[Caml-list] choosing modules at runtime

[Henri Dubois-Ferriere <henridf@lcavsun1.epfl.ch>]

Say I have a module signature M which is implemented by module structs 
M_1, M_2, M_3, .. M_N.

At runtime , depending on some command-line parameters, I will choose one 
of the module implementations (they use different algorithms internally). 

This means my main code will be littered with things like

if (use algorithm 1) then
M_1.run_algo()
else if (use algorithm 2) then
M_2.run_algo() ...

each time I use a function from the signature M. Of course I could do a 
shorthand hack like

let run_algo = 
  if (use algorithm 1) then
  M_1.run_algo
  else if (use algorithm 2) then
  M_2.run_algo ...

and then simply call run_algo from then on. (But this needs to be done for 
every function/value that the signature M exports).

Am I missing something obvious here? Of course what I would conceptually 
like to do would be something like

let Mod = if (use algorithm 1) then M_1 else if (use alg 2) then M_2 ..

and then be able to call Mod.run_algo(), but that probably belies that I 
am still thinking in an OO manner...

Thanks for any hints on the matter.

Henri

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