diff options
Diffstat (limited to 'tcl/doc/StringObj.3')
| -rw-r--r-- | tcl/doc/StringObj.3 | 69 |
1 files changed, 46 insertions, 23 deletions
diff --git a/tcl/doc/StringObj.3 b/tcl/doc/StringObj.3 index 1d366b6135a..820b35a3e6e 100644 --- a/tcl/doc/StringObj.3 +++ b/tcl/doc/StringObj.3 @@ -10,33 +10,31 @@ .TH Tcl_StringObj 3 8.1 Tcl "Tcl Library Procedures" .BS .SH NAME -Tcl_NewStringObj, Tcl_NewUnicodeObj, Tcl_SetStringObj, Tcl_SetUnicodeObj, Tcl_GetStringFromObj, Tcl_GetString, Tcl_GetUnicode, Tcl_GetUniChar, Tcl_GetCharLength, Tcl_GetRange, Tcl_AppendToObj, Tcl_AppendUnicodeToObj, Tcl_AppendStringsToObj, Tcl_AppendStringsToObjVA, Tcl_AppendObjToObj, Tcl_SetObjLength, Tcl_ConcatObj \- manipulate Tcl objects as strings +Tcl_NewStringObj, Tcl_NewUnicodeObj, Tcl_SetStringObj, Tcl_SetUnicodeObj, Tcl_GetStringFromObj, Tcl_GetString, Tcl_GetUnicodeFromObj, Tcl_GetUnicode, Tcl_GetUniChar, Tcl_GetCharLength, Tcl_GetRange, Tcl_AppendToObj, Tcl_AppendUnicodeToObj, Tcl_AppendStringsToObj, Tcl_AppendStringsToObjVA, Tcl_AppendObjToObj, Tcl_SetObjLength, Tcl_ConcatObj, Tcl_AttemptSetObjLength \- manipulate Tcl objects as strings .SH SYNOPSIS .nf \fB#include <tcl.h>\fR .sp Tcl_Obj * \fBTcl_NewStringObj\fR(\fIbytes, length\fR) -.VS 8.1.2 .sp Tcl_Obj * \fBTcl_NewUnicodeObj\fR(\fIunicode, numChars\fR) -.VE .sp void \fBTcl_SetStringObj\fR(\fIobjPtr, bytes, length\fR) -.VS 8.1.2 .sp void \fBTcl_SetUnicodeObj\fR(\fIobjPtr, unicode, numChars\fR) -.VE .sp char * \fBTcl_GetStringFromObj\fR(\fIobjPtr, lengthPtr\fR) .sp char * \fBTcl_GetString\fR(\fIobjPtr\fR) -.VS 8.1.2 +.sp +Tcl_UniChar * +\fBTcl_GetUnicodeFromObj\fR(\fIobjPtr, lengthPtr\fR) .sp Tcl_UniChar * \fBTcl_GetUnicode\fR(\fIobjPtr\fR) @@ -49,15 +47,12 @@ int .sp Tcl_Obj * \fBTcl_GetRange\fR(\fIobjPtr, first, last\fR) -.VE .sp void \fBTcl_AppendToObj\fR(\fIobjPtr, bytes, length\fR) -.VS 8.1.2 .sp void \fBTcl_AppendUnicodeToObj\fR(\fIobjPtr, unicode, numChars\fR) -.VE .sp void \fBTcl_AppendObjToObj\fR(\fIobjPtr, appendObjPtr\fR) @@ -71,11 +66,14 @@ void void \fBTcl_SetObjLength\fR(\fIobjPtr, newLength\fR) .sp +int +\fBTcl_AttemptSetObjLength\fR(\fIobjPtr, newLength\fR) +.sp Tcl_Obj * \fBTcl_ConcatObj\fR(\fIobjc, objv\fR) .SH ARGUMENTS .AS Tcl_Interp *appendObjPtr in/out -.AP char *bytes in +.AP "CONST char" *bytes in Points to the first byte of an array of bytes used to set or append to a string object. This byte array may contain embedded null bytes @@ -84,12 +82,11 @@ unless \fIlength\fR is negative. The number of bytes to copy from \fIbytes\fR when initializing, setting, or appending to a string object. If negative, all bytes up to the first null are used. -.AP Tcl_UniChar *unicode in +.AP "CONST Tcl_UniChar" *unicode in Points to the first byte of an array of Unicode characters used to set or append to a string object. This byte array may contain embedded null characters unless \fInumChars\fR is negative. -.VS 8.1.2 .AP int numChars in The number of Unicode characters to copy from \fIunicode\fR when initializing, setting, or appending to a string object. @@ -102,7 +99,6 @@ returned as a new object. .AP int last in The index of the last Unicode character in the Unicode range to be returned as a new object. -.VE .AP Tcl_Obj *objPtr in/out Points to an object to manipulate. .AP Tcl_Obj *appendObjPtr in @@ -110,7 +106,7 @@ The object to append to \fIobjPtr\fR in \fBTcl_AppendObjToObj\fR. .AP int *lengthPtr out If non-NULL, the location where \fBTcl_GetStringFromObj\fR will store the the length of an object's string representation. -.AP char *string in +.AP "CONST char" *string in Null-terminated string value to append to \fIobjPtr\fR. .AP va_list argList in An argument list which must have been initialised using @@ -132,12 +128,13 @@ of the object to store additional information to make the string manipulations more efficient. In particular, they make a series of append operations efficient by allocating extra storage space for the string so that it doesn't have to be copied for each append. -.VS 8.1.2 Also, indexing and length computations are optimized because the Unicode string representation is calculated and cached as needed. -.VE +When using the \fBTcl_Append*\fR