I have a function type and variable and assign a function to it:

void function( int i ) myFunc;
myFunc = void function( int i ) { myCode; }

How would I declare an alias for void function( int i ) such that the case above would work like this:

// alias MF = void function( int i );  // not working
// alias void function( int i ) MF;  // not working

MF myFunc;
myFunc = MF { myCode };

Please, if possible, also show me where I should have found the answer (D Reference, Alis book, etc. )

On Tuesday, 12 January 2016 at 15:41:02 UTC, ParticlePeter wrote:
> I have a function type and variable and assign a function to it:
>
> void function( int i ) myFunc;
> myFunc = void function( int i ) { myCode; }
>
> How would I declare an alias for void function( int i ) such that the case above would work like this:
>
> // alias MF = void function( int i );  // not working
> // alias void function( int i ) MF;  // not working
>
> MF myFunc;
> myFunc = MF { myCode };
>
> Please, if possible, also show me where I should have found the answer (D Reference, Alis book, etc. )

This works for me:

alias MF = void function(int i);  // works fine - what was your error?

void main() {
    import std.stdio;
    MF myFunc;
    // you can also use the full `function(int i) { ... }` in the next line
    myFunc = (i) { writeln("i = ", i); };
    myFunc(42);
}

V Tue, 12 Jan 2016 15:41:02 +0000
ParticlePeter via Digitalmars-d-learn
<digitalmars-d-learn@puremagic.com> napsáno:

> I have a function type and variable and assign a function to it:
> 
> void function( int i ) myFunc;
> myFunc = void function( int i ) { myCode; }
> 
> How would I declare an alias for void function( int i ) such that the case above would work like this:
> 
> // alias MF = void function( int i );  // not working
> // alias void function( int i ) MF;  // not working
> 
> MF myFunc;
> myFunc = MF { myCode };
> 
> Please, if possible, also show me where I should have found the answer (D Reference, Alis book, etc. )

alias void MF(int i);

On 12.01.2016 16:41, ParticlePeter wrote:
> // alias MF = void function( int i );  // not working
> // alias void function( int i ) MF;  // not working

These are both fine. The first one is the preferred style.

>
> MF myFunc;
> myFunc = MF { myCode };

This line doesn't work. Function literals don't take a type before the curly braces. They have their own syntax. See http://dlang.org/spec/expression.html (search for "Function Literals").

Since most of the stuff in function literals can be inferred from the context, something as simple as this works:
myFunc = (i) { myCode };

On Tuesday, 12 January 2016 at 15:57:03 UTC, Marc Schütz wrote:
> On Tuesday, 12 January 2016 at 15:41:02 UTC, ParticlePeter wrote:
>> I have a function type and variable and assign a function to it:
>>
>> void function( int i ) myFunc;
>> myFunc = void function( int i ) { myCode; }
>>
>> How would I declare an alias for void function( int i ) such that the case above would work like this:
>>
>> // alias MF = void function( int i );  // not working
>> // alias void function( int i ) MF;  // not working
>>
>> MF myFunc;
>> myFunc = MF { myCode };
>>
>> Please, if possible, also show me where I should have found the answer (D Reference, Alis book, etc. )
>
> This works for me:
>
> alias MF = void function(int i);  // works fine - what was your error?
>
> void main() {
>     import std.stdio;
>     MF myFunc;
>     // you can also use the full `function(int i) { ... }` in the next line
>     myFunc = (i) { writeln("i = ", i); };
>     myFunc(42);
> }

Not what I wanted, I wanted the parameter to be part of the alias:
myFunc = MF { ... }

I want to pass such a function to another function:

alias MF = void function(int i);
void otherFunc( void function( int ) mf );
otherFunc( MF { ... } );      // Getting Error: found '{' when expecting ','

Actually, I do use only one param, and not int as well, hence I would like the parameter list to be part of the alias.
Your example works though.

