Problem with c style macros

[Чебурашка]

Code: Pascal  [Select][+][-]

1. program testmacro;
2. uses
3.   Classes, SysUtils;
4. begin
5.   {$MACRO ON}
6.   {$define main_macro_text:=X_, X_D}
7.   Writeln({$define X_:=start}'main_macro_text, ' + {$define X_:=end}'main_macro_text');
8.   {$MACRO OFF}
9. end.
10.  

expected output:

Code: Bash  [Select][+][-]

1. start, startD, end, endD
2.  

actual output:

Code: Bash  [Select][+][-]

1. main_macro_text, main_macro_text
2.  

What am I doing wrong?

[TRon]

What am I doing wrong?

You are not doing anything wrong.

Free Pascal does not support macro parameters, at least not in the way you seem to think it does. Macro features for Free Pascal are very limited, see also https://www.freepascal.org/docs-html/prog/progse5.html

Unfortunately the C-macro you showed can not be converted into a Pascal macro. It is as simple as that.

[Чебурашка]

Yes true.
I also did a more detailed test with C and I got bad results: it doesn't event compile at defines level, not in main_macro_text expression.

Code: C  [Select][+][-]

1. #include <stdio.h>
2.  
3. int main(int argv, char** argc)
4. {
5.     #define X_ start
6.     #define main_macro_text X_, X_D
7.     printf("main_macro_text");
8.    
9.     return 0;
10. }
11.  

Simply my idea how how macros work is wrong, both in C and in FPC.

[Чебурашка]

Instead this does the trick

Code: Pascal  [Select][+][-]

1. program testmacro;
2. uses
3.   Classes, SysUtils;
4. begin
5.   {$MACRO ON}
6.   {$define main_macro_text:=X_ + ', ' + X_ + 'D'}
7.   Writeln({$define X_:='start'}main_macro_text + ', ' + {$define X_:='end'}main_macro_text);
8.   Writeln({$define X_:='end'}main_macro_text + ', ' + {$define X_:='start'}main_macro_text);
9.   {$MACRO OFF}
10. end.
11.  

Code: Bash  [Select][+][-]

1. start, startD, end, endD
2. end, endD, start, startD
3.  

But this does not create the string at compile time, it does the operation on the code during runtime, not what I wanted.

 :'(

[ASerge]

Macros only confuse the code.

Code: Pascal  [Select][+][-]

1. {$APPTYPE CONSOLE}
2.  
3. function DoubleWithD(const S: string): string;
4. begin
5.   Result := S + ', ' + S + 'D';
6. end;
7.  
8. begin
9.   Writeln(DoubleWithD('start'), ', ', DoubleWithD('end'));
10.   Writeln(DoubleWithD('end'), ', ', DoubleWithD('start'));
11.   Readln;
12. end.

[Zvoni]

Instead this does the trick

Code: Pascal  [Select][+][-]

1. program testmacro;
2. uses
3.   Classes, SysUtils;
4. begin
5.   {$MACRO ON}
6.   {$define main_macro_text:=X_ + ', ' + X_ + 'D'}
7.   Writeln({$define X_:='start'}main_macro_text + ', ' + {$define X_:='end'}main_macro_text);
8.   Writeln({$define X_:='end'}main_macro_text + ', ' + {$define X_:='start'}main_macro_text);
9.   {$MACRO OFF}
10. end.
11.  

Code: Bash  [Select][+][-]

1. start, startD, end, endD
2. end, endD, start, startD
3.  

But this does not create the string at compile time, it does the operation on the code during runtime, not what I wanted.

 :'(

You're trying to "stringify" some strings.
As i said before: C-Programmers are lazy buggers.
Stuff like that always confused the hell out of me
Write it out and be done with it.

btw: What exactly are you trying to achieve?

[Чебурашка]

btw: What exactly are you trying to achieve?

Maybe I am actually looking for trouble, but the intent was create a set of sql¹ view creation statements similar but not equal (similar processing on different field name) in a consistent way, so the if in future I need to extend (as it happened already) I can make it in a single place and have them updated safely/consistently everywhere.

I will make it in a runtime way using SysUtils.Format, but I am partly unhappy with this because these strings are compile time. I will not tell my daughter about that.


¹ ORM is the Viet Nam of computer science (cit.)


