Improve libGAP startup error handling

[vbraun]

Currently, libGAP doesn't give useful errors if something goes wrong during initialization.

Also, the GAP SIGINT handler got installed, this is fixed in the new spkg. Now Ctrl-C works as expected.

Install ​http://www.stp.dias.ie/~vbraun/Sage/spkg/libgap-4.5.6.p1.spkg

[vbraun]

Miguel, you said that you had some mysterious error. Can you try this patch? It depends on the recently-updated patches on #6391, #13211.

[mmarco]

I have been checking the different updates of libgap, and the error seemed to go away several versions ago. Anyways, i will keep testing it.

[mmarco]

I don't know if it is an issue related with this patch or if it comes from libgap itself, but i have experienced some problems when i use tab completion in a session in the command line (i haven't checked it in the notebook).

An example:

sage: F=libgap.eval('FreeGroup(2)')
sage: (a,b)=F.GeneratorsOfGroup()
sage: H=F/libgap([a^2,b^2,a*b*a*b])
sage: H
<fp group on the generators [ f1, f2 ]>
sage: H.IsomorphismSimplifiedFpGroup()
[ f1, f2 ] -> [ f1, f2 ]
sage: H=F/libgap([a^2,b^2,a*b])    
sage: c=H.Gene
H.GeneralLinearGroup      H.GeneralisedEigenspaces  H.GeneralizedEigenvalues  H.GeneratorsOfIdeal
H.GeneralOrthogonalGroup  H.GeneralisedEigenvalues  H.GeneratorsOfField       
H.GeneralUnitaryGroup     H.GeneralizedEigenspaces  H.GeneratorsOfGroup       
sage: c=H.GeneratorsOfGroup()[0]
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)

/home/mmarco/sage-5.4/<ipython console> in <module>()

/home/mmarco/sage-5.4/local/lib/python2.7/site-packages/sage/libs/gap/element.so in sage.libs.gap.element.GapElement.__getattr__ (sage/libs/gap/element.c:3555)()

AttributeError: Name "GeneratorsOfGroup" is not defined in GAP.
sage: c=H.GeneratorsOfGroup()   
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)

/home/mmarco/sage-5.4/<ipython console> in <module>()

/home/mmarco/sage-5.4/local/lib/python2.7/site-packages/sage/libs/gap/element.so in sage.libs.gap.element.GapElement.__getattr__ (sage/libs/gap/element.c:3555)()

AttributeError: Name "GeneratorsOfGroup" is not defined in GAP.
sage: H
Exception RuntimeError: 'Entered a critical block twice' in 'sage.libs.gap.util.error_handler' ignored
<fp group on the generators [ f1, f2 ]>
sage: H.GeneratorsOfGroup()
[ f1, f2 ]
sage: c=H.GeneratorsOfGroup()[0]
sage: c
f1
sage: c=H.Generat
H.GeneratorsOfField  H.GeneratorsOfGroup  H.GeneratorsOfIdeal  
sage: c=H.GeneratorsOfGroup()
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)

/home/mmarco/sage-5.4/<ipython console> in <module>()

/home/mmarco/sage-5.4/local/lib/python2.7/site-packages/sage/libs/gap/element.so in sage.libs.gap.element.GapElement.__getattr__ (sage/libs/gap/element.c:3555)()

AttributeError: Name "GeneratorsOfGroup" is not defined in GAP.
sage: c=H.GeneratorsOfGroup()
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)

/home/mmarco/sage-5.4/<ipython console> in <module>()

/home/mmarco/sage-5.4/local/lib/python2.7/site-packages/sage/libs/gap/element.so in sage.libs.gap.element.GapElement.__getattr__ (sage/libs/gap/element.c:3555)()

AttributeError: Name "GeneratorsOfGroup" is not defined in GAP.
sage: H
Exception RuntimeError: 'Entered a critical block twice' in 'sage.libs.gap.util.error_handler' ignored
<fp group on the generators [ f1, f2 ]>
sage: c=H.GeneratorsOfGroup()

[mmarco]

This same behaviour appears when i don't use this patch, so reported in the libgap ticket.

[vbraun]

Updated patch fixes the issue with the command line completion

[vbraun]

Updated spkg fixes long input lines (>32k characters):

sage: S = SymmetricGroup(10000)
sage: s = S.random_element()
sage: len(str(s._gap_()))
61673
sage: libgap(s)
(1,5243,8582,5012,6862,7477,1681,7423,8405,3101,...,5257,9362,2495,8500)( [...] )

[vbraun]

I've added the same workaround for the gap command line option issue as just discussed in #13211

[vbraun]

I've added __nonzero__ for wrapped GAP booleans for easier use.

[vbraun]

Updated patch

[vbraun]

The new patch allows to change the comparison method for libgap objects since not all GAP objects can be compared. This is important if you want use them as cache keys.

Also, the comparison was not properly wrapped in sig_on/sig_off

[vbraun]

I forgot to package aclocal.m4, updated spkg adds that file.