On 01/12/2016 07:41 AM, ParticlePeter wrote:

> Please, if possible, also show me where I should have found the answer
> (D Reference, Alis book

It is not used with a function literal but searching for 'alias' below yields something close: :)

  http://ddili.org/ders/d.en/lambda.html

<quote>
Function pointer syntax is relatively harder to read; it is common to make code more readable by an alias:

alias CalculationFunc = int function(char, double);

That alias makes the code easier to read:

    CalculationFunc ptr = &myFunction;

As with any type, auto can be used as well:

    auto ptr = &myFunction;
</quote>

As others have already said, &myFunction can be replaced with a lambda. Shamefully without compiling:

    auto ptr = (char, double) => 42;

Ali

On Tuesday, 12 January 2016 at 16:00:37 UTC, Daniel Kozak wrote:
> V Tue, 12 Jan 2016 15:41:02 +0000
> ParticlePeter via Digitalmars-d-learn
> <digitalmars-d-learn@puremagic.com> napsáno:
>
>> I have a function type and variable and assign a function to it:
>> 
>> void function( int i ) myFunc;
>> myFunc = void function( int i ) { myCode; }
>> 
>> How would I declare an alias for void function( int i ) such that the case above would work like this:
>> 
>> // alias MF = void function( int i );  // not working
>> // alias void function( int i ) MF;  // not working
>> 
>> MF myFunc;
>> myFunc = MF { myCode };
>> 
>> Please, if possible, also show me where I should have found the answer (D Reference, Alis book, etc. )
>
> alias void MF(int i);

That does not work:
alias void MF(int i);
MF mf;     // Error: variable mf cannot be declared to be a function

On 01/12/2016 08:22 AM, ParticlePeter wrote:
> On Tuesday, 12 January 2016 at 15:57:03 UTC, Marc Schütz wrote:

> Not what I wanted, I wanted the parameter to be part of the alias:
> myFunc = MF { ... }
>
> I want to pass such a function to another function:
>
> alias MF = void function(int i);
> void otherFunc( void function( int ) mf );
> otherFunc( MF { ... } );      // Getting Error: found '{' when expecting

I've added otherFunc(MF) to Marc Schütz's program:

alias MF = void function(int i);

void otherFunc(MF func) {
    func(42);
}

void main() {
    import std.stdio;
    MF myFunc;
    // you can also use the full `function(int i) { ... }` in the next line
    myFunc = (i) { writeln("i = ", i); };
    myFunc(42);

    otherFunc((i) { writefln("otherFunc called me with %s", i); });
}

Ali

On Tuesday, 12 January 2016 at 16:22:48 UTC, ParticlePeter wrote:

> Actually, I do use only one param, and not int as well, hence I would like the parameter list to be part of the alias.
> Your example works though.

This was confusing, lets start fresh:

I have a function "otherFunc" which takes a function with lots of parameters as argument:

void otherFunc( void function( ref int p1, float p2, ubyte p3, ... ) mf );

Side-note, I use the keyword function to signal that it is a function and not a delegate, thought it is a delegate when not specified.

When I pass a parameter to otherFunc I use this syntax for an anonymous function parameter:

otherFunc( void function( ref int p1, float p2, ubyte p3 ) { myCode; } );

I would like to alias the function signature above:
alias MF = void function( ref int p1, float p2, ubyte p3 );

I can rewrite the definition of otherFunc like this:
void otherFunc( MF mf );

But I cannot pass an anonymous function to otherFunc like this:
otherFunc( MF { myCode; } );

Thats what I want. Any working example?


Ali, I do not pass an existing named function as a pointer. I am also not sure about the lambdas, as I do not return anything, I just want to process data, would that work?

On 01/12/2016 08:55 AM, ParticlePeter wrote:

> I have a function "otherFunc" which takes a function with lots of
> parameters as argument:
>
> void otherFunc( void function( ref int p1, float p2, ubyte p3, ... ) mf );

Ok.

> otherFunc( void function( ref int p1, float p2, ubyte p3 ) { myCode; } );

Ok.

> alias MF = void function( ref int p1, float p2, ubyte p3 );

Ok.

> I can rewrite the definition of otherFunc like this:
> void otherFunc( MF mf );

That has the same problem of trying to do this for int:

void foo(int i) {
}

void main() {
    foo(int 42);     // <-- ERROR
}

But you can do this:

    foo(int(42));    // (Relatively new syntax in D.)

> But I cannot pass an anonymous function to otherFunc like this:
> otherFunc( MF { myCode; } );

It works with the parentheses as it does for int:

alias MF = void function( ref int p1, float p2, ubyte p3 );

void otherFunc( MF mf ) {
}

void main() {
    otherFunc(MF((ref int, float, ubyte){ }));    // <-- Parens
}

> not sure about the lambdas, as I do not return anything, I just want to
> process data, would that work?

Yes, some lambdas do not return anything.

Ali