A very small extract of what I am doing here:

Code: Pascal  [Select][+][-]

1.   viewFieldsFrag          := 'startDate   , startDateS                                              , startDateSM                                 , startDateSW                                                                                             , startDateSD                                     , startDateSH                                       , endDate, endDateS                                           , endDateSM                              , endDateSW                                                                                       , endDateSD                                 , endDateSH                                    ';
2.   viewQuerySQLiteFrag     := 'startDate   , strftime(''%Y-%m-%d %H:%M:%S'', startDate)              , strftime(''%Y-%m'', startDate)              , strftime(''%Y-%W'', startDate)                                                                          , strftime(''%Y-%m-%d'', startDate)               , strftime(''%Y-%m-%d %H'', startDate)              , endDate, strftime(''%Y-%m-%d %H:%M:%S'', endDate)           , strftime(''%Y-%m'', endDate)           , strftime(''%Y-%W'', endDate)                                                                    , strftime(''%Y-%m-%d'', endDate)           , strftime(''%Y-%m-%d %H'', endDate)           ';
3.   viewQueryPostgreSQLFrag := 'startDate   , to_char(startDate, ''YYYY-MM-DD HH24:MI:SS'')           , to_char(startDate, ''YYYY-MM'')             , to_char(startDate, ''YYYY-WW'')                                                                         , to_char(startDate, ''YYYY-MM-DD'')              , to_char(startDate, ''YYYY-MM-DD HH24'')           , endDate, to_char(endDate, ''YYYY-MM-DD HH24:MI:SS'')        , to_char(endDate, ''YYYY-MM'')          , to_char(endDate, ''YYYY-WW'')                                                                   , to_char(endDate, ''YYYY-MM-DD'')          , to_char(endDate, ''YYYY-MM-DD HH24'')        ';
4.   viewQuerySQLServerFrag  := 'startDate   , format(startDate, ''yyyy-MM-dd hh:mm:ss'', ''en-US'')   , format(startDate, ''yyyy-MM'', ''en-US'')   , concat(format(startDate, ''yyyy-'', ''en-US''), cast(datepart(iso_week, startDate) as varchar(2)))      , format(startDate, ''yyyy-MM-dd'', ''en-US'')    , format(startDate, ''yyyy-MM-dd hh'', ''en-US'')   , endDate, format(endDate, ''yyyy-MM-dd hh:mm:ss'', ''en-US''), format(endDate, ''yyyy-MM'', ''en-US''), concat(format(endDate, ''yyyy-'', ''en-US''), cast(datepart(iso_week, startDate) as varchar(2))), format(endDate, ''yyyy-MM-dd'', ''en-US''), format(endDate, ''yyyy-MM-dd hh'', ''en-US'')';
5.   {%REGION 'V1101_RepCache_PowerOns' /fold}
6.   dbo := TDBObjectsEnum.dbo__V1101_RepCache_PowerOns;
7.   BlankTLiquibaseCreationScriptsDBDependent(lqds);
8.   lqds[TMEPLiquibaseDatabaseType.ldtSQLite] :=       '<createView fullDefinition="true" viewName="V1101_RepCache_PowerOns">' + LineEnding
9.                                                    + 'create view V1101_RepCache_PowerOns(machine   , id, ' + viewFieldsFrag + ', durationSeconds, durationMinutes    , durationHours       , totalEnergyWh, totalEnergykWh      )' + LineEnding
10.                                                    + ' as select                          refMachine, id, ' + viewQuerySQLiteFrag + ', durationSeconds, durationSeconds/60 , durationSeconds/3600, totalEnergyWh, totalEnergyWh / 1000 from T1101_RepCache_PowerOns' + LineEnding
11.                                                    + '</createView>' + LineEnding;
12.   lqds[TMEPLiquibaseDatabaseType.ldtPostgreSQL] :=   '<createView fullDefinition="true" viewName="V1101_RepCache_PowerOns">' + LineEnding
13.                                                    + 'create view V1101_RepCache_PowerOns(machine   , id, ' + viewFieldsFrag + '         , durationSeconds, durationMinutes   , durationHours       , totalEnergyWh, totalEnergykWh     )' + LineEnding
14.                                                    + ' as select                          refMachine, id, ' + viewQueryPostgreSQLFrag + ', durationSeconds, durationSeconds/60, durationSeconds/3600, totalEnergyWh, totalEnergyWh/1000 from T1101_RepCache_PowerOns' + LineEnding
15.                                                    + '</createView>' + LineEnding;
16.   lqds[TMEPLiquibaseDatabaseType.ldtSQLServer] :=    '<createView fullDefinition="true" viewName="V1101_RepCache_PowerOns">' + LineEnding
17.                                                    + 'create view V1101_RepCache_PowerOns(machine   , id, ' + viewFieldsFrag + '         , durationSeconds, durationMinutes   , durationHours       , totalEnergyWh, totalEnergykWh     )' + LineEnding
18.                                                    + ' as select                          refMachine, id, ' + viewQuerySQLServerFrag +  ', durationSeconds, durationSeconds/60, durationSeconds/3600, totalEnergyWh, totalEnergyWh/1000 from T1101_RepCache_PowerOns' + LineEnding
19.                                                    + '</createView>' + LineEnding;
20.  
21.   DBObjectDescriptors[dbo] := TDBObjectDescriptor.CreateView({Name}'V1101_RepCache_PowerOns',
22.   {CreateScript}  'create view V1101_RepCache_PowerOns                             '
23.                 + '(                                                                     '
24.                 + '        machine    , id, startDateS                                , startDateSD                      , startDateSH                         , endDateS                                , endDateSD                      , endDateSH                         , durationSeconds, durationMinutes    , durationHours       , totalEnergyWh, totalEnergykWh      '
25.                 + ') '
26.                 + 'as '
27.                 + ' select refMachine , id, strftime(''%Y-%m-%d %H:%M:%S'', startDate), strftime(''%Y-%m-%d'', startDate), strftime(''%Y-%m-%d %H'', startDate), strftime(''%Y-%m-%d %H:%M:%S'', endDate), strftime(''%Y-%m-%d'', endDate), strftime(''%Y-%m-%d %H'', endDate), durationSeconds, durationSeconds/60 , durationSeconds/3600, totalEnergyWh, totalEnergyWh / 1000'
28.                 + ' from T1101_RepCache_PowerOns',
29.   {LiquibaseCreateDBSpecifci}lqds,
30.   {DropScript}'drop view V1101_RepCache_PowerOns');
31.   {%ENDREGION}
32.  

