NAME

       Tcl_SubstObj - perform substitutions on Tcl values

SYNOPSIS

       #include <tcl.h>

       Tcl_Obj *
       Tcl_SubstObj(interp, objPtr, flags)

ARGUMENTS

       Tcl_Interp *interp (in)            Interpreter  in which to execute Tcl scripts and lookup variables.  If
                                          an error occurs, the interpreter's result is modified to hold an error
                                          message.

       Tcl_Obj *objPtr (in)               A Tcl value containing the string to perform substitutions on.

       int flags (in)                     OR'ed combination of flag bits that  specify  which  substitutions  to
                                          perform.    The   flags  TCL_SUBST_COMMANDS,  TCL_SUBST_VARIABLES  and
                                          TCL_SUBST_BACKSLASHES are currently supported,  and  TCL_SUBST_ALL  is
                                          provided  as a convenience for the common case where all substitutions
                                          are desired.
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DESCRIPTION

       The Tcl_SubstObj function is used to perform substitutions  on  strings  in  the  fashion  of  the  subst
       command.   It  gets  the  value  of  the  string contained in objPtr and scans it, copying characters and
       performing the chosen substitutions as it goes to an output value which is returned as the result of  the
       function.  In the event of an error occurring during the execution of a command or variable substitution,
       the function returns NULL and an error message is left in interp's result.

       Three  kinds  of  substitutions  are  supported.   When  the  TCL_SUBST_BACKSLASHES  bit is set in flags,
       sequences that look like backslash substitutions for Tcl commands are  replaced  by  their  corresponding
       character.

       When the TCL_SUBST_VARIABLES bit is set in flags, sequences that look like variable substitutions for Tcl
       commands are replaced by the contents of the named variable.

       When  the  TCL_SUBST_COMMANDS bit is set in flags, sequences that look like command substitutions for Tcl
       commands are replaced by the result of evaluating that script.  Where an  uncaught  “continue  exception”
       occurs  during  the evaluation of a command substitution, an empty string is substituted for the command.
       Where an uncaught “break exception” occurs during the evaluation of a command substitution, the result of
       the whole substitution on objPtr will be truncated at the point  immediately  before  the  start  of  the
       command substitution, and no characters will be added to the result or substitutions performed after that
       point.

SEE ALSO

       subst(3tcl)

KEYWORDS

       backslash substitution, command substitution, variable substitution

Tcl                                                    8.4                                    Tcl_SubstObj(3tcl)