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<H2><A NAME="SLclass_set_push_function"></A> <A NAME="s44">44. <B>SLclass_set_push_function</B></A></H2>
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<DT><B> Synopsis </B><DD><P>Set the push callback for a new data type
<DT><B> Usage </B><DD><P><CODE>int SLclass_set_push_function (cl, push_fun)</CODE>
<BLOCKQUOTE><CODE>
<PRE>
SLang_Class_Type *cl
int (*push_fun) (unsigned char, VOID_STAR);
</PRE>
</CODE></BLOCKQUOTE>
<DT><B> Description </B><DD><P><CODE>SLclass_set_push_function</CODE> is used to set the push callback
for a new data type specified by <CODE>cl</CODE>, which must have been
previously obtained via <CODE>SLclass_allocate_class</CODE>.
<P>The parameter <CODE>push_fun</CODE> is a pointer to the push callback. It
is required to take two arguments: an unsigned character
representing the data type, and the address of the object to be
pushed. It must return zero upon success, or <CODE>-1</CODE> upon failure.
<P><CODE>SLclass_set_push_function</CODE> returns zero upon success, or <CODE>-1</CODE>
upon failure.
<DT><B> Example </B><DD><P>The push callback for <CODE>SLANG_COMPLEX_TYPE</CODE> looks like:
<BLOCKQUOTE><CODE>
<PRE>
static int complex_push (unsigned char type, VOID_STAR ptr)
{
double *z = *(double **) ptr;
return SLang_push_complex (z[0], z[1]);
}
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<DT><B> See Also </B><DD><P><CODE>SLclass_allocate_class, SLclass_register_class</CODE>
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