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#############################################################################
##
## This file is part of GAP, a system for computational discrete algebra.
## This file's authors include Steve Linton.
##
## Copyright of GAP belongs to its developers, whose names are too numerous
## to list here. Please refer to the COPYRIGHT file for details.
##
## SPDX-License-Identifier: GPL-2.0-or-later
##
##
## This file contains the second stage of the "public" interface to
## the global variable namespace, allowing globals to be accessed and
## set by name.
##
## This is defined in two stages. global.g defines "capitalized" versions
## of the functions which do not use Info or other niceties and are not
## set up with InstallGlobalFunction. This can thus be read early, and
## the functions it defines can be used to define functions used to read
## more of the library.
##
## This file and global.gd install the really "public"
## functions and can be read later (once Info, DeclareGlobalFunction,
## etc are there)
##
## All of these functions give a warning at level 2 if the global
## variable name contains characters not recognised as part of
## identifiers by the GAP parser
##
## Functions that read data give Info messages at level 3 for InfoGlobal
## Functions that change data give Info messages at level 2 for InfoGlobal
##
#############################################################################
##
#I InfoGlobal . . . . . . . . . . . . . . . . . . information message class
##
DeclareInfoClass("InfoGlobal");
#############################################################################
##
#F IsValidIdentifier( <str> ) . . . check if a string is a valid identifier
##
InstallGlobalFunction( IsValidIdentifier, function(str)
return ForAll(str, c -> c in IdentifierLetters) and
ForAny(str, c -> not (c in "0123456789")) and
not str in GAPInfo.Keywords;
end);
#############################################################################
##
#F CheckGlobalName( <name> ) . . . check global variable name -- warn if odd
##
##
CheckGlobalName := function( name )
if not IsString( name ) then
Error("CheckGlobalName: the argument must be a string");
fi;
if ForAny(name, l -> not l in IdentifierLetters) then
Info(InfoWarning + InfoGlobal, 2,
"suspicious global variable name ", name);
fi;
end;
#############################################################################
##
#M ValueGlobal ( <name> ) . . . . . . . . . . . access a global by its name
##
## ValueGlobal ( <name> ) returns the value currently bound to the global
## variable named by the string <name>. An error is raised if no value
## is currently bound
##
InstallGlobalFunction( ValueGlobal, VALUE_GLOBAL );
#############################################################################
##
#M IsBoundGlobal ( <name> ) . . . . check if a global is bound by its name
##
## IsBoundGlobal ( <name> ) returns true if a value currently bound
## to the global variable named by the string <name> and false otherwise
##
InstallGlobalFunction( IsBoundGlobal,
function (name)
local isbound;
CheckGlobalName( name );
isbound := ISBOUND_GLOBAL(name);
Info( InfoGlobal, 3,
"IsBoundGlobal: called for ", name, " returned ", isbound);
return isbound;
end);
#############################################################################
##
#M IsAutoGlobal ( <name> ) . . . . check if a global is automatic
##
InstallGlobalFunction( IsAutoGlobal,
function (name)
local isauto;
CheckGlobalName( name );
isauto := IS_AUTO_GVAR(name);
Info( InfoGlobal, 3,
"IsAutoGlobal: called for ", name, " returned ", isauto);
return isauto;
end);