[Zvoni]

Maybe I am actually looking for trouble, but the intent was create a set of sql view creation statements *snipp*

What i thought......
I'm doing something similiar, but i'm using Arrays/Const

Code: Pascal  [Select][+][-]

1. program Project1;
2. Uses SysUtils, Classes;
3.  
4. Const
5.   ViewStartEnd: Array[0..3] Of String =  ('start', 'startD', 'end', 'endD');
6.   ViewEndStart: Array[0..3] Of String =  ('end', 'endD', 'start', 'startD');
7.  
8. begin
9.   Writeln(String.Join(', ',ViewStartEnd));
10.   Writeln(String.Join(', ',ViewEndStart));
11. end.

Returns

Code: [Select]

start, startD, end, endD
end, endD, start, startD

So, basically, instead of fully writing out the Statements, i keep Arrays of those Fields, and then i just choose the Array(s) i need, join them on the fly, and done

Code: Pascal  [Select][+][-]

1. program Project1;
2.  
3. Uses SysUtils, Classes;
4.  
5. Const
6.   FieldsTable:Array[0..1] Of Array[0..2] Of String =
7.     (
8.       ('Table1', 'Column1', 'Column2'),
9.       ('Table2', 'Col1', 'Col2')
10.     );
11. Var
12.   i:Integer;
13. begin
14.   For i:=0 To 1 Do
15.     Writeln('SELECT '+String.Join(', ', FieldsTable[i],1,Length(FieldsTable[i])-1)+' FROM '+FieldsTable[i][0]);
16. end.

[Чебурашка]

So, basically....

I don't want to generate all the DDL like that, I did it in my life, but is difficult to read afterwards.

My problem, is more related to  some parts of sql code that are used multiple times with variations (rdbms oddities) to be managed consistently. Basically I need a templating system for them.
I would like to make it at compile but, even if the macros were supporting it, I realize that is better use the old good Format().

[Zvoni]

So, basically....

I don't want to generate all the DDL like that, I did it in my life, but is difficult to read afterwards.

My problem, is more related to  some parts of sql code that are used multiple times with variations (rdbms oddities) to be managed consistently. Basically I need a templating system for them.
I would like to make it at compile but, even if the macros were supporting it, I realize that is better use the old good Format().

Look again at my Example above.
Instead of the first dimension referencing different tables, you could do something like

Code: Pascal  [Select][+][-]

1.     program Project1;
2.      
3.     Uses SysUtils, Classes;
4.      
5.     Const
6.       FieldsTable:Array[0..1] Of Array[0..1] Of String =
7.         (
8.           ('startDate', 'strftime(''%Y-%m-%d %H:%M:%S'', startDate)'), {For SQLite}
9.           ('startDate', 'to_char(startDate, ''YYYY-MM-DD HH24:MI:SS'')') {For MySQL}
10.         );  
11.     begin
12.         Writeln('For SQLite: ', 'SELECT '+String.Join(', ', FieldsTable[0])+' FROM SomeTable;');
13.         Writeln('For MySQL: ', 'SELECT '+String.Join(', ', FieldsTable[1])+' FROM SomeTable;');
14.     end.
15.  

And then it's just a choice of the correct Index