Merge pull request #649 from zickgraf/category_as_first_argument

Allow to pass the category as the first argument to any CAP operation

CAP/PackageInfo.g

@@ -21,7 +21,7 @@ Version := Maximum( [
   ## this line prevents merge conflicts
   "2020.04-16", ## Sepp's version
   ## this line prevents merge conflicts
-  "2020.10-01", ## Fabian's version
+  "2021.03-01", ## Fabian's version
   ## this line prevents merge conflicts
   "2020.08-01", ## Kamal's version
 ] ),

CAP/doc/AddFunctions.autodoc

@@ -122,8 +122,11 @@ The record can have the following components, used as described:
 * post_function (optional): A function which is used as the postfunction of the installed methods, as described above.
 
 * filter_list: A list containing the basic filters for the methods installed by the add methods. Possible entries are filters, or
-               the following strings, which will be replaced by appropriate filters at the time the add method is called.
+               the strings listed below, which will be replaced by appropriate filters at the time the add method is called.
                Additionally, an entry can be a list consisting of filters and/or the given strings, which will then be joined via `and` to form a single filter.
+               If the first filter is <C>category</C> and the category can be inferred from the remaining arguments, a convenience method without the category
+               as the first argument is installed automatically. Additionally, the category is not passed to primitively added functions, except if
+               `category!.category_as_first_argument` is set to `true` (this will probably change to be the default in the future).
                * <C>category</C>,
                * <C>cell</C>,
                * <C>object</C>,
@@ -146,11 +149,6 @@ The record can have the following components, used as described:
 * cache_name (optional): The name of the cache which is used for the installed methods. If no cache name is given, the caching
                          for the operation is deactivated completely.
 
-* argument_list (optional): A list containing integers, which defines which arguments should be used for the additional functions, (e.g redirect, pre, ...).
-                            This is important for the Op method contructions. If no argument list is given, all arguments are used.
-                            Please note that if you have a method selection argument for your function, you need to give the argument_list
-                            to explicitly state which argument is the method selection argument.
-
 * return_type: The return type can either be a filter or one of the strings in the list below.
                For objects, morphisms and $2$-cells the correct <C>Add</C> function (see above) is
                used for the result of the computation. Otherwise, no <C>Add</C> function is used after all.
@@ -187,19 +185,9 @@ The function CAP_INTERNAL_ENHANCE_NAME_RECORD can be applied to a method name re
 
 * Function name: Set the component function_name to the entry name.
 
-* Redirect and post functions: Since the redirect and post functions need the category to work correctly, the given functions in the method records are
-            packed up to discard the first argument (which is the category) if necessary.
-
-* universal_object_arg_list: An argument list for redirect and post functions is created, by looking at the filter list in the record.
-            If the number of diagram arguments is zero, the first argument is used.
-            If all diagram arguments are lists, the diagram arguments and additionally the last argument (method selection argument) are used.
-            Otherwise, the diagram arguments are used.
-
 * WithGiven special case: If the current entry belongs to a WithGiven operation or its without given pair, the with_given_without_given_name_pair is set.
                           Additionally, the with given flag of the WithGiven operation is set to true.
 
-* argument_list: If argument_list is not bound, it is set to include all arguments.
-
 * Redirect and post functions are created for all operations belonging to universal constructions (e.g. KernelLift) which are not a WithGiven operation.
 
 

CAP/gap/CategoryMorphisms.gd

@@ -1933,10 +1933,6 @@ DeclareOperation( "AddInterpretMorphismFromDistinguishedObjectToHomomorphismStru
 DeclareOperation( "AddInterpretMorphismFromDistinguishedObjectToHomomorphismStructureAsMorphism",
                   [ IsCapCategory, IsList ] );
 
-##
-DeclareOperation( "SolveLinearSystemInAbCategoryOp",
-                   [ IsList, IsList, IsList, IsCapCategory ] );
-
 #! @Description
 #! The arguments are three lists $\alpha$, $\beta$, and $\gamma$.
 #! The first list $\alpha$ (the left coefficients) is a list of list of morphisms $\alpha_{ij}: A_i \rightarrow B_j$,
@@ -1968,10 +1964,6 @@ DeclareOperation( "AddSolveLinearSystemInAbCategory",
 DeclareOperation( "AddSolveLinearSystemInAbCategory",
                   [ IsCapCategory, IsList ] );
 
-##
-DeclareOperation( "MereExistenceOfSolutionOfLinearSystemInAbCategoryOp",
-                   [ IsList, IsList, IsList, IsCapCategory ] );
-
 #! @Description
 #! Like <C>SolveLinearSystemInAbCategory</C>,
 #! but the output is simply <C>true</C> if a solution exists,

