Страницы справочника OS X

Эта страница руководства является частью версии 5.0 Инструментов XCode

Читать страницы руководства

Tcl_LinkVar(3)                             Tcl Library Procedures                             Tcl_LinkVar(3)



____________________________________________________________________________________________________________

NAME
       Tcl_LinkVar, Tcl_UnlinkVar, Tcl_UpdateLinkedVar - link Tcl variable to C variable

SYNOPSIS
       #include <tcl.h>

       int
       Tcl_LinkVar(interp, varName, addr, type)

       Tcl_UnlinkVar(interp, varName)

       Tcl_UpdateLinkedVar(interp, varName)

ARGUMENTS
       Tcl_Interp *interp (in)           Interpreter  that  contains  varName.   Also used by Tcl_LinkVar to
                                         return error messages.

       const char *varName (in)          Name of global variable.

       char *addr (in)                   Address of C variable that is to be linked to varName.

       int type (in)                     Type of C variable.  Must be one  of  TCL_LINK_INT,  TCL_LINK_UINT, |
                                         TCL_LINK_CHAR,   TCL_LINK_UCHAR,  TCL_LINK_SHORT,  TCL_LINK_USHORT, |
                                         TCL_LINK_LONG,          TCL_LINK_ULONG,          TCL_LINK_WIDE_INT, |
                                         TCL_LINK_WIDE_UINT,         TCL_LINK_FLOAT,        TCL_LINK_DOUBLE,
                                         TCL_LINK_BOOLEAN,  or  TCL_LINK_STRING,   optionally   OR'ed   with
                                         TCL_LINK_READ_ONLY to make Tcl variable read-only.
____________________________________________________________________________________________________________


DESCRIPTION
       Tcl_LinkVar  uses  variable traces to keep the Tcl variable named by varName in sync with the C vari-able variable
       able at the address given by addr.  Whenever the Tcl variable is read the value  of  the  C  variable
       will be returned, and whenever the Tcl variable is written the C variable will be updated to have the
       same value.  Tcl_LinkVar normally returns TCL_OK;  if an error occurs while setting up the link (e.g.
       because  varName  is  the name of array) then TCL_ERROR is returned and the interpreter's result con-tains contains
       tains an error message.

       The type argument specifies the type of the C variable, and must have one of  the  following  values,
       optionally OR'ed with TCL_LINK_READ_ONLY:

       TCL_LINK_INT
              The  C  variable  is  of type int.  Any value written into the Tcl variable must have a proper
              integer form acceptable to Tcl_GetIntFromObj;  attempts to write non-integer values into  var-Name varName
              Name will be rejected with Tcl errors.                                                         |

       TCL_LINK_UINT                                                                                         ||
              The C variable is of type unsigned int.  Any value written into the Tcl variable must  have  a |
              proper unsigned integer form acceptable to Tcl_GetWideIntFromObj and in the platform's defined |
              range for the unsigned int type; attempts to write non-integer values (or values  outside  the |
              range) into varName will be rejected with Tcl errors.                                          |

       TCL_LINK_CHAR                                                                                         ||
              The C variable is of type char.  Any value written into the Tcl variable must  have  a  proper |
              integer  form  acceptable  to  Tcl_GetIntFromObj  and  be  in  the range of the char datatype; |
              attempts to write non-integer or out-of-range values into varName will be  rejected  with  Tcl |
              errors.                                                                                        |

       TCL_LINK_UCHAR                                                                                        ||
              The C variable is of type unsigned char.  Any value written into the Tcl variable must have  a |
              proper  unsigned  integer  form  acceptable to Tcl_GetIntFromObj and in the platform's defined |
              range for the unsigned char type; attempts to write non-integer values (or values outside  the |
              range) into varName will be rejected with Tcl errors.                                          |

       TCL_LINK_SHORT                                                                                        ||
              The C variable is of type short.  Any value written into the Tcl variable must have  a  proper |
              integer  form  acceptable  to  Tcl_GetIntFromObj  and  be  in the range of the short datatype; |
              attempts to write non-integer or out-of-range values into varName will be  rejected  with  Tcl |
              errors.                                                                                        |

