|
ActiveTcl User Guide |
|
- NAME
- Tcl_LinkVar, Tcl_UnlinkVar, Tcl_UpdateLinkedVar - link Tcl
variable to C variable
- SYNOPSIS
- ARGUMENTS
- DESCRIPTION
- TCL_LINK_INT
- TCL_LINK_UINT
- TCL_LINK_CHAR
- TCL_LINK_UCHAR
- TCL_LINK_SHORT
- TCL_LINK_USHORT
- TCL_LINK_LONG
- TCL_LINK_ULONG
- TCL_LINK_DOUBLE
- TCL_LINK_FLOAT
- TCL_LINK_WIDE_INT
- TCL_LINK_WIDE_UINT
- TCL_LINK_BOOLEAN
- TCL_LINK_STRING
- KEYWORDS
Tcl_LinkVar, Tcl_UnlinkVar, Tcl_UpdateLinkedVar - link Tcl variable
to C variable
#include <tcl.h>
int
Tcl_LinkVar(interp, varName, addr, type)
Tcl_UnlinkVar(interp, varName)
Tcl_UpdateLinkedVar(interp, varName)
- Tcl_Interp *interp
(in)
- Interpreter that contains varName. Also used by
Tcl_LinkVar to return error messages.
- const char *varName (in)
- Name of global variable.
- char *addr (in)
- Address of C variable that is to be linked to
varName.
- int type (in)
- Type of C variable. Must be one of TCL_LINK_INT,
TCL_LINK_UINT, TCL_LINK_CHAR, TCL_LINK_UCHAR,
TCL_LINK_SHORT, TCL_LINK_USHORT,
TCL_LINK_LONG, TCL_LINK_ULONG,
TCL_LINK_WIDE_INT, TCL_LINK_WIDE_UINT,
TCL_LINK_FLOAT, TCL_LINK_DOUBLE,
TCL_LINK_BOOLEAN, or TCL_LINK_STRING, optionally
OR'ed with TCL_LINK_READ_ONLY to make Tcl variable
read-only.
Tcl_LinkVar uses variable traces to keep the Tcl variable
named by varName in sync with the C variable at the address
given by addr. Whenever the Tcl variable is read the value
of the C variable will be returned, and whenever the Tcl variable
is written the C variable will be updated to have the same value.
Tcl_LinkVar normally returns TCL_OK; if an error
occurs while setting up the link (e.g. because varName is
the name of array) then TCL_ERROR is returned and the
interpreter's result contains an error message.
The type argument specifies the type of the C variable,
and must have one of the following values, optionally OR'ed with
TCL_LINK_READ_ONLY:
- TCL_LINK_INT
- The C variable is of type int. Any value written into
the Tcl variable must have a proper integer form acceptable to
Tcl_GetIntFromObj;
attempts to write non-integer values into varName will be
rejected with Tcl errors.
- TCL_LINK_UINT
- The C variable is of type unsigned int. Any value
written into the Tcl variable must have a proper unsigned integer
form acceptable to Tcl_GetWideIntFromObj and in the
platform's defined range for the unsigned int type; attempts
to write non-integer values (or values outside the range) into
varName will be rejected with Tcl errors.
- TCL_LINK_CHAR
- The C variable is of type char. Any value written into
the Tcl variable must have a proper integer form acceptable to
Tcl_GetIntFromObj and be
in the range of the char datatype; attempts to write
non-integer or out-of-range values into varName will be
rejected with Tcl errors.
- TCL_LINK_UCHAR
- The C variable is of type unsigned char. Any value
written into the Tcl variable must have a proper unsigned integer
form acceptable to Tcl_GetIntFromObj and in the
platform's defined range for the unsigned char type;
attempts to write non-integer values (or values outside the range)
into varName will be rejected with Tcl errors.
- TCL_LINK_SHORT
- The C variable is of type short. Any value written into
the Tcl variable must have a proper integer form acceptable to
Tcl_GetIntFromObj and be
in the range of the short datatype; attempts to write
non-integer or out-of-range values into varName will be
rejected with Tcl errors.