family of functions where the +interpreter's result is the object being appended to, it is important +to call Tcl_ResetResult first to ensure you are not unintentionally +appending to existing data in the result object. .PP -.VS 8.1.2 \fBTcl_NewStringObj\fR and \fBTcl_SetStringObj\fR create a new object or modify an existing object to hold a copy of the string given by \fIbytes\fR and \fIlength\fR. \fBTcl_NewUnicodeObj\fR and @@ -149,7 +146,6 @@ All four procedures set the object to hold a copy of the specified string. \fBTcl_SetStringObj\fR and \fBTcl_SetUnicodeObj\fR free any old string representation as well as any old internal representation of the object. -.VE .PP \fBTcl_GetStringFromObj\fR and \fBTcl_GetString\fR return an object's string representation. This is given by the returned byte pointer and @@ -158,13 +154,31 @@ string representation. This is given by the returned byte pointer and representation is invalid (its byte pointer is NULL), the string representation is regenerated from the object's internal representation. The storage referenced by the returned byte pointer -is owned by the object manager and should not be modified by the -caller. The procedure \fBTcl_GetString\fR is used in the common case +is owned by the object manager. It is passed back as a writable +pointer so that extension author creating their own \fBTcl_ObjType\fR +will be able to modify the string representation within the +\fBTcl_UpdateStringProc\fR of their \fBTcl_ObjType\fR. Except for that +limited purpose, the pointer returned by \fBTcl_GetStringFromObj\fR +or \fBTcl_GetString\fR should be treated as read-only. It is +recommended that this pointer be assigned to a (CONST char *) variable. +Even in the limited situations where writing to this pointer is +acceptable, one should take care to respect the copy-on-write +semantics required by \fBTcl_Obj\fR's, with appropriate calls +to \fBTcl_IsShared\fR and \fBTcl_DuplicateObj\fR prior to any +in-place modification of the string representation. +The procedure \fBTcl_GetString\fR is used in the common case where the caller does not need the length of the string representation. .PP -.VS 8.1.2 -\fBTcl_GetUnicode\fR returns an object's value as a Unicode string. +\fBTcl_GetUnicodeFromObj\fR and \fBTcl_GetUnicode\fR return an object's +value as a Unicode string. This is given by the returned pointer and +(for \fBTcl_GetUnicodeFromObj\fR) length, which is stored in +\fIlengthPtr\fR if it is non-NULL. The storage referenced by the returned +byte pointer is owned by the object manager and should not be modified by +the caller. The procedure \fBTcl_GetUnicode\fR is used in the common case +where the caller does not need the length of the unicode string +representation. +.PP \fBTcl_GetUniChar\fR returns the \fIindex\fR'th character in the object's Unicode representation. .PP @@ -200,7 +214,6 @@ object's string value). appends the string or Unicode value (whichever exists and is best suited to be appended to \fIobjPtr\fR) of \fIappendObjPtr\fR to \fIobjPtr\fR. -.VE .PP \fBTcl_AppendStringsToObj\fR is similar to \fBTcl_AppendToObj\fR except that it can be passed more than one value to append and @@ -227,6 +240,16 @@ enlarged in a subsequent call to \fBTcl_SetObjLength\fR without reallocating storage. In all cases \fBTcl_SetObjLength\fR leaves a null character at \fIobjPtr->bytes[newLength]\fR. .PP +\fBTcl_AttemptSetObjLength\fR is identical in function to +\fBTcl_SetObjLength\fR except that if sufficient memory to satisfy the +request cannot be allocated, it does not cause the Tcl interpreter to +\fBpanic\fR. Thus, if \fInewLength\fR is greater than the space +allocated for the object's string, and there is not enough memory +available to satisfy the request, \fBTcl_AttemptSetObjLength\fR will take +no action and return 0 to indicate failure. If there is enough memory +to satisfy the request, \fBTcl_AttemptSetObjLength\fR behaves just like +\fBTcl_SetObjLength\fR and returns 1 to indicate success. +.PP The \fBTcl_ConcatObj\fR function returns a new string object whose value is the space-separated concatenation of the string representations of all of the objects in the \fIobjv\fR |