Hi,

Based on the latest FPC Language Reference documentation, there is no "library" hint directive (like Delphi & Kylix has)...

http://www.freepascal.org/docs-html/ref/refse5.html#x17-160001.5

Or Section 1.5 on page 16 of the PDF.

Yet the following example program compiles without error using FPC 2.6.4. I gather this is an omission in the documentation?

Second question, what does the "library" hint directive mean or do?

=========================================
program test;
{$mode objfpc}{$h+}
uses
  SysUtils, Classes;
var
  VersionNumber: Real library;
begin
  VersionNumber := 1.234;
  writeln(VersionNumber);
end.

=========================================

Regards,
- Graeme -

Good question. It's the first time I heard of the 'library' directive.

Michael.

In our previous episode, Graeme Geldenhuys said:

http://docwiki.embarcadero.com/RADStudio/Seattle/en/Declarations_and_Statements

A lot of the later ones were added in one go, not all might be implemented. Seems it is only meant to flag functions as potentially os dependent, similar to platform.

Another such one is experimental.

Quote from above link:

Use platform to mark items that are specific to a particular operating environment (such as Windows), deprecated to indicate that an item is obsolete or supported only for backward compatibility, and library to flag dependencies on a particular library or component framework.

(MvdV: read: VCL vs CLX)

The Delphi compiler also recognizes the hinting directive experimental. You can use this directive to designate units that are in an unstable development state. The compiler will emit a warning when it builds an application that uses the unit.

Michael Van Canneyt wrote

Good question. It's the first time I heard of the 'library' directive.

The Delphi documentation is very vague too.

http://docwiki.embarcadero.com/RADStudio/Seattle/en/Declarations_and_Statements#Hinting_Directives

Regards,
- Graeme -

Marco van de Voort wrote

http://docwiki.embarcadero.com/RADStudio/Seattle/en/Declarations_and_Statements

To follow on from your quotes....

"The platform and library directives do not specify which platform or library. If your goal is writing platform-independent code, you do not need to know which platform a symbol is specific to; it is sufficient that the symbol be marked as specific to some platform to let you know it may cause problems for your goal of portability."

I guess with the above description IFDEF's will most likely be the better option in real-world code.

Regards,
- Graeme -

In our previous episode, Graeme Geldenhuys said:

Those were always more to aid with the VCL->CLX transition or cohabitation.

Those share many common method names, but directives like this allowed to ban/flag some of them (like gethandle, windowhandle etc), making it easier to upgrade/prepare vcl codebases to CLX.

Deprecated and platform are a bit more generic.

Experimental is mainly to make absolutely clear that not anything published is definitive. IMHO should be used more often.

"Marco van de Voort" wrote

Experimental is mainly to make absolutely clear that not anything

published

is definitive. IMHO should be used more often.

I definitely agree here. ^^

Regards,
Sven