--- /dev/null
+'\"
+'\" Copyright (c) 1993 The Regents of the University of California.
+'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
+'\"
+'\" See the file "license.terms" for information on usage and redistribution
+'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+'\"
+.TH Tcl_LinkVar 3 7.5 Tcl "Tcl Library Procedures"
+.so man.macros
+.BS
+.SH NAME
+Tcl_LinkVar, Tcl_UnlinkVar, Tcl_UpdateLinkedVar \- link Tcl variable to C variable
+.SH SYNOPSIS
+.nf
+\fB#include <tcl.h>\fR
+.sp
+int
+\fBTcl_LinkVar\fR(\fIinterp, varName, addr, type\fR)
+.sp
+\fBTcl_UnlinkVar\fR(\fIinterp, varName\fR)
+.sp
+\fBTcl_UpdateLinkedVar\fR(\fIinterp, varName\fR)
+.SH ARGUMENTS
+.AS Tcl_Interp writable
+.AP Tcl_Interp *interp in
+Interpreter that contains \fIvarName\fR.
+Also used by \fBTcl_LinkVar\fR to return error messages.
+.AP "const char" *varName in
+Name of global variable.
+.AP char *addr in
+Address of C variable that is to be linked to \fIvarName\fR.
+.AP int type in
+Type of C variable. Must be one of \fBTCL_LINK_INT\fR,
+\fBTCL_LINK_UINT\fR, \fBTCL_LINK_CHAR\fR, \fBTCL_LINK_UCHAR\fR,
+\fBTCL_LINK_SHORT\fR, \fBTCL_LINK_USHORT\fR, \fBTCL_LINK_LONG\fR,
+\fBTCL_LINK_ULONG\fR, \fBTCL_LINK_WIDE_INT\fR,
+\fBTCL_LINK_WIDE_UINT\fR, \fBTCL_LINK_FLOAT\fR,
+\fBTCL_LINK_DOUBLE\fR, \fBTCL_LINK_BOOLEAN\fR, or
+\fBTCL_LINK_STRING\fR, optionally OR'ed with \fBTCL_LINK_READ_ONLY\fR
+to make Tcl variable read-only.
+.BE
+.SH DESCRIPTION
+.PP
+\fBTcl_LinkVar\fR uses variable traces to keep the Tcl variable
+named by \fIvarName\fR in sync with the C variable at the address
+given by \fIaddr\fR.
+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.
+\fBTcl_LinkVar\fR normally returns \fBTCL_OK\fR; if an error occurs
+while setting up the link (e.g. because \fIvarName\fR is the
+name of array) then \fBTCL_ERROR\fR is returned and the interpreter's result
+contains an error message.
+.PP
+The \fItype\fR argument specifies the type of the C variable,
+and must have one of the following values, optionally OR'ed with
+\fBTCL_LINK_READ_ONLY\fR:
+.TP
+\fBTCL_LINK_INT\fR
+The C variable is of type \fBint\fR.
+Any value written into the Tcl variable must have a proper integer
+form acceptable to \fBTcl_GetIntFromObj\fR; attempts to write
+non-integer values into \fIvarName\fR will be rejected with
+Tcl errors. Incomplete integer representations (like the empty
+string, '+', '-' or the hex/octal/binary prefix) are accepted
+as if they are valid too.
+.TP
+\fBTCL_LINK_UINT\fR
+The C variable is of type \fBunsigned int\fR.
+Any value written into the Tcl variable must have a proper unsigned
+integer form acceptable to \fBTcl_GetWideIntFromObj\fR and in the
+platform's defined range for the \fBunsigned int\fR type; attempts to
+write non-integer values (or values outside the range) into
+\fIvarName\fR will be rejected with Tcl errors. Incomplete integer
+representations (like the empty string, '+', '-' or the hex/octal/binary
+prefix) are accepted as if they are valid too.
+.TP
+\fBTCL_LINK_CHAR\fR
+The C variable is of type \fBchar\fR.
+Any value written into the Tcl variable must have a proper integer
+form acceptable to \fBTcl_GetIntFromObj\fR and be in the range of the
+\fBchar\fR datatype; attempts to write non-integer or out-of-range
+values into \fIvarName\fR will be rejected with Tcl errors. Incomplete
+integer representations (like the empty string, '+', '-' or the
+hex/octal/binary prefix) are accepted as if they are valid too.
+.TP
+\fBTCL_LINK_UCHAR\fR
+The C variable is of type \fBunsigned char\fR.
+Any value written into the Tcl variable must have a proper unsigned
+integer form acceptable to \fBTcl_GetIntFromObj\fR and in the
+platform's defined range for the \fBunsigned char\fR type; attempts to
+write non-integer values (or values outside the range) into
+\fIvarName\fR will be rejected with Tcl errors. Incomplete integer
+representations (like the empty string, '+', '-' or the hex/octal/binary
+prefix) are accepted as if they are valid too.
+.TP
+\fBTCL_LINK_SHORT\fR
+The C variable is of type \fBshort\fR.
+Any value written into the Tcl variable must have a proper integer
+form acceptable to \fBTcl_GetIntFromObj\fR and be in the range of the
+\fBshort\fR datatype; attempts to write non-integer or out-of-range
+values into \fIvarName\fR will be rejected with Tcl errors. Incomplete
+integer representations (like the empty string, '+', '-' or the
+hex/octal/binary prefix) are accepted as if they are valid too.
