John Lee wrote 36 lines
Sorry for confusion, my email wasn't clear...
old fpc version, that I have to use because of availability of various
units...Free Pascal Compiler version 2.2.2 [2008/08/03] for i386
this is jim.pp---
unit jim;
interface
function fna:string;
function fnb:string;
implementation
function fna:string;
begin
fna:='jim';
end;
function fnb:string;
begin
fnb:=fna;
end;
end.
this is fred.pp---
uses jim;
function fna:string;
begin
fna:='fred';
end;
begin
writeln(fnb);
end.
This writeln gives jim, ie the version in jim - I'd like it to be fred &
thought that it would! What can I do please, to _force_ fnb to use the
fred version of fna?
As I said per se this is expected, because the "jnb" in "jim" only knows about the "jna" in "jim", but not about the "jna" in your main program.
Possible solution:
Extend your unit "jim" the following way (this is the "function variable" approach I mentioned):
=== unit jim begin ===
unit jim;
interface
type
TStringFunc = function: String;
function fna: String;
function fnb(aFunc: TStringFunc = Nil): String;
implementation
function fna: String;
begin
fna := 'jim';
end;
function fnb(aFunc: TStringFunc): String;
begin
if Assigned(aFunc) then
fnb := aFunc
else
fnb := fna;
end;
end.
=== unit jim end ===
And your main program will then look like this:
=== main program begin ===
uses jim;
function fna: String;
begin
fna := 'fred';
end;
begin
writeln(fnb(@fna)); // will print "fred"
writeln(fnb); // will print "jim"
end.
=== main program end ===
For further information about procedure/function variables I refer you to the documentation:
http://www.freepascal.org/docs-html/ref/refse17.html#x45-520003.6
Of course you are free to ask further questions if you need help on this or another topic. ;)
Regards,
Sven
