such as b in

int n = 3;
auto b = new float[n];

similar to what we do with static arrays as in

int[3] c = void;