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diff --git a/tcl8.6/doc/LinkVar.3 b/tcl8.6/doc/LinkVar.3 new file mode 100644 index 0000000..c80d30d --- /dev/null +++ b/tcl8.6/doc/LinkVar.3 @@ -0,0 +1,231 @@ +'\" +'\" 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 |