[fpc-pascal] Default value for an open array

2012-06-01 Thread Mark Morgan Lloyd 

It's previously been pointed out to me that a declaration such as

procedure OutputWriteF(const str: widestring; values: array of 
const; fg: TColor= clBlack; bg: TColor= clDefault);


can't be rewritten

type owfArray: array of const;
procedure OutputWriteF(const str: widestring; values: owfArray; fg: 
TColor= clBlack; bg: TColor= clDefault);


since this would make the parameter into a dynamic rather than an open 
array. I'm entirely happy to accept that now that I understand it.


However, given a declaration of that form, is it possible to define a 
default parameter of [] so that  OutputWriteF('Test, no params\n')  is 
valid?


--
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]
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Re: [fpc-pascal] Default value for an open array

2012-06-01 Thread kyan 
 However, given a declaration of that form, is it possible to define a
 default parameter of [] so that  OutputWriteF('Test, no params\n')  is
 valid?

Not for open arrays, but you can write an overloaded version without
the open array argument that calls the version with the open array
parameter passing an empty array, or an array initialised with
whatever default values you want:

interface

procedure OutputWriteF(const str: widestring); overload;
procedure OutputWriteF(const str: widestring; values: array of const); overload;

implementation

procedure OutputWriteF(const str: widestring);
begin
  OutputWriteF(str, [clBlack, clDefault]);
end;

procedure OutputWriteF(const str: widestring; values: array of const);
begin
 ...
end;

HTH

Constantine.
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Re: [fpc-pascal] Default value for an open array

2012-06-01 Thread Mark Morgan Lloyd 

kyan wrote:

However, given a declaration of that form, is it possible to define a
default parameter of [] so that  OutputWriteF('Test, no params\n')  is
valid?


Not for open arrays, but you can write an overloaded version without
the open array argument that calls the version with the open array
parameter passing an empty array, or an array initialised with
whatever default values you want:


Thanks, good point and adequate workaround.

--
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]
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