DOKK / manpages / debian 12 / tcl8.6-doc / Tcl_EvalObjEx.3tcl.en
Tcl_Eval(3tcl) Tcl Library Procedures Tcl_Eval(3tcl) 







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 value 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 values in the array pointed to by objv; this is also
      the number of words in the command.

  
Tcl_Obj **objv (in)

  
Points to an array of pointers to values; each value 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).

  
const 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 value 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 value 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 values 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 a value 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 value 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:



  

  
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 a value 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.

  

  
If this flag is set, the script is evaluated in the global namespace
      instead of the current namespace and its variable context consists of
      global variables only (it ignores any Tcl procedures that 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 than TCL_OK or
    TCL_ERROR.










execute, file, global, result, script, value







  

    8.1
    Tcl