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Diffstat (limited to 'doc/SetResult.3')
| -rw-r--r-- | doc/SetResult.3 | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/doc/SetResult.3 b/doc/SetResult.3 index 1622290..04a4b7f 100644 --- a/doc/SetResult.3 +++ b/doc/SetResult.3 @@ -239,6 +239,33 @@ typedef void \fBTcl_FreeProc\fR( .PP When \fIfreeProc\fR is called, its \fIblockPtr\fR will be set to the value of \fIresult\fR passed to \fBTcl_SetResult\fR. + +.SH "REFERENCE COUNT MANAGEMENT" +.PP +The interpreter result is one of the main places that owns references to +values, along with the bytecode execution stack, argument lists, variables, +and the list and dictionary collection values. +.PP +\fBTcl_SetObjResult\fR takes a value with an arbitrary reference count +\fI(specifically including zero)\fR and guarantees to increment the reference +count. If code wishes to continue using the value after setting it as the +result, it should add its own reference to it with \fBTcl_IncrRefCount\fR. +.PP +\fBTcl_GetObjResult\fR returns the current interpreter result value. This will +have a reference count of at least 1. If the caller wishes to keep the +interpreter result value, it should increment its reference count. +.PP +\fBTcl_GetStringResult\fR does not manipulate reference counts, but the string +it returns is owned by (and has a lifetime controlled by) the current +interpreter result value; it should be copied instead of being relied upon to +persist after the next Tcl API call, as most Tcl operations can modify the +interpreter result. +.PP +\fBTcl_SetResult\fR, \fBTcl_AppendResult\fR, \fBTcl_AppendResultVA\fR, +\fBTcl_AppendElement\fR, and \fBTcl_ResetResult\fR all modify the interpreter +result. They may cause the old interpreter result to have its reference count +decremented and a new interpreter result to be allocated. After they have been +called, the reference count of the interpreter result is guaranteed to be 1. .SH "SEE ALSO" Tcl_AddErrorInfo, Tcl_CreateObjCommand, Tcl_SetErrorCode, Tcl_Interp, Tcl_GetReturnOptions |