+.TP
+\fBTCL_LINK_USHORT\fR
+The C variable is of type \fBunsigned short\fR.
+Any value written into the Tcl variable must have a proper unsigned
+integer form acceptable to \fBTcl_GetIntFromObj\fR and in the
+platform's defined range for the \fBunsigned short\fR type; attempts to
+write non-integer values (or values outside the range) into
+\fIvarName\fR will be rejected with Tcl errors. Incomplete integer
+representations (like the empty string, '+', '-' or the hex/octal/binary
+prefix) are accepted as if they are valid too.
+.TP
+\fBTCL_LINK_LONG\fR
+The C variable is of type \fBlong\fR.
+Any value written into the Tcl variable must have a proper integer
+form acceptable to \fBTcl_GetLongFromObj\fR; attempts to write
+non-integer or out-of-range
+values into \fIvarName\fR will be rejected with Tcl errors. Incomplete
+integer representations (like the empty string, '+', '-' or the
+hex/octal/binary prefix) are accepted as if they are valid too.
+.TP
+\fBTCL_LINK_ULONG\fR
+The C variable is of type \fBunsigned long\fR.
+Any value written into the Tcl variable must have a proper unsigned
+integer form acceptable to \fBTcl_GetWideIntFromObj\fR and in the
+platform's defined range for the \fBunsigned long\fR type; attempts to
+write non-integer values (or values outside the range) into
+\fIvarName\fR will be rejected with Tcl errors. Incomplete integer
+representations (like the empty string, '+', '-' or the hex/octal/binary
+prefix) are accepted as if they are valid too.
+.TP
+\fBTCL_LINK_DOUBLE\fR
+The C variable is of type \fBdouble\fR.
+Any value written into the Tcl variable must have a proper real
+form acceptable to \fBTcl_GetDoubleFromObj\fR; attempts to write
+non-real values into \fIvarName\fR will be rejected with
+Tcl errors. Incomplete integer or real representations (like the
+empty string, '.', '+', '-' or the hex/octal/binary prefix) are
+accepted as if they are valid too.
+.TP
+\fBTCL_LINK_FLOAT\fR
+The C variable is of type \fBfloat\fR.
+Any value written into the Tcl variable must have a proper real
+form acceptable to \fBTcl_GetDoubleFromObj\fR and must be within the
+range acceptable for a \fBfloat\fR; attempts to
+write non-real values (or values outside the range) into
+\fIvarName\fR will be rejected with Tcl errors. Incomplete integer
+or real representations (like the empty string, '.', '+', '-' or
+the hex/octal/binary prefix) are accepted as if they are valid too.
+.TP
+\fBTCL_LINK_WIDE_INT\fR
+The C variable is of type \fBTcl_WideInt\fR (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 \fBTcl_GetWideIntFromObj\fR; attempts to write
+non-integer values into \fIvarName\fR will be rejected with
+Tcl errors. Incomplete integer representations (like the empty
+string, '+', '-' or the hex/octal/binary prefix) are accepted
+as if they are valid too.
+.TP
+\fBTCL_LINK_WIDE_UINT\fR
+The C variable is of type \fBTcl_WideUInt\fR (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 \fBTcl_GetWideIntFromObj\fR (it will be
+cast to unsigned);
+.\" FIXME! Use bignums instead.
+attempts to write non-integer values into \fIvarName\fR will be
+rejected with Tcl errors. Incomplete integer representations (like
+the empty string, '+', '-' or the hex/octal/binary prefix) are accepted
+as if they are valid too.
+.TP
+\fBTCL_LINK_BOOLEAN\fR
+The C variable is of type \fBint\fR.
+If its value is zero then it will read from Tcl as
+.QW 0 ;
+otherwise it will read from Tcl as
+.QW 1 .
+Whenever \fIvarName\fR 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 \fBTcl_GetBooleanFromObj\fR; attempts to write
+non-boolean values into \fIvarName\fR will be rejected with
+Tcl errors.
+.TP
+\fBTCL_LINK_STRING\fR
+The C variable is of type \fBchar *\fR.
+If its value is not NULL then it must be a pointer to a string
+allocated with \fBTcl_Alloc\fR or \fBckalloc\fR.
+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
+.QW NULL .
+.PP
+If the \fBTCL_LINK_READ_ONLY\fR flag is present in \fItype\fR 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.
+.PP
+\fBTcl_UnlinkVar\fR removes the link previously set up for the
+variable given by \fIvarName\fR. If there does not exist a link
+for \fIvarName\fR then the procedure has no effect.
+.PP
+\fBTcl_UpdateLinkedVar\fR 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.
+\fBTcl_UpdateLinkedVar\fR ensures that any traces on the Tcl
+variable are invoked.
+.PP
+Note that, as with any call to a Tcl interpreter, \fBTcl_UpdateLinkedVar\fR
+must be called from the same thread that created the interpreter. The safest
+mechanism is to ensure that the C variable is only ever updated from the same
+thread that created the interpreter (possibly in response to an event posted
+with \fBTcl_ThreadQueueEvent\fR), but when it is necessary to update the
+variable in a separate thread, it is advised that \fBTcl_AsyncMark\fR be used
+to indicate to the thread hosting the interpreter that it is ready to run
+\fBTcl_UpdateLinkedVar\fR.
+.SH "SEE ALSO"
+Tcl_TraceVar(3)
+.SH KEYWORDS
+boolean, integer, link, read-only, real, string, trace, variable
OSDN Git Service
