Disturbing, but save in an archive instead

Preben Alsholm — Wed, 01 Sep 2010 13:36:30 Z

It is rather curious, indeed. And disturbing!

Apparently by saving the module in the second example mp:-mult evaluates to the global variable mult, which has not been defined to be anything.

If inside the procedure f2, mult is replaced by mp:-mult, then both versions work, also after saving.

However, if you create a Maple archive and save your packages there, both seem to work fine:

restart;
#mkdir("F:/temp");
march(create,"F:/temp/mp.mla",10);
restart;
mp1:= module()
export mult, f2; option package;
mult:=proc(v) 3*v end proc;
f2 :=proc(v) mult(v); end proc;
end module;
savelibname:="F:/temp/mp.mla";
savelib(mp1);
restart;
libname := libname, "F:/temp";

with(mp1);
f2(5);
mult(4);

restart;
mp2:= module() export f2, mult; option package;
mult:=proc(v) 3*v end proc;
f2 :=proc(v) mult(v) end proc;
end module;

savelibname:="F:/temp/mp.mla";
savelib(mp2);

restart;
libname := "F:/temp",libname;

with(mp2);
f2(5);
mult(4);

Library archive (.mla repository)

acer — Wed, 01 Sep 2010 19:24:22 Z

As a general rule, a module has to be savelib'd to a .mla Library archive (repository) and not to a .m file, if it is to be saved fully intact.

If there is no writable .mla archive in the savelibname (or libname) path then Maple will write out to a .m ("dotm") format file instead.

And, in general, a module is not fully encapsulated when saved to a .m file. That should be better documented. But there it is.

Workarounds are to either assign savelibname to a particular .mla filename, or to a directory which contains a writable .mla archive. That's good practice in general, or else lots of savelib() calls will litter some directory instead of nicely saving any individual .m's to a .mla container.

FWIW, that is related to why customized context-menu actions do not work properly on modules as the display output. The GUI-kernel interaction for it is somehow dotm based, and only a shell of the module object gets received by the context-menu package's code. This is a shame, given how long modules have been in Maple.

The Example in ?LibraryTools,Create should use the currently supported .mla and not the old deprecated .lib/.ind filename extensions.

It might be better if the tools were more user-friendly. The `savelib` command could issue an error if no writable archive were present, and suggest using `save` instead. The `save` command could issue an error if told to save a module whichit could not fully handle. And so on. I bet something better is workable, while only losing "misfunctionality".

acer

MaplePrimes - answers and comments on Question, sequence of export variables in a module matter

Disturbing, but save in an archive instead

Library archive (.mla repository)