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#############################################################################
##
#W function.g GAP library Thomas Breuer
#W & Frank Celler
##
#H @(#)$Id: function.g,v 4.14 2002/04/15 10:04:40 sal Exp $
##
#Y Copyright (C) 1997, Lehrstuhl D fuer Mathematik, RWTH Aachen, Germany
#Y (C) 1998 School Math and Comp. Sci., University of St. Andrews, Scotland
#Y Copyright (C) 2002 The GAP Group
##
## This file deals with functions.
##
Revision.function_g :=
"@(#)$Id: function.g,v 4.14 2002/04/15 10:04:40 sal Exp $";
#############################################################################
##
#C IsFunction( <obj> ) . . . . . . . . . . . . . . . . category of functions
##
## is the category of functions.
DeclareCategoryKernel( "IsFunction",
IS_OBJECT,
IS_FUNCTION );
#############################################################################
##
#C IsOperation( <obj> ) . . . . . . . . . . . . . . category of operations
##
## is the category of operations. Every operation is a function, but not
## vice versa.
DeclareCategoryKernel( "IsOperation",
IS_FUNCTION,
IS_OPERATION );
#############################################################################
##
#V FunctionsFamily . . . . . . . . . . . . . . . . . . . family of functions
##
## is the family of all functions.
BIND_GLOBAL( "FunctionsFamily", NewFamily( "FunctionsFamily", IsFunction ) );
#############################################################################
##
#V TYPE_FUNCTION . . . . . . . . . . . . . . . . . . . . type of a function
##
BIND_GLOBAL( "TYPE_FUNCTION", NewType( FunctionsFamily,
IsFunction and IsInternalRep ) );
#############################################################################
##
#F TYPE_OPERATION . . . . . . . . . . . . . . . . . . . type of a operation
##
BIND_GLOBAL( "TYPE_OPERATION",
NewType( FunctionsFamily,
IsFunction and IsOperation and IsInternalRep ) );
#############################################################################
##
#F NameFunction( <func> ) . . . . . . . . . . . . . . . name of a function
##
## returns the name of a function. For operations, this is the name used in
## their declaration. For functions, this is the variable name they were
## first assigned to. (For some internal functions, this might be a name
## *different* from the name that is documented.)
## If no such name exists, `"unknown"' is returned.
#T If objects simulate functions this must become an operation.
##
BIND_GLOBAL( "NameFunction", NAME_FUNC );
#############################################################################
##
#F NumberArgumentsFunction( <func> )
##
## returns the number of arguments the function <func> accepts. For
## functions that use `arg' to take a variable number of arguments, as well
## as for operations, -1 is returned. For attributes, 1 is returned.
BIND_GLOBAL( "NumberArgumentsFunction", NARG_FUNC );
#############################################################################
##
#F CallFuncList( <func>, <args> ) . . . . . . . . . . . . . call a function
##
## returns the result, when calling function <func> with the arguments
## given in the list <args>, i.e.~<args> is ``unwrapped'' so that <args>
## appears as several arguments to <func>.
#T If objects simulate functions this must become an operation.
##
UNBIND_GLOBAL("CallFuncList"); # was declared 2b defined
BIND_GLOBAL( "CallFuncList", CALL_FUNC_LIST );
#############################################################################
##
#F ReturnTrue( ... ) . . . . . . . . . . . . . . . . . . . . . . always true
##
## This function takes any number of arguments, and always returns `true'.
BIND_GLOBAL( "ReturnTrue", RETURN_TRUE );
#############################################################################
##
#F ReturnFalse( ... ) . . . . . . . . . . . . . . . . . . . . always false
##
## This function takes any number of arguments, and always returns `false'.
BIND_GLOBAL( "ReturnFalse", RETURN_FALSE );
#############################################################################
##
#F ReturnFail( ... ) . . . . . . . . . . . . . . . . . . . . . . always fail
##
## This function takes any number of arguments, and always returns `fail'.
BIND_GLOBAL( "ReturnFail", RETURN_FAIL );
#############################################################################
##
#F IdFunc( <obj> ) . . . . . . . . . . . . . . . . . . . . . . return <obj>
##
## returns <obj>.
BIND_GLOBAL( "IdFunc", ID_FUNC );
#############################################################################
##
#M ViewObj( <func> ) . . . . . . . . . . . . . . . . . . . . . . view method
##
InstallMethod( ViewObj, "for a function", true, [IsFunction], 0,
function ( func )
local nams, narg, i;
Print("function( ");
nams := NAMS_FUNC(func);
narg := NARG_FUNC(func);
if nams = fail then
Print( "<",narg," unnamed arguments>" );
elif narg = -1 then
Print("arg");
elif narg > 0 then
Print(nams[1]);
for i in [2..narg] do
Print(", ",nams[i]);
od;
fi;
Print(" ) ... end");
end);
BIND_GLOBAL( "PRINT_OPERATION", function ( op )
Print("<Operation \"",NAME_FUNC(op),"\">");
end);
InstallMethod( ViewObj, "for an operation", true, [IsOperation], 0,
PRINT_OPERATION);
#############################################################################
##
#E function.g . . . . . . . . . . . . . . . . . . . . . . . . . . ends here
##
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