Next: Index Up: 2 Reference : The Previous: 13. The system unit
It redefines some basic pascal types, introduces some functions for compatibility with Delphi's system unit, and introduces some methods for the management of the resource string tables.
type smallint = system.integer; integer = system.longint;The resource string tables can be managed with a callback function which the user must provide: TResourceIterator.
Type
TResourceIterator =
Function (Name,Value : AnsiString;Hash : Longint):AnsiString;
It is most likely introduced to avoid confusion between the regular Assign function and the Assign method of TPersistent in the Delphi VCL.
Program Example88;
{ Program to demonstrate the AssignFile and CloseFile functions. }
{$MODE Delphi}
Var F : text;
begin
AssignFile(F,'textfile.txt');
Rewrite(F);
Writeln (F,'This is a silly example of AssignFile and CloseFile.');
CloseFile(F);
end.
It is most likely introduced to avoid confusion between the regular Close function and the Close method of TForm in the Delphi VCL.
for an example, see AssignFile.
be sure not to release memory that was not obtained with the Getmem call in Objpas. Normally, this should not happen, since objpas changes the default memory manager to it's own memory manager.
Program Example89;
{ Program to demonstrate the FreeMem function. }
{$Mode Delphi}
Var P : Pointer;
begin
Writeln ('Memory before : ',Memavail);
GetMem(P,10000);
FreeMem(P);
Writeln ('Memory after : ',Memavail);
end.
Be sure to release this memory with the FreeMem call defined in the objpas unit.
For an example, see FreeMem.
The current value depends on the system of internationalization that was used, and which language is selected when the program is executed.
Program Example90;
{ Program to demonstrate the GetResourceStringCurrentValue function. }
{$Mode Delphi}
ResourceString
First = 'First string';
Second = 'Second String';
Var I,J : Longint;
begin
{ Print current values of all resourcestrings }
For I:=0 to ResourceStringTableCount-1 do
For J:=0 to ResourceStringCount(i)-1 do
Writeln (I,',',J,' : ',GetResourceStringCurrentValue(I,J));
end.
The default value is the value of the string that appears in the source code of the programmer, and is compiled into the program.
Program Example91;
{ Program to demonstrate the GetResourceStringDefaultValue function. }
{$Mode Delphi}
ResourceString
First = 'First string';
Second = 'Second String';
Var I,J : Longint;
begin
{ Print default values of all resourcestrings }
For I:=0 to ResourceStringTableCount-1 do
For J:=0 to ResourceStringCount(i)-1 do
Writeln (I,',',J,' : ',GetResourceStringDefaultValue(I,J));
end.
The hash value is calculated from the default value of the resource string in a manner that gives the same result as the GNU gettext mechanism. It is stored in the resourcestring tables, so retrieval is faster than actually calculating the hash for each string.
For an example, see Hash.
If a unit MyUnit declares a resourcestring MyTitle then the name returned will be myunit.mytitle. A resourcestring in the program file will have the name of the program prepended.
The name returned by this function is also the name that is stored in the resourcestring file generated by the compiler.
Strictly speaking, this information isn't necessary for the functioning of the program, it is provided only as a means to easier translation of strings.
Program Example92;
{ Program to demonstrate the GetResourceStringName function. }
{$Mode Delphi}
ResourceString
First = 'First string';
Second = 'Second String';
Var I,J : Longint;
begin
{ Print names of all resourcestrings }
For I:=0 to ResourceStringTableCount-1 do
For J:=0 to ResourceStringCount(i)-1 do
Writeln (I,',',J,' : ',GetResourceStringName(I,J));
end.
Program Example93;
{ Program to demonstrate the Hash function. }
{$Mode Delphi}
ResourceString
First = 'First string';
Second = 'Second String';
Var I,J : Longint;
begin
For I:=0 to ResourceStringTableCount-1 do
For J:=0 to ResourceStringCount(i)-1 do
If Hash(GetResourceStringDefaultValue(I,J))
<>GetResourceStringHash(I,J) then
Writeln ('Hash mismatch at ',I,',',J)
else
Writeln ('Hash (',I,',',J,') matches.');
end.
The zeroeth command-line parameter contains the path of the executable, except on LINUX, where it is the command as typed on the command-line.
For an example, see Paramstr.
Normally, this should never be called from a user's program. It is called in the initialization code of the objpas unit. However, if the resourcetables get messed up for some reason, this procedure will fix them again.
For an example, see GetResourceStringDefaultValue
The tables are numbered from 0 to ResourceStringTableCount-1, i.e. they're zero based.
For an example, see GetResourceStringDefaultValue
Procedure SetResourceStrings (SetFunction : TResourceIterator);
The Name,Value and Hash parameters passed to the iterator function are the values stored in the tables.
Program Example95;
{ Program to demonstrate the SetResourceStrings function. }
{$Mode objfpc}
ResourceString
First = 'First string';
Second = 'Second String';
Var I,J : Longint;
S : AnsiString;
Function Translate (Name,Value : AnsiString; Hash : longint): AnsiString;
begin
Writeln ('Translate (',Name,') => ',Value);
Write ('->');
Readln (Result);
end;
begin
SetResourceStrings(@Translate);
Writeln ('Translated strings : ');
For I:=0 to ResourceStringTableCount-1 do
For J:=0 to ResourceStringCount(i)-1 do
begin
Writeln (GetResourceStringDefaultValue(I,J));
Writeln ('Translates to : ');
Writeln (GetResourceStringCurrentValue(I,J));
end;
end.
Program Example94;
{ Program to demonstrate the SetResourceStringValue function. }
{$Mode Delphi}
ResourceString
First = 'First string';
Second = 'Second String';
Var I,J : Longint;
S : AnsiString;
begin
{ Print current values of all resourcestrings }
For I:=0 to ResourceStringTableCount-1 do
For J:=0 to ResourceStringCount(i)-1 do
begin
Writeln ('Translate => ',GetResourceStringDefaultValue(I,J));
Write ('->');
Readln(S);
SetResourceStringValue(I,J,S);
end;
Writeln ('Translated strings : ');
For I:=0 to ResourceStringTableCount-1 do
For J:=0 to ResourceStringCount(i)-1 do
begin
Writeln (GetResourceStringDefaultValue(I,J));
Writeln ('Translates to : ');
Writeln (GetResourceStringCurrentValue(I,J));
end;
end.