       TCL_LINK_USHORT                                                                                       ||
              The C variable is of type unsigned short.  Any value written into the Tcl variable must have a |
              proper  unsigned  integer  form  acceptable to Tcl_GetIntFromObj and in the platform's defined |
              range for the unsigned short type; attempts to write non-integer values (or values outside the |
              range) into varName will be rejected with Tcl errors.                                          |

       TCL_LINK_LONG                                                                                         ||
              The C variable is of type long.  Any value written into the Tcl variable must  have  a  proper |
              integer  form  acceptable to Tcl_GetLongFromObj; attempts to write non-integer or out-of-range |
              values into varName will be rejected with Tcl errors.                                          |

       TCL_LINK_ULONG                                                                                        ||
              The  C variable is of type unsigned long.  Any value written into the Tcl variable must have a |
              proper unsigned integer form acceptable to Tcl_GetWideIntFromObj and in the platform's defined |
              range  for the unsigned long type; attempts to write non-integer values (or values outside the |
              range) into varName will be rejected with Tcl errors.

       TCL_LINK_DOUBLE
              The C variable is of type double.  Any value written into the Tcl variable must have a  proper
              real  form acceptable to Tcl_GetDoubleFromObj;  attempts to write non-real values into varName
              will be rejected with Tcl errors.                                                              |

       TCL_LINK_FLOAT                                                                                        ||
              The  C  variable is of type float.  Any value written into the Tcl variable must have a proper |
              real form acceptable to Tcl_GetDoubleFromObj and must be within the  range  acceptable  for  a |
              float;  attempts  to  write non-real values (or values outside the range) into varName will be |
              rejected with Tcl errors.

       TCL_LINK_WIDE_INT
              The C variable is of type Tcl_WideInt (which is an integer type at least 64-bits wide  on  all
              platforms  that  can  support it.)  Any value written into the Tcl variable must have a proper
              integer form acceptable to Tcl_GetWideIntFromObj;  attempts to write non-integer  values  into
              varName will be rejected with Tcl errors.                                                      |

       TCL_LINK_WIDE_UINT                                                                                    ||
              The C variable is of type Tcl_WideUInt (which is an unsigned integer  type  at  least  64-bits |
              wide on all platforms that can support it.)  Any value written into the Tcl variable must have |
              a proper unsigned integer form  acceptable  to  Tcl_GetWideIntFromObj  (it  will  be  cast  to |
              unsigned); attempts to write non-integer values into varName will be rejected with Tcl errors.

       TCL_LINK_BOOLEAN
              The C variable is of type int.  If its value is zero then it will read from Tcl as "0"; other-wise otherwise
              wise  it  will read from Tcl as "1".  Whenever varName is modified, the C variable will be set
              to a 0 or 1 value.  Any value written into the Tcl variable must have a  proper  boolean  form
              acceptable  to  Tcl_GetBooleanFromObj;  attempts to write non-boolean values into varName will
              be rejected with Tcl errors.

       TCL_LINK_STRING
              The C variable is of type char *.  If its value is not NULL then it must be  a  pointer  to  a
              string allocated with Tcl_Alloc or ckalloc.  Whenever the Tcl variable is modified the current
              C string will be freed and new memory will be allocated to hold a copy of the  variable's  new
              value.  If the C variable contains a NULL pointer then the Tcl variable will read as "NULL".

       If  the  TCL_LINK_READ_ONLY  flag is present in type then the variable will be read-only from Tcl, so
       that its value can only be changed by modifying the C variable.  Attempts to write the variable  from
       Tcl will be rejected with errors.

       Tcl_UnlinkVar  removes  the  link previously set up for the variable given by varName.  If there does
       not exist a link for varName then the procedure has no effect.

       Tcl_UpdateLinkedVar may be invoked after the C variable has changed to force the Tcl variable  to  be
       updated  immediately.   In many cases this procedure is not needed, since any attempt to read the Tcl
       variable will return the latest value of the C variable.  However, if a trace has been set on the Tcl
       variable  (such  as a Tk widget that wishes to display the value of the variable), the trace will not
       trigger when the C variable has changed.  Tcl_UpdateLinkedVar ensures that  any  traces  on  the  Tcl
       variable are invoked.


KEYWORDS
       boolean, integer, link, read-only, real, string, traces, variable



Tcl                                                  7.5                                      Tcl_LinkVar(3)