- TCL_LINK_USHORT
- The C variable is of type unsigned short. Any value
written into the Tcl variable must have a proper unsigned integer
form acceptable to Tcl_GetIntFromObj and in the
platform's defined range for the unsigned short type;
attempts to write non-integer values (or values outside the range)
into varName will be rejected with Tcl errors.
- TCL_LINK_LONG
- The C variable is of type long. Any value written into
the Tcl variable must have a proper integer form acceptable to
Tcl_GetLongFromObj;
attempts to write non-integer or out-of-range values into
varName will be rejected with Tcl errors.
- TCL_LINK_ULONG
- The C variable is of type unsigned long. Any value
written into the Tcl variable must have a proper unsigned integer
form acceptable to Tcl_GetWideIntFromObj and in the
platform's defined range for the unsigned long type;
attempts to write non-integer values (or values outside the range)
into varName will be rejected with Tcl errors.
- TCL_LINK_DOUBLE
- The C variable is of type double. Any value written into
the Tcl variable must have a proper real form acceptable to Tcl_GetDoubleFromObj;
attempts to write non-real values into varName will be
rejected with Tcl errors.
- TCL_LINK_FLOAT
- The C variable is of type float. Any value written into
the Tcl variable must have a proper real form acceptable to Tcl_GetDoubleFromObj and
must be within the range acceptable for a float; attempts to
write non-real values (or values outside the range) into
varName will be rejected with Tcl errors.
- TCL_LINK_WIDE_INT
- The C variable is of type Tcl_WideInt (which is an
integer type at least 64-bits wide on all platforms that can
support it.) Any value written into the Tcl variable must have a
proper integer form acceptable to Tcl_GetWideIntFromObj; attempts to
write non-integer values into varName will be rejected with
Tcl errors.
- TCL_LINK_WIDE_UINT
- The C variable is of type Tcl_WideUInt (which is an
unsigned integer type at least 64-bits wide on all platforms that
can support it.) Any value written into the Tcl variable must have
a proper unsigned integer form acceptable to Tcl_GetWideIntFromObj (it will be
cast to unsigned); attempts to write non-integer values into
varName will be rejected with Tcl errors.
- TCL_LINK_BOOLEAN
- The C variable is of type int. If its value is zero then
it will read from Tcl as “0”; otherwise it will read
from Tcl as “1”. Whenever varName is modified,
the C variable will be set to a 0 or 1 value. Any value written
into the Tcl variable must have a proper boolean form acceptable to
Tcl_GetBooleanFromObj;
attempts to write non-boolean values into varName will be
rejected with Tcl errors.
- TCL_LINK_STRING
- The C variable is of type char *. If its value is not
NULL then it must be a pointer to a string allocated with Tcl_Alloc or ckalloc. Whenever the Tcl variable is
modified the current C string will be freed and new memory will be
allocated to hold a copy of the variable's new value. If the C
variable contains a NULL pointer then the Tcl variable will read as
“NULL”.
If the TCL_LINK_READ_ONLY flag is present in type
then the variable will be read-only from Tcl, so that its value can
only be changed by modifying the C variable. Attempts to write the
variable from Tcl will be rejected with errors.
Tcl_UnlinkVar removes the link previously set up for the
variable given by varName. If there does not exist a link
for varName then the procedure has no effect.
Tcl_UpdateLinkedVar may be invoked after the C variable
has changed to force the Tcl variable to be updated immediately. In
many cases this procedure is not needed, since any attempt to read
the Tcl variable will return the latest value of the C variable.
However, if a trace has been set on the Tcl variable (such as a Tk
widget that wishes to display the value of the variable), the trace
will not trigger when the C variable has changed.
Tcl_UpdateLinkedVar ensures that any traces on the Tcl
variable are invoked.
boolean, integer, link, read-only, real, string, traces, variable
Copyright © 1995-1997 Roger E. Critchlow Jr.
Copyright © 1993 The Regents of the University of California.
Copyright © 1994-1996 Sun Microsystems, Inc.