Loading HeLP without NormalizInterface or 4ti2Interface results in syntax warnings

[fingolfin]

See the log below.

One fix would be to make NormalizInterface and 4ti2Interface be in NeededOtherPackages instead of SuggestedOtherPackages.

Another would be to move the code invoking NmzCone etc. to a package extension.

Yet another would be to rewrite the code invoking NmzCone etc. to instead use ValueGlobal("NmzCone") etc. (which is clunky of course). Note that the use would still get an error about an undefined global when running that code.

#I  HeLP: PackageAvailabilityInfo: version 4.0 is available
#I  HeLP: start loading needed/suggested/self packages
#I        help
#I  HeLP: start reading file 'init.g'
#I  HeLP: finish reading file 'init.g'
#I  HeLP: start reading file 'read.g'
Syntax warning: Unbound global variable in /home/runner/gap/pkg/help/lib/HeLP_\
internal_functions.gi:232
  D := NmzCone(["inhom_equations", [T_temp], "inhom_inequalities", temptemp]);\
 #Solve the system
       ^^^^^^^
Syntax warning: Unbound global variable in /home/runner/gap/pkg/help/lib/HeLP_\
internal_functions.gi:234
    NmzCompute(D, ["DualMode", "HilbertBasis", "ModuleGenerators", "MaximalSub\
space", "VerticesOfPolyhedron"]);
    ^^^^^^^^^^
Syntax warning: Unbound global variable in /home/runner/gap/pkg/help/lib/HeLP_\
internal_functions.gi:236
    NmzCompute(D, ["DualMode", "HilbertBasis", "ModuleGenerators", "MaximalSub\
space"]);
    ^^^^^^^^^^
Syntax warning: Unbound global variable in /home/runner/gap/pkg/help/lib/HeLP_\
internal_functions.gi:239
  if NmzModuleGenerators(D) = [ ] then       # No solutions at all
     ^^^^^^^^^^^^^^^^^^^
Syntax warning: Unbound global variable in /home/runner/gap/pkg/help/lib/HeLP_\
internal_functions.gi:241
  elif NmzHilbertBasis(D) = [ ] and NmzMaximalSubspace(D) = [ ] then # finitel\
y many solutions
       ^^^^^^^^^^^^^^^
Syntax warning: Unbound global variable in /home/runner/gap/pkg/help/lib/HeLP_\
internal_functions.gi:241
  elif NmzHilbertBasis(D) = [ ] and NmzMaximalSubspace(D) = [ ] then # finitel\
y many solutions
                                    ^^^^^^^^^^^^^^^^^^
Syntax warning: Unbound global variable in /home/runner/gap/pkg/help/lib/HeLP_\
internal_functions.gi:243
    interintersol := NmzModuleGenerators(D);
                     ^^^^^^^^^^^^^^^^^^^
Syntax warning: Unbound global variable in /home/runner/gap/pkg/help/lib/HeLP_\
internal_functions.gi:255
    interintersol := NmzModuleGenerators(D);
                     ^^^^^^^^^^^^^^^^^^^
Syntax warning: Unbound global variable in /home/runner/gap/pkg/help/lib/HeLP_\
internal_functions.gi:257
    if NmzHilbertBasis(D) <> [ ] then
       ^^^^^^^^^^^^^^^
Syntax warning: Unbound global variable in /home/runner/gap/pkg/help/lib/HeLP_\
internal_functions.gi:258
      HB := List(NmzHilbertBasis(D), x -> x{[1..Size(x)-1]});
                 ^^^^^^^^^^^^^^^
Syntax warning: Unbound global variable in /home/runner/gap/pkg/help/lib/HeLP_\
internal_functions.gi:272
  solutions := 4ti2Interface_zsolve_equalities_and_inequalities([ListWithIdent\
icalEntries(Size(T[1]), 1)], [1], temp[1], -temp[2] : precision := HeLP_settin\
gs[3]);
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
#I  HeLP: finish reading file 'read.g'

[wilfwilson]

I've updated your issue to note that the same applies to the 4ti2Interface package (see the last warning).

[fingolfin]

@margollo any chance you'll have time to work on this?

[margollo]

I don't see an ideal solution right now. Will think of it though

[fingolfin]

One way out would be to put this into a package extension. That means the code will get loaded if and only if normalizinterface resp 4ti2interface gets loaded.

This also works "retroactively", i.e. if HeLP is loaded without those package, the functions in the extension won't be around. But if the user loads those packages, they suddenly become available.

So you could have two package extensions, each defining a small helper function... To make it smooth, you could do this:

On the global level:

BindGlobal("_NormalizHelper", function(arg)
  Error("Normaliz not available, please load NormalizInterface");
end);

In the NormalizInterface extension:

MakeReadWriteGlobal("_NormalizHelper")
UnbindGlobal("_NormalizHelper")
BindGlobal("_NormalizHelper", function(arg)
  .... put real code in here.
end);

[margollo]

Thanks, this seems like the best solution! It will need some work though, not only for me to understand its use, but also because the functions using 4ti2 or normaliz are usually the same. Will try to make this happen quickly

[margollo]

To have a better understanding of how it works: which GAP packages do use Extension in this way?

[margollo]

After thinking on the possibilities, I believe the Extensions command is too advanced for what I need. The solution should be restructuring files and then including if-then statements in read.g to load the commands depending on availability of 4ti2 and/or normaliz. Should be done in at most a couple of days

[fingolfin]

Packages using this:

pkg/packagemanager/PackageInfo.g
93:Extensions := [

pkg/modulepresentationsforcap/PackageInfo.g
113:Extensions := [

pkg/linearalgebraforcap/PackageInfo.g
112:Extensions := [

pkg/example/PackageInfo.g
385:##  see Section "Extensions Provided by a Package" in the GAP Reference Manual.
394:##  can be specified via the 'Extensions' component.
396:##  Extensions are supported since GAP 4.13 or later, older GAP versions will
398:# Extensions := [],

pkg/cap/PackageInfo.g
123:Extensions := [

pkg/browse/PackageInfo.g
58:Extensions := [

pkg/ctbllib/PackageInfo.g
139:Extensions := [

pkg/atlasrep/PackageInfo.g
160:Extensions := [

I am not sure why you consider this advanced. The solution you describe is certainly inferior; we introduced extensions specifically to avoid such things.

Anyway, if you can whip up a solution as you describe, I can suggest how to convert it into an extension - it usually is a matter of just a few minutes work.

[margollo]

I just pushed version 4.1. Let's hope it will pass the tests and solve the issue

[fingolfin]

I can make a PR this weekend or next week to change this to use the package extension mechanism which is much more user friendly

[margollo]

Thanks! The reason I chose not to use Extensions is that I was not sure that the three cases "only 4ti2 loads/only normaliz loads/both load" can be made mutually exclusive that way. There is only one function which is concerned, but redefining a global function seemed a bad idea to me.