- NAME
- Tcl_SubstObj — perform substitutions on Tcl values
- SYNOPSIS
- #include <tcl.h>
- Tcl_Obj *
- Tcl_SubstObj(interp, objPtr, flags)
- ARGUMENTS
- DESCRIPTION
- REFERENCE
COUNT MANAGEMENT
- SEE
ALSO
- KEYWORDS
Tcl_SubstObj — perform substitutions on Tcl values
#include <tcl.h>
Tcl_Obj *
Tcl_SubstObj(interp, objPtr, flags)
- 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.
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.
The objPtr argument to Tcl_SubstObj must not have a
reference count of zero. This function modifies the interpreter
result, both on success and on failure; the result of this function
on success is exactly the current interpreter result. Successful
results should have their reference count incremented if they are
to be retained.
subst
backslash
substitution, command
substitution, variable
substitution
Copyright © 2001 Donal K. Fellows