1Tcl_SubstObj(3) Tcl Library Procedures Tcl_SubstObj(3)
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8 Tcl_SubstObj - perform substitutions on Tcl objects
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11 #include <tcl.h>
12 Tcl_Obj *
14 Tcl_SubstObj(interp, objPtr, flags)
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17 Tcl_Interp *interp (in) Interpreter in which to execute Tcl
18 scripts and lookup variables. If
19 an error occurs, the interpreter's
20 result is modified to hold an error
21 message.
22 Tcl_Obj *objPtr (in) A Tcl object containing the string
24 to perform substitutions on.
25 int flags (in) ORed combination of flag bits that
27 specify which substitutions to per‐
28 form. The flags TCL_SUBST_COM‐
29 MANDS, TCL_SUBST_VARIABLES and
30 TCL_SUBST_BACKSLASHES are currently
31 supported, and TCL_SUBST_ALL is
32 provided as a convenience for the
33 common case where all substitutions
34 are desired.
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39 The Tcl_SubstObj function is used to perform substitutions on strings
40 in the fashion of the subst command. It gets the value of the string
41 contained in objPtr and scans it, copying characters and performing the
42 chosen substitutions as it goes to an output object which is returned
43 as the result of the function. In the event of an error occurring dur‐
44 ing the execution of a command or variable substitution, the function
45 returns NULL and an error message is left in interp's result.
46 Three kinds of substitutions are supported. When the TCL_SUBST_BACK‐
48 SLASHES bit is set in flags, sequences that look like backslash substi‐
49 tutions for Tcl commands are replaced by their corresponding character.
50 When the TCL_SUBST_VARIABLES bit is set in flags, sequences that look
52 like variable substitutions for Tcl commands are replaced by the con‐
53 tents of the named variable.
54 When th TCL_SUBST_COMMANDS bit is set in flags, sequences that look
56 like command substitutions for Tcl commands are replaced by the result
57 of evaluating that script. Where an uncaught continue exception occurs
58 during the evaluation of a command substitution, an empty string is
59 substituted for the command. Where an uncaught break exception occurs
60 during the evaluation of a command substitution, the result of the
61 whole substitution on objPtr will be truncated at the point immediately
62 before the start of the command substitution, and no characters will be
63 added to the result or substitutions performed after that point.
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67 subst(n)
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71 backslash substitution, command substitution, variable substitution
72Tcl 8.4 Tcl_SubstObj(3)