Re: Why is (int[int] s = int[int].init) not allowed

2020-12-23 Thread Andre Pany via Digitalmars-d-learn 
On Wednesday, 23 December 2020 at 07:08:31 UTC, Daniel Kozak 
wrote:
Dne st 23. 12. 2020 1:00 uživatel Steven Schveighoffer via 
Digitalmars-d-learn  napsal:



On 12/22/20 5:44 PM, Daniel Kozak wrote:
> [...]

Yeah:

void sample_valid(int[int] s = null)

-Steve



Yes AA.init is null per doc.

https://dlang.org/spec/hash-map.html#construction_and_ref_semantic


Thanks for clarification, I was not aware that AA.init is 
technically the same as null.


Kind regards
Andre

Re: Why is (int[int] s = int[int].init) not allowed

2020-12-22 Thread Daniel Kozak via Digitalmars-d-learn 
Dne st 23. 12. 2020 1:00 uživatel Steven Schveighoffer via
Digitalmars-d-learn  napsal:

> On 12/22/20 5:44 PM, Daniel Kozak wrote:
> > On Tue, Dec 22, 2020 at 10:15 PM Andre Pany via Digitalmars-d-learn
> >  > > wrote:
> >
> > Hi,
> >
> > I am really confused, why is this valid:
> > void sample(string[string] s = string[string].init){}
> >
> > while this causes syntax errors?
> >
> > void sample_invalid1(double[string] s = double[string].init){}
> > void sample_invalid2(int[int] s = int[int].init){}
> >
> > Kind regards
> > André
> >
> >
> > As has been said this is an oddity in the grammar. But why would anyone
> > need to use this anyway?
> >
> >void sample_invalid2(int[int] s = int[int].init){}
> >
> > seems really awful to me anyway.
>
> Yeah:
>
> void sample_valid(int[int] s = null)
>
> -Steve


Yes AA.init is null per doc.

https://dlang.org/spec/hash-map.html#construction_and_ref_semantic

Re: Why is (int[int] s = int[int].init) not allowed

2020-12-22 Thread Steven Schveighoffer via Digitalmars-d-learn 

On 12/22/20 5:44 PM, Daniel Kozak wrote:
On Tue, Dec 22, 2020 at 10:15 PM Andre Pany via Digitalmars-d-learn 
> wrote:


Hi,

I am really confused, why is this valid:
void sample(string[string] s = string[string].init){}

while this causes syntax errors?

void sample_invalid1(double[string] s = double[string].init){}
void sample_invalid2(int[int] s = int[int].init){}

Kind regards
André


As has been said this is an oddity in the grammar. But why would anyone 
need to use this anyway?


   void sample_invalid2(int[int] s = int[int].init){}

seems really awful to me anyway.


Yeah:

void sample_valid(int[int] s = null)

-Steve

Re: Why is (int[int] s = int[int].init) not allowed

2020-12-22 Thread Daniel Kozak via Digitalmars-d-learn 
On Tue, Dec 22, 2020 at 10:15 PM Andre Pany via Digitalmars-d-learn <
digitalmars-d-learn@puremagic.com> wrote:

> Hi,
>
> I am really confused, why is this valid:
> void sample(string[string] s = string[string].init){}
>
> while this causes syntax errors?
>
> void sample_invalid1(double[string] s = double[string].init){}
> void sample_invalid2(int[int] s = int[int].init){}
>
> Kind regards
> André
>

As has been said this is an oddity in the grammar. But why would anyone
need to use this anyway?

  void sample_invalid2(int[int] s = int[int].init){}

seems really awful to me anyway.

Re: Why is (int[int] s = int[int].init) not allowed

2020-12-22 Thread Andre Pany via Digitalmars-d-learn 

On Tuesday, 22 December 2020 at 22:02:54 UTC, ag0aep6g wrote:

On Tuesday, 22 December 2020 at 21:11:12 UTC, Andre Pany wrote:

[...]


Looks like an oddity in the grammar.

`string` is an alias, meaning it's an identifier. And an 
identifier is a valid expression to the grammar. So 
`string[string]` is parsed as an IndexExpression. Only during 
semantic analysis does the compiler figure out that it's 
actually a type.


`double` and `int` aren't identifiers. They're keywords. And 
they're always types, never expressions. So `int[int]` cannot 
be parsed as an IndexExpression. It's parsed as a Type instead. 
And for a (grammatical) Type, there is no rule that allows 
`Type.Identifier`.


You can work around with parentheses:

(double[string]).init;
(int[int]).init


Thanks a lot!

Kind regards
Andre

Re: Why is (int[int] s = int[int].init) not allowed

2020-12-22 Thread ag0aep6g via Digitalmars-d-learn 

On Tuesday, 22 December 2020 at 21:11:12 UTC, Andre Pany wrote:

I am really confused, why is this valid:
void sample(string[string] s = string[string].init){}

while this causes syntax errors?

void sample_invalid1(double[string] s = double[string].init){}
void sample_invalid2(int[int] s = int[int].init){}


Looks like an oddity in the grammar.

`string` is an alias, meaning it's an identifier. And an 
identifier is a valid expression to the grammar. So 
`string[string]` is parsed as an IndexExpression. Only during 
semantic analysis does the compiler figure out that it's actually 
a type.


`double` and `int` aren't identifiers. They're keywords. And 
they're always types, never expressions. So `int[int]` cannot be 
parsed as an IndexExpression. It's parsed as a Type instead. And 
for a (grammatical) Type, there is no rule that allows 
`Type.Identifier`.


You can work around with parentheses:

(double[string]).init;
(int[int]).init

Why is (int[int] s = int[int].init) not allowed

2020-12-22 Thread Andre Pany via Digitalmars-d-learn 

Hi,

I am really confused, why is this valid:
void sample(string[string] s = string[string].init){}

while this causes syntax errors?

void sample_invalid1(double[string] s = double[string].init){}
void sample_invalid2(int[int] s = int[int].init){}

Kind regards
André