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ActiveTcl User Guide |
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- NAME
- Tcl_EvalObjEx, Tcl_EvalFile, Tcl_EvalObjv, Tcl_Eval,
Tcl_EvalEx, Tcl_GlobalEval, Tcl_GlobalEvalObj, Tcl_VarEval,
Tcl_VarEvalVA - execute Tcl scripts
- SYNOPSIS
- ARGUMENTS
- DESCRIPTION
- FLAG BITS
- TCL_EVAL_DIRECT
- TCL_EVAL_GLOBAL
- MISCELLANEOUS
DETAILS
- KEYWORDS
Tcl_EvalObjEx, Tcl_EvalFile, Tcl_EvalObjv, Tcl_Eval, Tcl_EvalEx,
Tcl_GlobalEval, Tcl_GlobalEvalObj, Tcl_VarEval, Tcl_VarEvalVA -
execute Tcl scripts
#include <tcl.h>
int
Tcl_EvalObjEx(interp, objPtr, flags)
int
Tcl_EvalFile(interp, fileName)
int
Tcl_EvalObjv(interp, objc, objv, flags)
int
Tcl_Eval(interp, script)
int
Tcl_EvalEx(interp, script, numBytes, flags)
int
Tcl_GlobalEval(interp, script)
int
Tcl_GlobalEvalObj(interp, objPtr)
int
Tcl_VarEval(interp, part, part, ... (char *)
NULL)
int
Tcl_VarEvalVA(interp, argList)
- Tcl_Interp *interp
(in)
- Interpreter in which to execute the script. The interpreter's
result is modified to hold the result or error message from the
script.
- Tcl_Obj *objPtr (in)
- A Tcl object containing the script to execute.
- int flags (in)
- ORed combination of flag bits that specify additional options.
TCL_EVAL_GLOBAL and TCL_EVAL_DIRECT are currently
supported.
- const char *fileName (in)
- Name of a file containing a Tcl script.
- int objc (in)
- The number of objects in the array pointed to by objPtr;
this is also the number of words in the command.
- Tcl_Obj **objv (in)
- Points to an array of pointers to objects; each object holds
the value of a single word in the command to execute.
- int numBytes (in)
- The number of bytes in script, not including any null
terminating character. If -1, then all characters up to the first
null byte are used.
- const char *script (in)
- Points to first byte of script to execute (null-terminated and
UTF-8).
- char *part (in)
- String forming part of a Tcl script.
- va_list argList (in)
- An argument list which must have been initialized using
va_start, and cleared using va_end.
The procedures described here are invoked to execute Tcl scripts in
various forms. Tcl_EvalObjEx is the core procedure and is
used by many of the others. It executes the commands in the script
stored in objPtr until either an error occurs or the end of
the script is reached. If this is the first time objPtr has
been executed, its commands are compiled into bytecode instructions
which are then executed. The bytecodes are saved in objPtr
so that the compilation step can be skipped if the object is
evaluated again in the future.
The return value from Tcl_EvalObjEx (and all the other
procedures described here) is a Tcl completion code with one of the
values TCL_OK, TCL_ERROR, TCL_RETURN,
TCL_BREAK, or TCL_CONTINUE, or possibly some other
integer value originating in an extension. In addition, a result
value or error message is left in interp's result; it can be
retrieved using Tcl_GetObjResult.
Tcl_EvalFile reads the file given by fileName and
evaluates its contents as a Tcl script. It returns the same
information as Tcl_EvalObjEx. If the file could not be read
then a Tcl error is returned to describe why the file could not be
read. The eofchar for files is “\32” (^Z) for all
platforms. If you require a “^Z” in code for string
comparison, you can use “\032” or “\u001a”,
which will be safely substituted by the Tcl interpreter into
“^Z”.
Tcl_EvalObjv executes a single pre-parsed command instead
of a script. The objc and objv arguments contain the
values of the words for the Tcl command, one word in each object in
objv. Tcl_EvalObjv evaluates the command and returns
a completion code and result just like Tcl_EvalObjEx. The
caller of Tcl_EvalObjv has to manage the reference count of
the elements of objv, insuring that the objects are valid
until Tcl_EvalObjv returns.
