Delphi - connecting similar procedures -

i working on 1 little bit complex application , have found 1 problem. going try reduce complexity of application 1 simple application, example. point is, have 16 regions , there variables , procedures each 1 of them. each procedure have universal each region. resolve writing 1 "if" on beginning of procedure , them copy 15 times bellow , changing little bit, because each region makes difference in few words. have change word in each 1 of them. makes code sooo unclear , wasting of time. there way, how write 16 "ifs" one? using template or that?

example application:

key code:

procedure tform1.writeitem; var item:integer; begin   if currentfile='firstfile' begin     seek(firstfile,filesize(firstfile)-1);     read(firstfile,item);     inc(item);     write(firstfile,item);   end;    if currentfile='secondfile' begin     seek(secondfile,filesize(secondfile)-1);     read(secondfile,item);     inc(item);     write(secondfile,item);   end; end; 

full version:

https://drive.google.com/drive/folders/0bzhr4bza5ibuazjux0fwqzbxchm?usp=sharing

i guessing firstfile, secondfile , on of type tfile or descendant of it, first change make make 'currentfile' of same type (or ancestor of it). then, instead of setting currentfile string, put like

currentfile := fifthfile; 

for instance.

then procedure becomes

procedure tform1.writeitem; var item:integer; begin   seek(currentfile,filesize(currentfilefile)-1);   read(currentfile,item);   inc(item);   write(currentfile,item); end; 

better, though, pass file parameter, this

procedure tform1.writeitem( const curremtfile : tyourfiletype); var item:integer; begin   seek(currentfile,filesize(currentfilefile)-1);   read(currentfile,item);   inc(item);   write(currentfile,item); end; 

edit

as pointed out in comments, procedure not required object variables (although real procedure may). can make independent of object 1 of 2 ways: either move function out of object altogether

procedure writeitem( const curremtfile : tyourfiletype); 

or make class procedure

class procedure tform1.writeitem( const curremtfile : tyourfiletype); 

as general principle prefer latter method, move different class designed handle type of functionality (not form).