CAP/gap/CategoryMorphisms.gi

@@ -163,6 +163,12 @@ InstallMethod( AdditiveInverse,
 
 AdditiveInverseForMorphisms );
 
+##
+InstallOtherMethod( InverseImmutable,
+                  [ IsCapCategory, IsCapCategoryMorphism ],
+
+InverseOp );
+
 ##
 InstallMethod( \*,
                [ IsRingElement, IsCapCategoryMorphism ],
@@ -220,7 +226,14 @@ InstallMethod( IsEqualForCacheForMorphisms,
 
   IsEqualForCache );
 
+##
+# generic fallback to IsIdenticalObj
+InstallOtherMethod( IsEqualForCache,
+               [ IsCapCategory, IsCapCategoryMorphism, IsCapCategoryMorphism ],
+
+  { cat, mor1, mor2 } -> IsIdenticalObj( mor1, mor2 ) );
 
+##
 InstallMethod( AddMorphismRepresentation,
                [ IsCapCategory, IsObject ],
 
@@ -512,26 +525,6 @@ InstallMethod( HomomorphismStructureOnMorphisms,
 
 end );
 
-##
-InstallMethod( SolveLinearSystemInAbCategory,
-               [ IsList, IsList, IsList ],
-
-  function( left_coeffs, right_coeffs, right_side )
-
-    return SolveLinearSystemInAbCategoryOp( left_coeffs, right_coeffs, right_side, CapCategory( right_side[1] ) );
-
-end );
-
-##
-InstallMethod( MereExistenceOfSolutionOfLinearSystemInAbCategory,
-               [ IsList, IsList, IsList ],
-
-  function( left_coeffs, right_coeffs, right_side )
-
-    return MereExistenceOfSolutionOfLinearSystemInAbCategoryOp( left_coeffs, right_coeffs, right_side, CapCategory( right_side[1] ) );
-
-end );
-
 ##
 InstallMethod( HomStructure,
                [ IsCapCategoryMorphism, IsCapCategoryMorphism ],

CAP/gap/CategoryObjects.gi

@@ -209,6 +209,14 @@ InstallMethod( IsEqualForCacheForObjects,
 
   IsEqualForCache );
 
+##
+# generic fallback to IsIdenticalObj
+InstallOtherMethod( IsEqualForCache,
+               [ IsCapCategory, IsCapCategoryObject, IsCapCategoryObject ],
+
+  { cat, obj1, obj2 } -> IsIdenticalObj( obj1, obj2 ) );
+
+##
 InstallMethod( AddObjectRepresentation,
                [ IsCapCategory, IsObject ],
 

CAP/gap/Derivations.gi

@@ -219,7 +219,41 @@ end );
 InstallMethod( AddDerivation,
                [ IsDerivedMethodGraphRep, IsDerivedMethod ],
 function( G, d )
-  local op_name;
+  local method_name, filter_list, number_of_proposed_arguments, current_function_argument_number, impl, op_name;
+
+  if IsIdenticalObj( G, CAP_INTERNAL_DERIVATION_GRAPH ) then
+
+    method_name := TargetOperation( d );
+
+    if not method_name in RecNames( CAP_INTERNAL_METHOD_NAME_RECORD ) then
+
+        Error( "trying to add a derivation to CAP_INTERNAL_DERIVATION_GRAPH for a method not in CAP_INTERNAL_METHOD_NAME_RECORD" );
+
+    fi;
+
+    filter_list := CAP_INTERNAL_METHOD_NAME_RECORD!.(method_name).filter_list;
+
+    number_of_proposed_arguments := Length( filter_list );
+
+    for impl in DerivationFunctionsWithExtraFilters( d ) do
+
+        current_function_argument_number := NumberArgumentsFunction( impl[ 1 ] );
+
+        if current_function_argument_number >= 0 and current_function_argument_number <> number_of_proposed_arguments then
+            Error( "While adding a derivation for ", method_name, ": given function has ", String( current_function_argument_number ),
+                   " arguments but should have ", String( number_of_proposed_arguments ) );
+        fi;
+
+    od;
+
+    if NumberArgumentsFunction( CategoryFilter( d ) ) = 0 or NumberArgumentsFunction( CategoryFilter( d ) ) > 1 then
+
+        Error( "the CategoryFilter of a derivation must accept exactly one argument" );
+
+    fi;
+
+  fi;
+
   Add( G!.derivations_by_target.( TargetOperation( d ) ), d );
   for op_name in UsedOperations( d ) do
     Add( G!.derivations_by_used_ops.( op_name ), d );