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#############################################################################
##
#W methsel2.g GAP library Steve Linton
## Hans Ulrich Besche
## Max Neuenhoeffer
##
#H @(#)$Id: methsel2.g,v 4.12 2002/04/15 10:05:03 sal Exp $
##
#Y Copyright (C) 1996, 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 defines some functions associated with method selection,
## which do not need to be compiled by default. More performance critical
## functions are found in methsel1.g
##
Revision.methsel2_g :=
"@(#)$Id: methsel2.g,v 4.12 2002/04/15 10:05:03 sal Exp $";
## This is a dirty hack, because this function is defined only later:
ApplicableMethod := fail;
## See below for the other part of it!
#############################################################################
##
#F HANDLE_METHOD_NOT_FOUND( <information> ) . . . raise the method not
## found error
##
## <information> is a plain record passed by the kernel when no
## method is found. Components so far defined are:
##
## .Operation -- the operation called
## .Arguments -- the arguments as a plain (immutable) list
## .isVerbose -- if the operation was being traced
## .isConstructor -- if the operation is a constructor
## .Precedence -- the "precedence" of the method sought 0 for
## first choice, 1 after one TryNextMethod(), etc.
##
HANDLE_METHOD_NOT_FOUND := function ( INF )
local no_method_found, ShowArguments, ShowArgument, ShowDetails, ShowMethods,
ShowOtherMethods;
#############################################################################
##
#F ShowArguments( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . .
##
## This function is only available within a break loop caused by a ``No
## Method Found''-error. It prints as a list the arguments of the operation
## call for which no method was found.
## %% `ShowArguments' can
## %% be called with any number of arguments. They are ignored.
##
ShowArguments := function( arg )
Print( INF.Arguments, "\n" );
end;
#############################################################################
##
#F ShowArgument(<nr>) . . . . . . . . . . . . . . . . . . . . . . . . . . .
##
## This function is only available within a break loop caused by a ``No
## Method Found''-error. It prints the <nr>-th arguments of the operation call
## for which no method was found. `ShowArgument' needs exactly one
## argument which is an integer between 0 and the number of arguments the
## operation was called with.
##
ShowArgument := function( arg )
if LENGTH(arg) <> 1 or not IS_INT(arg[1]) or arg[1] <= 0
or arg[1] > LENGTH(INF.Arguments) then
Print( "Usage: `ShowArgument( <nr> )' where <nr> is an integer between ",
1," and ",LENGTH(INF.Arguments),"\n");
else
Print( INF.Arguments[arg[1]], "\n" );
fi;
end;
#############################################################################
##
#F ShowDetails( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
##
## This function is only available within a break loop caused by a ``No
## Method Found''-error. It prints the details of this error: The
## operation, the number of arguments, a flag which indicates whether the
## operation is being traced, a flag which indicates whether the
## operation is a constructor method, and the number of methods that
## refused to apply by calling `TryNextMethod'. The last number is called
## `Choice' and is printed as an ordinal. So if exactly $k$ methods were
## found but called `TryNextMethod' and there were no more methods it says
## `Choice: $k$th'.
## %% `ShowDetails' can be called with any number of
## %% arguments. They are ignored.
##
ShowDetails := function( arg )
Print( "--------------------------------------------\n");
Print( "Information about a `No method found'-error:\n");
Print( "--------------------------------------------\n");
Print( "Operation : ", NAME_FUNC( INF.Operation ), "\n" );
Print( "Number of Arguments : ", LENGTH( INF.Arguments ), "\n" );
Print( "Operation traced : ", INF.isVerbose, "\n" );
Print( "IsConstructor : ", INF.isConstructor, "\n" );
Print( "Choice : ", Ordinal(INF.Precedence+1), "\n" );
end;
#############################################################################
##
#F ShowMethods( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
#F ShowMethods( <verbosity> ) . . . . . . . . . . . . . . . . . . . . . . .
