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>Calling User Functions</TITLE
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CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="calling-user-functions"
>Calling User Functions</A
></H1
><P
>&#13;   To call user functions from an internal function, you should use
   the <B
CLASS="function"
>call_user_function()</B
> function.
  </P
><P
>&#13;   <B
CLASS="function"
>call_user_function()</B
> returns SUCCESS on success,
   and FAILURE in case the function cannot be found.  You should check
   that return value!  If it returns SUCCESS, you are responsible for
   destroying the retval pval yourself (or return it as the return value
   of your function). If it returns FAILURE, the value of retval is
   undefined, and you mustn't touch it.
  </P
><P
>&#13;   All internal functions that call user functions
   <I
CLASS="emphasis"
>must</I
> be reentrant.  Among other things, this
   means they must not use globals or static variables.
  </P
><P
>&#13;   <B
CLASS="function"
>call_user_function()</B
> takes six arguments:
  </P
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="calling-user-functions.function-table"
>HashTable *function_table</A
></H2
><P
>&#13;    This is the hash table in which the function is to be looked up.
   </P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="calling-user-functions.object"
>pval *object</A
></H2
><P
>&#13;    This is a pointer to an object on which the function is invoked.
    This should be NULL if a global function is called.  If it's not
    NULL (i.e.  it points to an object), the function_table argument is
    ignored, and instead taken from the object's hash.  The object *may*
    be modified by the function that is invoked on it (that function
    will have access to it via $this).  If for some reason you don't
    want that to happen, send a copy of the object instead.
   </P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="calling-user-functions.function-name"
>pval *function_name</A
></H2
><P
>&#13;    The name of the function to call.  Must be a pval of type
    IS_STRING with function_name.str.val and function_name.str.len
    set to the appropriate values.  The function_name is modified by
    call_user_function() - it's converted to lowercase.  If you need to
    preserve the case, send a copy of the function name instead.
   </P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="calling-user-functions.retval"
>pval *retval</A
></H2
><P
>&#13;    A pointer to a pval structure, into which the return value of
    the invoked function is saved.  The structure must be previously
    allocated - <B
CLASS="function"
>call_user_function()</B
> does NOT allocate
    it by itself.
   </P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="calling-user-functions.param-count"
>int param_count</A
></H2
><P
>&#13;    The number of parameters being passed to the function.
   </P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="calling-user-functions.params"
>pval *params[]</A
></H2
><P
>&#13;    An array of pointers to values that will be passed as arguments to the
    function, the first argument being in offset 0, the second in offset
    1, etc.  The array is an array of pointers to pval's;  The pointers
    are sent as-is to the function, which means if the function modifies
    its arguments, the original values are changed (passing by reference).
    If you don't want that behavior, pass a copy instead.
   </P
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