#############################################################################
##
#M UnbindGlobal ( <name> ) . . . . . . . . . . unbind a global by its name
##
## UnbindGlobal ( <name> ) removes any value currently bound
## to the global variable named by the string <name>. Nothing is returned
##
## A warning is given isf <name> was not bound
## The global variable named by <name> must be writable,
## otherwise an error is raised.
##
InstallGlobalFunction( UnbindGlobal,
function (name)
CheckGlobalName( name );
if not ISBOUND_GLOBAL( name ) then
Info( InfoWarning + InfoGlobal, 1,
"UnbindGlobal: ", name, " already unbound");
fi;
Info( InfoGlobal, 2, "UnbindGlobal: called for ", name);
UNBIND_GLOBAL( name );
end);
#############################################################################
##
#F IsReadOnlyGlobal ( <name> ) . determine if a global variable is read-only
##
## IsReadOnlyGlobal ( <name> ) returns true if the global variable
## named by the string <name> is read-only and false otherwise (the default)
##
InstallGlobalFunction( IsReadOnlyGlobal,
function (name)
local isro;
CheckGlobalName( name );
isro := IS_READ_ONLY_GLOBAL(name);
Info( InfoGlobal, 3,
"IsReadOnlyGlobal: called for ", name, " returned ", isro);
return isro;
end);
#############################################################################
##
#F IsConstantGlobal ( <name> ) . determine if a global variable is constant
##
## IsConstantGlobal ( <name> ) returns true if the global variable
## named by the string <name> is constant and false otherwise (the default)
##
InstallGlobalFunction( IsConstantGlobal,
function (name)
local isro;
CheckGlobalName( name );
isro := IS_CONSTANT_GLOBAL(name);
Info( InfoGlobal, 3,
"IsConstantGlobal: called for ", name, " returned ", isro);
return isro;
end);
#############################################################################
##
#F MakeReadOnlyGlobal ( <name> ) . . . . . make a global variable read-only
##
## MakeReadOnlyGlobal ( <name> ) marks the global variable named by the
## string <name> as read-only.
##
## A warning is given if <name> has no value bound to it or if it is
## already read-only
##
InstallGlobalFunction( MakeReadOnlyGlobal,
function (name)
CheckGlobalName( name );
if name in ["time", "last", "last2", "last3", "~"] then
Error("Making ",name," read-only is not a good idea!");
fi;
if not ISBOUND_GLOBAL( name ) then
Info( InfoWarning + InfoGlobal, 1,
"MakeReadOnlyGlobal: ", name, " no value bound");
fi;
if IS_READ_ONLY_GLOBAL( name ) then
Info( InfoWarning + InfoGlobal, 1,
"MakeReadOnlyGlobal: ", name, " already read-only");
fi;
Info( InfoGlobal, 2, "MakeReadOnlyGlobal: called for ", name);
MAKE_READ_ONLY_GLOBAL( name );
end);
#############################################################################
##
#F MakeReadWriteGlobal ( <name> ) . . . . make a global variable read-write
##
## MakeReadWriteGlobal ( <name> ) marks the global variable named by the
## string <name> as read-write
##
## A warning is given if <name> is already read-write
##
InstallGlobalFunction( MakeReadWriteGlobal,
function (name)
CheckGlobalName( name );
if not IS_READ_ONLY_GLOBAL( name ) then
Info( InfoWarning + InfoGlobal, 1,
"MakeReadWriteGlobal: ", name, " already read-write");
fi;
Info( InfoGlobal, 2, "MakeReadWriteGlobal: called for ", name);
MAKE_READ_WRITE_GLOBAL( name );
end);
#############################################################################
##
#F MakeConstantGlobal ( <name> ) . . . . . make a global variable constant
##
## MakeConstantGlobal ( <name> ) marks the global variable named by the
## string <name> as constant
##
## A warning is given if <name> is already constant
##
InstallGlobalFunction( MakeConstantGlobal,
function (name)
CheckGlobalName( name );
if IS_CONSTANT_GLOBAL( name ) then
Info( InfoWarning + InfoGlobal, 1,
"MakeConstantGlobal: ", name, " already constant");
fi;
Info( InfoGlobal, 2, "MakeConstantGlobal: called for ", name);
MAKE_CONSTANT_GLOBAL( name );
end);
#############################################################################
##
#F BindGlobal ( <name>, <val> ) . . . . . . sets a global variable 'safely'
##
## BindGlobal ( <name>, <val> ) sets the global variable named by
## the string <name> to the value <val>, provided it was previously
## unbound, and makes it read-only. This is intended to be the normal
## way to create and set "official" global variable (such as
## Operations and Categories)
##
## An error is given if <name> already had a value bound.
##
InstallGlobalFunction( BindGlobal,
function (name, value)
CheckGlobalName( name );
Info( InfoGlobal, 2, "BindGlobal: called to set ", name, " to ", value);
BIND_GLOBAL( name, value );
end);
InstallGlobalFunction( BindConstant,
function (name, value)
CheckGlobalName( name );
Info( InfoGlobal, 2, "BindConstant: called to set ", name, " to ", value);
BIND_CONSTANT( name, value );
end);
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