##
## This function is only available within a break loop caused by a ``No
## Method Found''-error. It prints an overview about the installed methods
## for those arguments the operation was called with (using
## `ApplicableMethod', see "ApplicableMethod"). The verbosity can be
## controlled by the optional integer parameter <verbosity>. The default
## is 2, which lists all applicable methods. With verbosity 1
## `ShowMethods' only shows the number of installed methods and the
## methods matching, which can only be those that were already called but
## refused to work by calling `TryNextMethod'. With verbosity 3 not only
## all installed methods but also the reasons why they do not match are
## displayed.
##
ShowMethods := function( arg )
local verbosity;
if LENGTH(arg) <> 1 or not IS_INT(arg[1]) then
verbosity := 2;
elif arg[1] < 1 then
verbosity := 1;
else
verbosity := arg[1];
fi;
ApplicableMethod( INF.Operation, INF.Arguments, verbosity, "all" );
end;
#############################################################################
##
#F ShowOtherMethods( ) . . . . . . . . . . . . . . . . . . . . . . . . . . .
#F ShowOtherMethods( <verbosity> ) . . . . . . . . . . . . . . . . . . . . .
##
## This function is only available within a break loop caused by a ``No
## Method Found''-error. It prints an overview about the installed methods
## for a different number of arguments than the number of arguments the
## operation was called with (using `ApplicableMethod', see
## "ApplicableMethod"). The verbosity can be controlled by the optional
## integer parameter <verbosity>. The default is 1 which lists only the
## number of applicable methods. With verbosity 2 `ShowOtherMethods' lists
## all installed methods and with verbosity 3 also the reasons, why they
## are not applicable. Calling `ShowOtherMethods' with verbosity 3 in this
## function will normally not make any sense, because the different
## numbers of arguments are simulated by supplying the corresponding
## number of ones, for which normally no reasonable methods will be
## installed.
##
ShowOtherMethods := function( arg )
local verbosity, i, l, args;
if LENGTH(arg) <> 1 or not IS_INT(arg[1]) then
verbosity := 1;
elif arg[1] < 1 then
verbosity := 1;
else
verbosity := arg[1];
fi;
l := [0..6];
args := [];
for i in l do
if i <> LENGTH( INF.Arguments ) then
ApplicableMethod( INF.Operation, args, verbosity, "all" );
Print( "\n" );
fi;
ADD_LIST(args,1);
od;
end;
# Remember, we are in the function `HANDLE_METHOD_NOT_FOUND'!
Print( "Error, no method found! For debugging hints type ?Recovery from NoMethodFound\n" );
no_method_found:="no ";
APPEND_LIST(no_method_found,Ordinal(INF.Precedence+1));
APPEND_LIST(no_method_found," choice method found for `");
APPEND_LIST(no_method_found,NAME_FUNC(INF.Operation));
APPEND_LIST(no_method_found,"' on ");
APPEND_LIST(no_method_found,STRING_INT(LENGTH(INF.Arguments)));
APPEND_LIST(no_method_found," arguments");
Error(no_method_found);
end;
## This is the other part of the above mentioned dirty trick:
Unbind( ApplicableMethod );
#############################################################################
##
#F NONAVAILABLE_SHOW_FUNC ( ) . . . . . . . . . . . . . . . . . . . . . . .
##
## This is an excuse if the user tries to call the `Show...' functions
## without a NoMethodFound-error.
##
BIND_GLOBAL( "NONAVAILABLE_SHOW_FUNC", function( arg )
Error( "this function is only available after a 'no method found'-Error" );
end );
# The following comes in handy also for command line completion:
BIND_GLOBAL( "ShowArguments", NONAVAILABLE_SHOW_FUNC );
BIND_GLOBAL( "ShowArgument", NONAVAILABLE_SHOW_FUNC );
BIND_GLOBAL( "ShowDetails", NONAVAILABLE_SHOW_FUNC );
BIND_GLOBAL( "ShowMethods", NONAVAILABLE_SHOW_FUNC );
BIND_GLOBAL( "ShowOtherMethods", NONAVAILABLE_SHOW_FUNC );
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