[Pas2js] My 1st type helper

[Mattias Gaertner]

On Wed, 27 Feb 2019 06:07:35 -0700 (MST)
warleyalex via Pas2js <pas2js at lists.freepascal.org> wrote:

> -------------------------------------------
> type
>  TFloatHelper  =  type helper for Float  
>    const NPI = 3.141592;
>    function ToStr: String;
>  end;
> 
> function  TFloatHelper.ToStr: String;
> begin
>   Result:=  FloatToStr(Self);
> end;
> 
> ------------------------
> this syntax
> //  TFloatHelper  =  helper for Float 
> 
> // hum, doesn't work for me, I had to include the keyword type

Correct.
In $mode delphi you can use 'record helper for Float'.

> How to use the float helper function ToStr?
> 
> -----------------------
> var
>   ReturnValue : Float;
> begin
>   ReturnValue := 2.71;
>     console.log(ReturnValue * ReturnValue.NPI);                     
> //8.51371432
> //  console.log((ReturnValue * ReturnValue.NPI).ToStr);

FPC and Delphi do not allow that. I don't know why. pas2js does.


> //8.51371432  does not work for me
> //  console.log((ReturnValue * TFloatHelper.NPI).ToStr);         

Helpers are not full types. They extend types:

(ReturnValue * Float.NPI).ToStr

> //8.51371432 does not work for me
> //  console.log(TFloatHelper.ToStr(ReturnValue *
> Float.NPI));  //8.51371432 does not work for me

Good.

> //  console.log((ReturnValue *
> ReturnValue.NPI).ToStr );        //8.51371432 does not work for me

Isn't that same as above?

Mattias

> 
> 
> 
> 
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