[SOLVED] Howto use a DEFINE present in an installed package

[tintinux]

Hi

I have installed the package ZeosLib in the EDI.
In my projects, I need to know and test the version installed, to make them more independent of the package version and avoid compatibility breaks.

In a source of the ZeosLib package (Zeos.inc) there is

Code: Pascal  [Select][+][-]

1. {$DEFINE ZEOS80UP}

which could help me if I could write in my projects

Code: Pascal  [Select][+][-]

1. {$IF ZEOS80UP}
2. // Code for 8.0
3. {$ELSE}
4. // Code for older version
5. {$ENDIF}

Before, I have to add in my source

Code: Pascal  [Select][+][-]

1. {$I  zeosfolder/Zeos.inc}

But, the exact root path of the package sources (zeosfolder) can change on every installation.
Is there not a way to know where are the source of the installed package, or a way to find them without adding a hard coded path in the options ?

Thanks for your suggestions.

[Of course, this is a general issue, not a ZeosLib issue]

[MarkMLl]

I don't think you can. you can check for a {$define ... } in the same unit using {$ifdef ... } (where the define might actually be in a .inc file), but the best you can do across units is using {$if declared( ... ) } at compilation time, or a version-returning function at runtime.

MarkMLl

[TRon]

You can set a specific include dir to search in in the project options.

Another suggestion might be to add the define to the compiler options in case it is sure that the version matches.

[tintinux]

You can set a specific include dir to search in in the project options.

Another suggestion might be to add the define to the compiler options in case it is sure that the version matches.

No, this is what I would like to avoid : specific include directory or specific compiler option.
I wondered whether if the compiler could find the directory where the package sources have been downloaded, or the version of the package.
Thanks

[MarkMLl]

The compiler doesn't /find/ anything, it needs to be told about paths either on the command line or in fpc.cfg.

In principle you can put a path in either a uses clause or in an include directive. However experience shows that this is risky: there is a problem that's never been made adequately reproducible either in FPC or possibly the Lazarus IDE whereby it doesn't notice that a unit has changed and refuses to recompile it.

I've also seen situations where if you pull in a single include file it insists on recompiling a whole lot of stuff that shouldn't be. That might be specific to some versions of the Lazarus IDE, or might be related to the above problem.

As far as I am aware, you can't specify the value of a define on the command line: it has to be there or not there.

So it boils down to the fact that either you have to use something like

Code: Pascal  [Select][+][-]

1. (* This is an experimental replacement for the RTL's Now() based on the POSIX
2.   clock.
3. *)
4. function posixNow(): TDateTime;
5.  
6. var     ts: timespec;
7.         days: extended;
8.  
9. begin
10.   result := UnixEpoch;
11.  
12. (* This test appears to be unreliable for functions provided directly by the *)
13. (* kernel or a standard system library.                                      *)
14.  
15. {$if defined(clock_gettime) }
16.   if clock_gettime(CLOCK_REALTIME, @ts) = 0 then begin
17.     days := ts.tv_sec / SecsPerDay;
18.     days += ts.tv_nsec / SecsPerDay / 10E9;
19.  
20. (* Since even the extended type doesn't really have enough digits to express *)
21. (* times relative to the unix epoch in nanoseconds, assume we have to be     *)
22. (* very careful with the evaluation order.                                   *)
23.  
24.     result := days + UnixDateDelta
25.   end
26. {$endif                     }
27. end { posixNow } ;
28.  

or you have to use an external tool to build a compiler/project configuration, plus possibly a .inc file containing macros of the various things you need.

MarkMLl

[CharlyTango]

which could help me if I could write in my projects

Code: Pascal  [Select][+][-]

1. {$IF ZEOS80UP}
2. // Code for 8.0
3. {$ELSE}
4. // Code for older version
5. {$ENDIF}

ZEOS provides a version-variable you can use:

Code: Pascal  [Select][+][-]

1.     if (ZEOS_MAJOR_VERSION >= 8) then
2.        //code for 8.0 following
3.     else
4.       // Code for older version
5.     ;

[MarkMLl]

ZEOS provides a version-variable you can use:

Code: Pascal  [Select][+][-]

1.     if (ZEOS_MAJOR_VERSION >= 8) then
2.        //code for 8.0 following
3.     else
4.       // Code for older version
5.     ;

That's not a compile-time operation, so is NBG if he wants to refer to things which exist only in a later (or earlier) version or have different parameter lists etc.

MarkMLl

[marcov]

If it is a proper constant you can also test them with $if

[tintinux]

That's not a compile-time operation, so is NBG if he wants to refer to things which exist only in a later (or earlier) version or have different parameter lists etc.

Yes !

If it is a proper constant you can also test them with $if

How ?

[Remy Lebeau]

If it is a proper constant you can also test them with $if

How ?

Code: Pascal  [Select][+][-]

1. {$IF (ZEOS_MAJOR_VERSION >= 8)}
2. //code for 8.0 following
3. {$ELSE}
4. // Code for older version
5. {$ENDIF}

[tintinux]

Hi

This should be very interesting, but with ZEOS 8.0 installed the test

Code: Pascal  [Select][+][-]

1.  {$IF (ZEOS_MAJOR_VERSION >= 8)}

is wrong.
Was it a mere example ?
Or is there something else to do ?

Thanks

[MarkMLl]

Depends on the mode.

The content of an expression is restricted to what can be evaluated at compile-time:

*    Constants (strings, numbers)
*    Macros
*    Compile time variables (mode MacPas only)
*    Pascal constant expressions (mode Delphi only) <=====

https://www.freepascal.org/docs.html -> Programmer's Guide detailed discussion of $IF. It's safest that I don't put in a URL for that since there's no guarantee that if will remain consistent over different versions of the compiler.

MarkMLl

[Zoran]

Hi

This should be very interesting, but with ZEOS 8.0 installed the test

Code: Pascal  [Select][+][-]

1.  {$IF (ZEOS_MAJOR_VERSION >= 8)}

is wrong.
Was it a mere example ?
Or is there something else to do ?

Thanks

It is not wrong provided that this is a true constant (not a typed constant). And it is, as we can see: https://sourceforge.net/p/zeoslib/code-0/HEAD/tree/trunk/src/core/ZClasses.pas#l65

That is of course, provided the unit where it is declared is added in uses section. You added it, didn't you? Which error do you get?

[tintinux]

Sorry, I was meaning False, not Wrong.

Even with referring ZClasses in the uses clause (where the const ZEOS_MAJOR_VERSION  is defined in the interface part) the condition is negative.

I don't understand...

Code: Pascal  [Select][+][-]

1. interface
2.  
3. uses
4.   Classes,
5.   SysUtils,
6.   LResources,
7.   Forms,
8.   Controls,
9.   DB,
10.   ZClasses;
11.  
12.  type
13.   {$IF (ZEOS_MAJOR_VERSION >= 8)}
14.      // greyed (not compiled)
15.   {$ELSE}
16.     // black (compiled)
17.   {$ENDIF}

[marcov]

The syntax highlighter and the compiler can differ in opinion. Make sure you test it by running a compiled binary and printing or logging the result.