Re: [fpc-pascal] Parameterless constructors are not allowed in records or record/type helpers

[Ryan Joseph]

Thanks got it now. Not ideal but it works and is a small improvement over a 
function.

> On Feb 6, 2017, at 2:06 PM, Sven Barth  wrote:
> 
> You need to add the "static" modifier to the method. Class functions in 
> records can't have a self parameter and the "static" disables that. That's 
> why.
> 
> 

Regards,
Ryan Joseph

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Re: [fpc-pascal] Parameterless constructors are not allowed in records or record/type helpers

[Sven Barth]

Am 06.02.2017 02:37 schrieb "Ryan Joseph" :
>
> I tried class functions in records already but I got the error "Class
methods must be static in records”. Not sure what that means but I assumed
they don’t work either.

You need to add the "static" modifier to the method. Class functions in
records can't have a self parameter and the "static" disables that. That's
why.

Regards,
Sven
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Re: [fpc-pascal] Parameterless constructors are not allowed in records or record/type helpers

[Ryan Joseph]

I tried class functions in records already but I got the error "Class methods 
must be static in records”. Not sure what that means but I assumed they don’t 
work either.

Too bad, that would be a nice feature.

> On Feb 6, 2017, at 2:29 AM, Sven Barth  wrote:
> 
> Oh, well, it was worth a shot... Alternatively you could declare a class 
> function named Create that returns an instance of the record. Even Delphi is 
> using that for Rtti.TRttiContext.

Regards,
Ryan Joseph

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Re: [fpc-pascal] Parameterless constructors are not allowed in records or record/type helpers

[Sven Barth]

Am 05.02.2017 15:04 schrieb "Ryan Joseph" :
>
> I never knew Pascal had default parameters, a feature I always use and
enjoy in PHP. Once again I learn something new about the language I use. :)

I suggest you to read through the language reference guide then ;)

> However, the constructor with default params does not work. I get the
same error as before. {$modeswitch advancedrecords} is on.

Oh, well, it was worth a shot... Alternatively you could declare a class
function named Create that returns an instance of the record. Even Delphi
is using that for Rtti.TRttiContext.

Regards,
Sven
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Re: [fpc-pascal] Parameterless constructors are not allowed in records or record/type helpers

[Maciej Izak]

2017-02-05 14:34 GMT+01:00 Ryan Joseph :

> However, the constructor with default params does not work. I get the same
> error as before. {$modeswitch advancedrecords} is on.
>
> type
> MyRecord = record
> x: integer;
> constructor Foo (_x: integer = 0);
> end;
>

AFAIK this is by design. In theory "constructor Create;" is reserved for
record "Initializers" (which means initialization for managed fields of
record). Parameter less constructor doesn't have much sense for records.
Use "class function Foo: MyRecord ;" instead. Probably syntax "constructor
Create;" will be used for record initializers in next Delphi releases
(around 2018?). In FPC we have implemented this feature (not merged yet :
http://bugs.freepascal.org/view.php?id=30687 ) but as "class operator
Initialize(var a: MyRecord);".

-- 
Best regards,
Maciej Izak
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Re: [fpc-pascal] Parameterless constructors are not allowed in records or record/type helpers

[Ryan Joseph]

I never knew Pascal had default parameters, a feature I always use and enjoy in 
PHP. Once again I learn something new about the language I use. :)

However, the constructor with default params does not work. I get the same 
error as before. {$modeswitch advancedrecords} is on.

type
MyRecord = record
x: integer;
constructor Foo (_x: integer = 0);
end;


> On Feb 5, 2017, at 8:29 PM, Sven Barth  wrote:
> 
> See here at the bottom: 
> http://freepascal.org/docs-html/current/ref/refsu65.html#x176-19800014.4.1 
> (it's the same for any kind of routine: function, procedure, method, 
> constructor...)

Regards,
Ryan Joseph

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Re: [fpc-pascal] Parameterless constructors are not allowed in records or record/type helpers

[Sven Barth]

Am 05.02.2017 09:39 schrieb "Ryan Joseph" :
>
>
> > On Feb 5, 2017, at 3:27 PM, Sven Barth 
wrote:
> >
> > constructor with a default parameter.
>
> How? never heard of this. Thanks.

See here at the bottom:
http://freepascal.org/docs-html/current/ref/refsu65.html#x176-19800014.4.1
(it's the same for any kind of routine: function, procedure, method,
constructor...)

Regards,
Sven
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Re: [fpc-pascal] Parameterless constructors are not allowed in records or record/type helpers

[Ryan Joseph]

> On Feb 5, 2017, at 3:27 PM, Sven Barth  wrote:
> 
> constructor with a default parameter.

How? never heard of this. Thanks.

Regards,
Ryan Joseph

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Re: [fpc-pascal] Parameterless constructors are not allowed in records or record/type helpers

[Sven Barth]

Am 05.02.2017 09:13 schrieb "Ryan Joseph" :
>
> Why is this restriction in place and what are the alternatives if any?
Some times I want to just provide a method that sets default values for a
record without any parameters but FPC doesn’t let me for some reason.

Delphi compatibility.
As a workaround you could add a constructor with a default parameter.

Regards,
Sven
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