Tcl_Eval is similar to Tcl_EvalObjEx except that
the script to be executed is supplied as a string instead of an
object and no compilation occurs. The string should be a proper
UTF-8 string as converted by Tcl_ExternalToUtfDString or Tcl_ExternalToUtf when it is
known to possibly contain upper ASCII characters whose possible
combinations might be a UTF-8 special code. The string is parsed
and executed directly (using Tcl_EvalObjv) instead of
compiling it and executing the bytecodes. In situations where it is
known that the script will never be executed again, Tcl_Eval
may be faster than Tcl_EvalObjEx. Tcl_Eval returns a
completion code and result just like Tcl_EvalObjEx. Note:
for backward compatibility with versions before Tcl 8.0,
Tcl_Eval copies the object result in interp to
interp->result (use is deprecated) where it can be
accessed directly. This makes Tcl_Eval somewhat slower than
Tcl_EvalEx, which does not do the copy.
Tcl_EvalEx is an extended version of Tcl_Eval that
takes additional arguments numBytes and flags. For
the efficiency reason given above, Tcl_EvalEx is generally
preferred over Tcl_Eval.
Tcl_GlobalEval and Tcl_GlobalEvalObj are older
procedures that are now deprecated. They are similar to
Tcl_EvalEx and Tcl_EvalObjEx except that the script
is evaluated in the global namespace and its variable context
consists of global variables only (it ignores any Tcl procedures
that are active). These functions are equivalent to using the
TCL_EVAL_GLOBAL flag (see below).
Tcl_VarEval takes any number of string arguments of any
length, concatenates them into a single string, then calls
Tcl_Eval to execute that string as a Tcl command. It returns
the result of the command and also modifies
interp->result in the same way as Tcl_Eval. The
last argument to Tcl_VarEval must be NULL to indicate the
end of arguments. Tcl_VarEval is now deprecated.
Tcl_VarEvalVA is the same as Tcl_VarEval except
that instead of taking a variable number of arguments it takes an
argument list. Like Tcl_VarEval, Tcl_VarEvalVA is
deprecated.
Any ORed combination of the following values may be used for the
flags argument to procedures such as Tcl_EvalObjEx:
- TCL_EVAL_DIRECT
- This flag is only used by Tcl_EvalObjEx; it is ignored
by other procedures. If this flag bit is set, the script is not
compiled to bytecodes; instead it is executed directly as is done
by Tcl_EvalEx. The TCL_EVAL_DIRECT flag is useful in
situations where the contents of an object are going to change
immediately, so the bytecodes will not be reused in a future
execution. In this case, it is faster to execute the script
directly.
- TCL_EVAL_GLOBAL
- If this flag is set, the script is processed at global level.
This means that it is evaluated in the global namespace and its
variable context consists of global variables only (it ignores any
Tcl procedures at are active).
During the processing of a Tcl command it is legal to make nested
calls to evaluate other commands (this is how procedures and some
control structures are implemented). If a code other than
TCL_OK is returned from a nested Tcl_EvalObjEx
invocation, then the caller should normally return immediately,
passing that same return code back to its caller, and so on until
the top-level application is reached. A few commands, like for, will check for certain return
codes, like TCL_BREAK and TCL_CONTINUE, and process
them specially without returning.
Tcl_EvalObjEx keeps track of how many nested
Tcl_EvalObjEx invocations are in progress for interp.
If a code of TCL_RETURN, TCL_BREAK, or
TCL_CONTINUE is about to be returned from the topmost
Tcl_EvalObjEx invocation for interp, it converts the
return code to TCL_ERROR and sets interp's result to
an error message indicating that the return, break, or continue command was invoked in an
inappropriate place. This means that top-level applications should
never see a return code from Tcl_EvalObjEx other then
TCL_OK or TCL_ERROR.
execute, file, global, object, result, script
Copyright © 1995-1997 Roger E. Critchlow Jr.
Copyright © 1989-1993 The Regents of the University of
California. Copyright © 1994-1997 Sun Microsystems, Inc.
Copyright © 2000 Scriptics Corporation.